WO2007054739A1 - Tetrahydroindole derivatives for treatment of alzheimer's disease - Google Patents

Tetrahydroindole derivatives for treatment of alzheimer's disease Download PDF

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WO2007054739A1
WO2007054739A1 PCT/GB2006/050368 GB2006050368W WO2007054739A1 WO 2007054739 A1 WO2007054739 A1 WO 2007054739A1 GB 2006050368 W GB2006050368 W GB 2006050368W WO 2007054739 A1 WO2007054739 A1 WO 2007054739A1
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compound according
phenyl
mixture
groups
mmol
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PCT/GB2006/050368
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French (fr)
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Frank Burkamp
Graham David Checksfield
Stephen Robert Fletcher
Stephen John Lewis
Edward Giles Mciver
Paul Joseph Oakley
Martin Richard Teall
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Merck Sharp & Dohme Limited
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Priority to AU2006313537A priority Critical patent/AU2006313537A1/en
Priority to AT06808732T priority patent/ATE519740T1/en
Priority to EP06808732A priority patent/EP1948603B1/en
Priority to CA002628934A priority patent/CA2628934A1/en
Priority to US12/084,814 priority patent/US8203004B2/en
Priority to JP2008539507A priority patent/JP2009515864A/en
Publication of WO2007054739A1 publication Critical patent/WO2007054739A1/en

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    • C07D209/00Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom
    • C07D209/02Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom condensed with one carbocyclic ring
    • C07D209/04Indoles; Hydrogenated indoles
    • C07D209/30Indoles; Hydrogenated indoles with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, directly attached to carbon atoms of the hetero ring
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61PSPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
    • A61P25/00Drugs for disorders of the nervous system
    • A61P25/28Drugs for disorders of the nervous system for treating neurodegenerative disorders of the central nervous system, e.g. nootropic agents, cognition enhancers, drugs for treating Alzheimer's disease or other forms of dementia
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61PSPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
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    • C07DHETEROCYCLIC COMPOUNDS
    • C07D209/00Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom
    • C07D209/02Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom condensed with one carbocyclic ring
    • C07D209/04Indoles; Hydrogenated indoles
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    • C07DHETEROCYCLIC COMPOUNDS
    • C07D209/00Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom
    • C07D209/02Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom condensed with one carbocyclic ring
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    • C07DHETEROCYCLIC COMPOUNDS
    • C07D209/00Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom
    • C07D209/02Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom condensed with one carbocyclic ring
    • C07D209/04Indoles; Hydrogenated indoles
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    • C07ORGANIC CHEMISTRY
    • C07DHETEROCYCLIC COMPOUNDS
    • C07D209/00Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom
    • C07D209/02Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom condensed with one carbocyclic ring
    • C07D209/04Indoles; Hydrogenated indoles
    • C07D209/30Indoles; Hydrogenated indoles with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, directly attached to carbon atoms of the hetero ring
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    • C07D209/00Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom
    • C07D209/56Ring systems containing three or more rings
    • C07D209/80[b, c]- or [b, d]-condensed
    • C07D209/82Carbazoles; Hydrogenated carbazoles
    • C07D209/86Carbazoles; Hydrogenated carbazoles with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached to carbon atoms of the ring system
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    • C07D401/02Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings
    • C07D401/04Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings directly linked by a ring-member-to-ring-member bond
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    • C07D405/02Heterocyclic compounds containing both one or more hetero rings having oxygen atoms as the only ring hetero atoms, and one or more rings having nitrogen as the only ring hetero atom containing two hetero rings
    • C07D405/04Heterocyclic compounds containing both one or more hetero rings having oxygen atoms as the only ring hetero atoms, and one or more rings having nitrogen as the only ring hetero atom containing two hetero rings directly linked by a ring-member-to-ring-member bond
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    • C07D409/04Heterocyclic compounds containing two or more hetero rings, at least one ring having sulfur atoms as the only ring hetero atoms containing two hetero rings directly linked by a ring-member-to-ring-member bond

Definitions

  • This invention relates to methods and materials for use in therapeutic treatment of the human body.
  • it provides materials for treating diseases associated with the deposition of ⁇ -amyloid peptide in the brain, such as Alzheimer's disease, or of preventing or delaying the onset of dementia associated with such diseases.
  • AD Alzheimer's disease
  • DSM-IV American Psychiatric Association
  • a ⁇ fibrillar aggregates of ⁇ -amyloid peptide
  • a ⁇ is formed from amyloid precursor protein (APP) via separate intracellular proteolytic events involving the enzymes ⁇ -secretase and ⁇ -secretase.
  • APP amyloid precursor protein
  • a ⁇ of varying chain length e.g. A ⁇ (l-38), A ⁇ (l-40) and A ⁇ (l-42).
  • N-terminal truncations such as A ⁇ (4-42) are also found in the brain, possibly as a result of variability in the site of proteolysis mediated by ⁇ -secretase.
  • expressions such as "A ⁇ (l-40)” and “A ⁇ (l-42)" as used herein are inclusive of such N- terminal truncated variants.
  • a ⁇ After secretion into the extracellular medium, A ⁇ forms initially-soluble aggregates which are widely believed to be the key neurotoxic agents in AD (see Gong et al, PNAS, 100 (2003), 10417-22), and which ultimately result in the insoluble deposits and dense neuritic plaques which are the pathological characteristics of AD.
  • a ⁇ dementing conditions associated with deposition of A ⁇ in the brain include cerebral amyloid angiopathy, hereditary cerebral haemorrhage with amyloidosis, Dutch-type (HCHWA-D), multi-infarct dementia, dementia pugilistica and Down syndrome.
  • Various interventions in the plaque-forming process have been proposed as therapeutic treatments for AD (see, for example, Hardy and Selkoe, Science, 297 (2002), 353-6).
  • One such method of treatment that has been proposed is that of blocking or attenuating the production of A ⁇ for example by inhibition of ⁇ - or ⁇ -secretase.
  • GSK-3 glycogen synthase kinase-3
  • Other proposed methods of treatment include administering a compound which blocks the aggregation of A ⁇ , and administering an antibody which selectively binds to A ⁇ .
  • NSAIDs non-steroidal antiinflammatory drugs
  • analogues see WO 01/78721 and US 2002/0128319 and Weggen et al Nature, 414 (2001) 212-16; Morihara et al, J. Neurochem., 83 (2002), 1009-12; and Takahashi et al, J. Biol. Chem., 278 (2003), 18644-70).
  • WO 2005/054193 and WO 2005/013985 disclose further classes of compounds which selectively attenuate A ⁇ (l-42).
  • V represents a bond, CH 2 or CH 2 CH 2 ;
  • X represents CR la or N
  • Y represents CO 2 H or tetrazole
  • Ar represents phenyl which optionally bears up to 3 substituents independently selected from hydrocarbon groups of up to 6 carbon atoms and (CH 2 ) m -Z where m is 0, 1 or 2 and Z represents halogen, N 3 , CN, CF 3 , OCF 3 or OR 4 ;
  • R 1 represents halogen, CN, R 4 CO, CF 3 , CH 2 N(R 4 ) 2 , a branched Ci.i O alkyl group, a Ci.i O alkenyl group, or a non-aromatic cyclic group of up to 7 ring atoms of which up to 2 may be selected from N, O and S; or when X is CR la , R 1 and R la may complete a fused cycloalkene ring of 5, 6 or 7 members which is optionally substituted with up to 2 groups;
  • R la represents H or or combines with R 1 as defined above; with the proviso that when X is CH, R 1 is not t-butyl; each R 2 is independently H or Ci ⁇ alkyl; R 3 is H, hydrocarbon containing up to 10 carbon atoms, or heterocyclylCi.
  • R 4 represents H or a hydrocarbon group of up to 7 carbon atoms, optionally substituted with halogen, CN, CF 3 , OH, or two R 4 groups attached to a nitrogen atom may complete ring selected from pyrrolidine, piperidine, morpholine, thiomorpholine, tetrahydropyridine and piperazine, any of which rings optionally bearing a substituent selected from CF 3 , and phenyl;
  • R 5 represents R 4 that is other than H; p is 0, 1 or 2; and
  • R 6 represents Ci -6 alkyl, C 2-6 alkenyl or phenyl, benzyl or heteroaryl, said phenyl, benzyl or heteroaryl optionally bearing up to 3 substituents selected from halogen, CN, CF 3 , OCF 3 , OR 4 , CO 2 R 4 , or a pharmaceutically acceptable salt or hydrate thereof.
  • substituents selected from halogen, CN, CF 3 , OCF 3 , OR 4 , CO 2 R 4 , or a pharmaceutically acceptable salt or hydrate thereof.
  • hydrocarbon group refers to groups consisting solely of carbon and hydrogen atoms. Such groups may comprise linear, branched or cyclic structures, singly or in any combination consistent with the indicated maximum number of carbon atoms, and may be saturated or unsaturated, including aromatic when the indicated maximum number of carbon atoms so permits unless otherwise indicated.
  • Ci- X alkyl where x is an integer greater than 1 refers to straight- chained and branched alkyl groups wherein the number of constituent carbon atoms is in the range 1 to x. Particular alkyl groups are methyl, ethyl, n-propyl, isopropyl and t-butyl. Derived expressions such as “C 2 - 6 alkenyl”, “hydroxyCi- 6 alkyl”, “heteroarylCi -6 alkyl”, “C 2 - 6 alkynyl” and “Ci -6 alkoxy” are to be construed in an analogous manner. Most suitably, the number of carbon atoms in such groups is not more than 6.
  • halogen as used herein includes fluorine, chlorine, bromine and iodine.
  • the compounds of formula I may be in the form of pharmaceutically acceptable salts.
  • Other salts may, however, be useful in the preparation of the compounds of formula I or of their pharmaceutically acceptable salts.
  • Suitable pharmaceutically acceptable salts of the compounds of this invention include acid addition salts which may, for example, be formed by mixing a solution of the compound according to the invention with a solution of a pharmaceutically acceptable acid such as hydrochloric acid, sulphuric acid, methanesulphonic acid, benzenesulphonic acid, fumaric acid, maleic acid, succinic acid, acetic acid, benzoic acid, oxalic acid, citric acid, tartaric acid, carbonic acid or phosphoric acid.
  • a pharmaceutically acceptable salt may be formed by neutralisation of said acidic moiety with a suitable base. Examples of pharmaceutically acceptable salts thus formed include alkali metal salts such as sodium - A -
  • ammonium salts alkaline earth metal salts such as calcium or magnesium salts
  • salts formed with suitable organic bases such as amine salts (including pyridinium salts) and quaternary ammonium salts.
  • V represents a bond, CH 2 or CH 2 CH 2 .
  • V represents CH 2 .
  • X represents N.
  • X represents CR la .
  • R 3 represents H or a hydrocarbon group of up to 10 carbon atoms, or any of which optionally is substituted as defined previously.
  • hydrocarbon groups represented by R 3 include alkyl (especially Ci -6 alkyl such as methyl, ethyl, n-propyl, isopropyl, 2-methylpropyl, n-butyl, 3-methylbutyl and 3,3-dimethylbutyl); substituted alkyl (such as methoxymethyl, methylthiomethyl and 3,3,3-trifluoropropyl); alkenyl (especially C 2-6 alkenyl such as allyl and 3-methylbut-3-enyl), cycloalkyl (especially C 3-6 cycloalkyl such as cyclopropyl, cyclopentyl and cyclohexyl); cycloalkylalkyl (such as cyclopropylmethyl); aryl (such as phenyl and A- trifluoromethylphenyl) and arylalkyl (such as benzyl, 2-phenylethyl, 2-(3,4-difluorophenyl)ethy
  • groups represented by R 3 include 2- (benzyloxyethyl).
  • R 3 represents the heterocyclic group may be 5- or 6- membered and contains up to 3 heteroatoms (typically up to 2 heteroatoms) selected from N, O and S.
  • Said heterocyclic group may be aromatic (such as pyridine, thiophene or furan) or nonaromatic (such as morpholine, thiomorpholine, piperidine or pyrrolidine).
  • groups represented by R 3 include 2-(morpholin-4-yl)ethyl, 2-(2-pyridyl)ethyl, 2-(3-pyridyl)ethyl and 2-(4- pyridyl)ethyl.
  • Y represents CO 2 H or tetrazole (in particular l,2,3,4-tetrazol-5-yl), but preferably represents
  • Ar represents phenyl which is optionally substituted as defined previously.
  • Phenyl groups represented by Ar optionally bear up to 3 substituents as defined previously.
  • substituents comprise a group represented by (CH 2 ) m -Z, m is preferably 0 or 1, most typically 0.
  • Ar represents mono-substituted phenyl, the substituent aptly occupies the 4-position.
  • suitable substituents include halogen (especially Cl and F), N 3 , CF 3 , OCF 3 , OH, OMe, and (such as methyl, ethyl, n- propyl and isopropyl).
  • Preferred substituents include Cl, F, N 3 , OCF 3 , CF 3 and OMe.
  • groups represented by Ar include phenyl, 4-chlorophenyl, A- trifluoromethylphenyl, 4-fluorophenyl, 4-azidophenyl, 4-methoxyphenyl, 4-trifluoromethoxyphenyl, 2,4- bis(trifluoromethyl)phenyl, 3,4-dichlorophenyl, 2,4-dichlorophenyl, 2,4,6-trifluorophenyl and 4-iodophenyl, of which 4-trifluoromethylphenyl is particularly preferred.
  • R 1 is selected from halogen, CN, R 4 CO, CF 3 , CH 2 N(R 4 ) 2 , branched Ci.i O alkyl groups, Ci.ioalkenyl groups, and non-aromatic cyclic groups of up to 7 ring atoms of which up to 2 may be selected from N, O and S.
  • R 1 is selected from halogen (especially Cl, Br or I), CN, R 4 CO, CF 3 , CH 2 N(R 4 ) 2 , branched Ci.i O alkyl groups (in particular branched Ci -6 alkyl groups), and non-aromatic cyclic groups of up to 7 ring atoms of which up to 2 may be selected from N, O and S.
  • R 1 typically does not represent halogen, CN or R 4 CO.
  • R 4 is typically phenyl or such as methyl or ethyl, and in a particular embodiment R 1 is benzoyl.
  • branched alkyl groups represented by R 1 include isopropyl, isobutyl, sec-butyl, tert-butyl and neopentyl.
  • Cyclic groups represented by R 1 may be carbocyclic (such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl) or heterocyclic (such as tetrahydropyranyl).
  • the cyclic group is selected from cyclobutyl, cyclopentyl, cyclohexyl and tetrahydropyran-4-yl.
  • R 4 groups very suitably complete a ring as defined previously.
  • rings represented by N(R 4 ) 2 include pyrrolidinyl, piperidinyl, morpholinyl, thiomorpholinyl, 4- methylpiperazinyl, 4-phenylpiperazinyl and 4-trifluoromethyl-l,2,3,6-tetrahydropyridinyl.
  • R 1 represents morpholin-4-ylmethyl.
  • one R 4 group very suitably represents H or and the other represents a hydrocarbon group of up to 7 carbon atoms, such as Ci -6 alkyl, C 3-
  • X is CR la and R 1 and R la complete a fused cycloalkene ring of 5, 6 or 7 members which is optionally substituted with up to 2 groups.
  • R 1 and R la may complete a fused cyclohexene ring, and the compound of formula I is thus an octahydrocarbazole derivative.
  • the fused cycloalkene ring is unsubstituted.
  • the fused cycloalkene ring is substituted with up to two groups, e.g. methyl groups.
  • R la represents H or or combines with R 1 as described above.
  • Suitable alkyl groups include methyl, ethyl and isopropyl, in particular methyl.
  • R la represents and R 1 represents halogen, CN or R 4 CO.
  • R la represents H and R 1 represents CF 3 , a branched alkyl group or a carbocyclic or heterocyclic group as described above, with the proviso that R 1 is not tert-butyl.
  • Each R 2 is independently H or such as methyl or ethyl.
  • Preferably one R 2 is H and the other is H or methyl.
  • both R 2 groups are H.
  • R 6 represents linear or branched Ci -6 alkyl (preferably such as methyl, ethyl, n-propyl, isopropyl or t-butyl, C 2-6 alkenyl such as vinyl or allyl, or phenyl, heteroaryl or benzyl which is optionally substituted as defined previously.
  • Preferred substituents include halogen (especially Cl or F), OCH 3 , OCF 3 , CF 3 and (such as methyl).
  • a preferred heteroaryl group is pyridyl, especially 3-pyridyl.
  • R 6 examples include methyl, ethyl, isopropyl, vinyl, 3-pyridyl, phenyl, 4-chlorophenyl, 3-fluorophenyl, 4-fluorophenyl, 4-fluoro-3-methylphenyl, 4-methoxyphenyl, 3,4- dichlorophenyl, 3,4-difluorophenyl and 2,5-dimethylphenyl.
  • Preferred examples include 4-fluorophenyl.
  • An R 6 group may be attached at any available position of the ring, including the carbon atom bearing the -C(R 2 ) 2 -Y moiety and any carbon atom included in V.
  • R 6 groups may be the same or different and may be attached to the same or different ring positions.
  • p is 2
  • preferably not more than one of the R 6 groups is optionally-substituted phenyl, heteroaryl or benzyl. In a particular embodiment, p is zero.
  • R 1 , R la , and R 3 have the same definitions and preferred identities as before.
  • a subset of the compounds in accordance with formula II consists of the compounds in which R 1 is Cl, Br, I, CN, CH 3 CO, PhCO or CH 2 N(R 4 ) 2 and R la is
  • R la is H and R 1 is CF 3 , a branched Ci -6 alkyl group, or a C 3-7 cycloalkyl group, or is tetrahydropyran-4-yl, with the proviso that R 1 is not tert-butyl.
  • Ar is very suitably 4-trifluoromethylphenyl.
  • a second subset of the compounds of formula I is defined by formula III:
  • n O, 1 or 2
  • R 7 is (eg. methyl)
  • Ar and R 3 have the same definitions and preferred identities as before.
  • Ar preferably represents 4-trifluoromethylphenyl.
  • R 11 represents CF 3 , branched Ci -6 alkyl, C 3-7 cycloalkyl or tetrahydropyran-4-yl, and Ar, and R 3 have the same definitions and preferred identities as before.
  • Ar is very suitably 4-trifluoromethylphenyl.
  • R 11 is t-butyl. In another subset, R 11 is branched Ci -6 alkyl that is other than t-butyl. In a third subset, R 11 is C 3-7 cycloalkyl.
  • Ar' represents a phenyl, naphthyl or heteroaryl ring system of up to 10 ring atoms up to 3 of which are selected from N, O and S, any of which ring systems optionally bearing up to 3 substituents selected from halogen, NO 2 , CF 3 , OCF 3 , CN,
  • Hal represents Cl, Br or I; each R represents H or or the two R groups together complete a cyclic boronate ester; R lb represents and
  • the reaction is an example of the Suzuki reaction and may be carried out in the presence of a Pd(II) catalyst such as bis(diphenylphosphino)ferrocene dichloropalladium(II) (Pd(dppi)Cl 2 ) in the presence of base (such as sodium carbonate) in an aqueous organic mixture such as aqueous dioxan at elevated temperature (e.g. 100 0 C, or about 17O 0 C with microwave heating).
  • a Pd(II) catalyst such as bis(diphenylphosphino)ferrocene dichloropalladium(II) (Pd(dppi)Cl 2 )
  • base such as sodium carbonate
  • aqueous organic mixture such as aqueous dioxan at elevated temperature (e.g. 100 0 C, or about 17O 0 C with microwave heating).
  • the carboxylic acid in formula VI is protected (e.g as a methyl or ethyl ester) prior to
  • Hal preferably represents Br or I.
  • Heteroaryl groups represented by Ar' may be monocyclic or bicyclic, such as pyrrole, furan, thiophene, oxazole, isoxazole, thiazole, isothiazole, pyrazole, imidazole, triazole, oxadiazole, thiadiazole, pyridine, pyrimidine, pyrazine, pyridazine, indole, benzofuran, benzothiazole, quinoline and isoquinoline.
  • said substituent(s) are typically selected from halogen (especially Cl or F), CF 3 , OCF 3 , CN and (especially methyl).
  • Ar represents 4-trifluoromethylphenyl, R 3 represents 3-methylbutyl, R lb represents isopropyl and Ar' represents 4-pyridyl; or wherein Ar represents 4-trifluoromethylphenyl, R 3 represents 3-methylbutyl, R lb represents methyl and Ar' represents 4-(trifluoromethyl)phenyl, 2,4-difluorophenyl, 4-chlorophenyl, 4- (trifluoromethoxy)phenyl, 2,4-dichlorophenyl, 2-(trifluoromethyl)phenyl, 3,4-dichlorophenyl, 2,3- dichlorophenyl, 2,5-difluorophenyl, 2,5-dichlorophenyl, 5-indolyl, 6-quinolyl, 7-thiophenyl, 5-pyrimidinyl or 4-pyrazolyl.
  • These and other compounds in accordance with formula V may be used in the same manner and for the same therapeutic purposes as the compounds of formula I as
  • Imines of formula (1) are conveniently generated in situ by reaction of an amine (3) with a cyclohexanone of formula (4):
  • reaction can be carried out in toluene with azeotropic removal of water.
  • Amines (3) may be obtained by treating ketones Ar-CO-R 3 with hydroxylamine and hydrogenating the resulting oximes over Raney nickel.
  • ketones Ar-CO-R 3 may be condensed with ⁇ - methylbenzylamine and the resulting imines reduced (using NaBH 4 ) to provide bis(benzylamines) ArCH(R 3 )-NH-CH(CH 3 )Ph, from which the desired amines (3) are obtained by hydrogenation over Pd/C.
  • Use of a chiral ⁇ -methylbenzylamine facilitates isolation of amines (3) as single enantiomers, enabling control of the stereochemistry at one of the chiral centres in formula I.
  • the reaction takes place in toluene solution in the presence of an acid catalyst (eg. acetic acid) with azeotropic removal of water.
  • an acid catalyst eg. acetic acid
  • the reaction can be carried out in dichloromethane at -78 0 C in the presence of triethylamine and TiCl 4 .
  • Enamines (6) are formed from ketones (4) by refluxing with pyrrolidine in toluene solution using an acid catalyst such as acetic acid with azeotropic removal of water.
  • a preferred route to dicarbonyl compounds (5) comprises oxidative cleavage of olefins (7):
  • V, Y, p, R 1 , R la , R 2 and R 6 have the same meanings as before.
  • the cleavage may be effected by ozonolysis in methanol/dichloromethane, or alternatively by treatment with RuCl 3 and NaIO 4 . Ozonolysis is preferred when R la is H.
  • Olefins (7) may be obtained by treatment of ketones (4) with triethylorthoformate, and reaction of the resulting diethyl ketals with an allylic alcohol (8):
  • R 1 and R la have the same meanings as before.
  • the reaction may be carried out at about 125 0 C in the presence of propionic acid.
  • the initial product is an enol ether which undergoes Claisen rearrangement to provide the olefin (7).
  • a preferred route to compounds of formula IV comprises N-alkylation of tetrahydroindazoles (11) with Ar-CH(R 3 )-Hal, followed by oxidation of the allyl group to the corresponding carboxylic acid:
  • Compounds of formula I in which R 1 is halogen, CN or R 4 CO may be obtained by reaction of the corresponding compounds in which R 1 is H with, respectively, an N-halosuccinimide, chlorosulfonyl isocyanate or R 4 COCl.
  • the reaction with N-bromo- or N-chlorosuccinimide may be carried out at -78 0 C in THF, and the reaction with N-iodosuccinimide at -2O 0 C in THF.
  • the reaction with chlorosulfonyl isocyanate may be carried out at -78 0 C in DMF/acetonitrile mixture, and the reaction with R 4 COCl may be carried out in dichloromethane in the presence OfAlCl 3 at ambient temperature.
  • the compounds of formula I in which R 1 is H are obtainable by analogous routes to those described above in which R 1 is alkyl, alkenyl, cycloalkyl or heterocyclyl.
  • a carboxylic acid group represented by Y is preferably protected as the methyl ester or ethyl ester, the free acid being regenerated by hydrolysis in a final step, e.g. using LiOH in aqueous THF or dioxan.
  • the compounds of Formula I have at least one asymmetric centre, they accordingly exist in enantiomeric forms.
  • the individual enantiomers may be isolated in pure form by conventional means.
  • a racemic mixture may be resolved into its component enantiomers by preparative chiral HPLC, or by treatment with an optically pure amine to form diastereomeric salt pairs, separable by fractional crystallisation, from which the optically pure acids may be regenerated.
  • a racemic acid may be reacted with an optically pure alcohol or amine to form pairs of diastereomeric esters or amides which may be separated by chromatography or fractional crystallisation and hydrolysed to yield enantiomerically-pure acids.
  • the invention further provides a pharmaceutical composition
  • a pharmaceutical composition comprising compound of formula I or pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier.
  • compositions are in unit dosage forms such as tablets, pills, capsules, powders, granules, sterile parenteral solutions or suspensions, metered aerosol or liquid sprays, drops, ampoules, transdermal patches, auto-injector devices or suppositories; for oral, parenteral, intranasal, sublingual or rectal administration, or for administration by inhalation or insufflation.
  • the principal active ingredient typically is mixed with a pharmaceutical carrier, e.g.
  • a tableting ingredient such as corn starch, lactose, sucrose, sorbitol, talc, stearic acid, magnesium stearate and dicalcium phosphate, or gums, dispersing agents, suspending agents or surfactants such as sorbitan monooleate and polyethylene glycol, and other pharmaceutical diluents, e.g. water, to form a homogeneous preformulation composition containing a compound of the present invention, or a pharmaceutically acceptable salt thereof.
  • these preformulation compositions as homogeneous, it is meant that the active ingredient is dispersed evenly throughout the composition so that the composition may be readily subdivided into equally effective unit dosage forms such as tablets, pills and capsules.
  • This preformulation composition is then subdivided into unit dosage forms of the type described above containing from 0.1 to about 500 mg of the active ingredient of the present invention.
  • Typical unit dosage forms contain from 1 to 100 mg, for example 1, 2, 5, 10, 25, 50 or 100 mg, of the active ingredient.
  • Tablets or pills of the composition can be coated or otherwise compounded to provide a dosage form affording the advantage of prolonged action.
  • the tablet or pill can comprise an inner dosage and an outer dosage component, the latter being in the form of an envelope over the former.
  • the two components can be separated by an enteric layer which serves to resist disintegration in the stomach and permits the inner component to pass intact into the duodenum or to be delayed in release.
  • Suitable dispersing or suspending agents for aqueous suspensions include synthetic and natural gums such as tragacanth, acacia, alginate, dextran, sodium carboxymethylcellulose, methylcellulose, poly(ethylene glycol), poly(vinylpyrrolidone) or gelatin.
  • the invention also provides a compound of formula I or a pharmaceutically acceptable salt thereof for use in therapy, in particular for use in treatment or prevention of a disease associated with deposition of
  • the invention further provides the use of a compound of formula I or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for treatment or prevention of a disease associated with deposition of A ⁇ in the brain.
  • the disease associated with deposition of A ⁇ in the brain is typically Alzheimer's disease (AD), cerebral amyloid angiopathy, multi-infarct dementia, dementia pugilistica or Down syndrome, preferably AD.
  • AD Alzheimer's disease
  • cerebral amyloid angiopathy multi-infarct dementia
  • dementia pugilistica dementia pugilistica or Down syndrome
  • the invention provides the use of a compound of Formula I as defined above, or a pharmaceutically acceptable salt thereof, in the manufacture of a medicament for treating, preventing or delaying the onset of dementia associated with Alzheimer's disease, cerebral amyloid angiopathy,
  • the invention also provides a method of treating or preventing a disease associated with deposition of A ⁇ in the brain comprising administering to a patient in need thereof a therapeutically effective amount of a compound of Formula I as defined above or a pharmaceutically acceptable salt thereof.
  • the invention provides a method of treating, preventing or delaying the onset of dementia associated with Alzheimer's disease, cerebral amyloid angiopathy, HCHWA-D, multi-infarct dementia, dementia pugilistica or Down syndrome comprising administering to a patient in need thereof a therapeutically effective amount of a compound of Formula I as defined above or a pharmaceutically acceptable salt thereof.
  • the compounds of Formula I modulate the action of ⁇ -secretase so as to selectively attenuate production of the (1-42) isoform of A ⁇ without significantly lowering production of the shorter chain isoforms such as A ⁇ (l-40). This results in secretion of A ⁇ which has less tendency to self-aggregate and form insoluble deposits, is more easily cleared from the brain, and/or is less neurotoxic. Therefore, a further aspect of the invention provides a method for retarding, arresting or preventing the accumulation of A ⁇ in the brain comprising administering to a subject in need thereof a therapeutically effective amount of a compound of Formula I as defined above or a pharmaceutically acceptable salt thereof.
  • the compounds of formula I modulate the activity of ⁇ -secretase, as opposed to suppressing said activity, it is believed that the therapeutic benefits described above will be obtained with a reduced risk of side effects, e.g. those that might arise from a disruption of other signalling pathways (e.g. Notch) which are also controlled by ⁇ -secretase.
  • side effects e.g. those that might arise from a disruption of other signalling pathways (e.g. Notch) which are also controlled by ⁇ -secretase.
  • the compound of Formula I is administered to a patient suffering from AD, cerebral amyloid angiopathy, HCHWA-D, multi-infarct dementia, dementia pugilistica or Down syndrome, preferably AD.
  • the compound of Formula I is administered to a patient suffering from mild cognitive impairment or age-related cognitive decline.
  • a favourable outcome of such treatment is prevention or delay of the onset of AD.
  • Age-related cognitive decline and mild cognitive impairment (MCI) are conditions in which a memory deficit is present, but other diagnostic criteria for dementia are absent (Santacruz and Swagerty, American Family Physician, 63 (2001), 703-13).
  • age-related cognitive decline implies a decline of at least six months' duration in at least one of: memory and learning; attention and concentration; thinking; language; and visuospatial functioning and a score of more than one standard deviation below the norm on standardized neuropsychologic testing such as the MMSE. In particular, there may be a progressive decline in memory. In the more severe condition MCI, the degree of memory impairment is outside the range considered normal for the age of the patient but AD is not present. The differential diagnosis of MCI and mild AD is described by Petersen et ah, Arch. Neurol, 56 (1999), 303-8.
  • the compound of Formula I is advantageously administered to patients who suffer impaired memory function but do not exhibit symptoms of dementia. Such impairment of memory function typically is not attributable to systemic or cerebral disease, such as stroke or metabolic disorders caused by pituitary dysfunction.
  • Such patients may be in particular people aged 55 or over, especially people aged 60 or over, and preferably people aged 65 or over. Such patients may have normal patterns and levels of growth hormone secretion for their age. However, such patients may possess one or more additional risk factors for developing Alzheimer's disease. Such factors include a family history of the disease; a genetic predisposition to the disease; elevated serum cholesterol; and adult-onset diabetes mellitus.
  • the compound of Formula I is administered to a patient suffering from age-related cognitive decline or MCI who additionally possesses one or more risk factors for developing AD selected from: a family history of the disease; a genetic predisposition to the disease; elevated serum cholesterol; adult-onset diabetes mellitus; elevated baseline hippocampal volume; elevated CSF levels of total tau; elevated CSF levels of phospho-tau; and lowered CSF levels of A ⁇ (l-42).
  • a genetic predisposition (especially towards early onset AD) can arise from point mutations in one or more of a number of genes, including the APP, presenilin-1 and presenilin-2 genes.
  • subjects who are homozygous for the ⁇ 4 isoform of the apolipoprotein E gene are at greater risk of developing AD.
  • the patient's degree of cognitive decline or impairment is advantageously assessed at regular intervals before, during and/or after a course of treatment in accordance with the invention, so that changes therein may be detected, e.g. the slowing or halting of cognitive decline.
  • a variety of neuropsychological tests are known in the art for this purpose, such as the Mini-Mental State Examination (MMSE) with norms adjusted for age and education (Folstein et al, J. Psych.
  • MMSE Mini-Mental State Examination
  • the MMSE is a brief, quantitative measure of cognitive status in adults. It can be used to screen for cognitive decline or impairment, to estimate the severity of cognitive decline or impairment at a given point in time, to follow the course of cognitive changes in an individual over time, and to document an individual's response to treatment.
  • ADAS Alzheimer Disease Assessment Scale
  • ADAS-cog the cognitive element thereof
  • a suitable dosage level is about 0.01 to 250 mg/kg per day, preferably about 0.01 to 100 mg/kg per day, and more preferably about 0.05 to 50 mg/kg of body weight per day, of the active compound.
  • the compounds may be administered on a regimen of 1 to 4 times per day. In some cases, however, a dosage outside these limits may be used.
  • the compounds of Formula I optionally may be administered in combination with one or more additional compounds known to be useful in the treatment or prevention of AD or the symptoms thereof.
  • additional compounds thus include cognition-enhancing drugs such as acetylcholinesterase inhibitors (e.g. donepezil and galanthamine), NMDA antagonists (e.g.
  • Such additional compounds also include cholesterol-lowering drugs such as the statins, e.g. simvastatin.
  • additional compounds similarly include compounds known to modify the production or processing of A ⁇ in the brain ("amyloid modifiers"), such as compounds which inhibit the secretion of A ⁇ (including ⁇ -secretase inhibitors, ⁇ -secretase inhibitors, and GSK-3 ⁇ inhibitors), compounds which inhibit the aggregation of A ⁇ , and antibodies which selectively bind to A ⁇ .
  • additional compounds further include growth hormone secretagogues, e.g. as described in WO 2004/110443 and WO 2004/080459.
  • the amyloid modifier may be a compound which inhibits the secretion of A ⁇ , for example an inhibitor of ⁇ -secretase (such as those disclosed in WO 01/53255, WO 01/66564, WO 01/70677, WO 01/90084, WO 01/77144, WO 02/30912, WO 02/36555, WO 02/081435, WO 02/081433, WO 03/018543, WO 03/013506, WO 03/013527, WO 03/014075, WO 03/093251, WO 03/093252, WO 03/093253, WO 03/093264, WO 2004/031137, WO 2004/031138, WO 2004/031139, WO 2004/039370, WO 2004/039800, WO 2004/101538, WO 2004/101539 and WO 2005/030731), or a ⁇ -secretase inhibitor (such as those disclosed in WO 03/03255, WO 01
  • the amyloid modifier may be a compound which inhibits the aggregation of A ⁇ or otherwise attenuates is neurotoxicicity.
  • Suitable examples include chelating agents such as clioquinol (Gouras and Beal, Neuron, 30 (2001), 641-2) and the compounds disclosed in WO 99/16741, in particular that known as DP-109 (Kalendarev et al, J. Pharm. Biomed. Anal, 24 (2001), 967-75).
  • inhibitors of A ⁇ aggregation suitable for use in the invention include the compounds disclosed in WO 96/28471, WO 98/08868 and WO 00/052048, including the compound known as ApanTM (Praecis); WO 00/064420, WO 03/017994, WO 99/59571 (in particular 3-aminopropane-l -sulfonic acid, also known as tramiprosate or AlzhemedTM); WO 00/149281 and the compositions known as PTI-777 and PTI-00703 (ProteoTech); WO 96/39834, WO 01/83425, WO 01/55093, WO 00/76988, WO 00/76987, WO 00/76969, WO 00/76489, WO 97/26919, WO 97/16194, and WO 97/16191.
  • Further examples include phytic acid derivatives as disclosed in US 4,847,082 and inos
  • the amyloid modifier may be an antibody which binds selectively to A ⁇ .
  • Said antibody may be polyclonal or monoclonal, but is preferably monoclonal, and is preferably human or humanized.
  • the antibody is capable of sequestering soluble A ⁇ from biological fluids, as described in WO 03/016466, WO 03/016467, WO 03/015691 and WO 01/62801.
  • Suitable antibodies include humanized antibody 266 (described in WO 01/62801) and the modified version thereof described in WO 03/016466.
  • Suitable antibodies also include those specific to A ⁇ -derived diffusible ligands (ADDLS), as disclosed in WO 2004/031400.
  • ADDLS A ⁇ -derived diffusible ligands
  • the expression "in combination with” requires that therapeutically effective amounts of both the compound of Formula I and the additional compound are administered to the subject, but places no restriction on the manner in which this is achieved.
  • the two species may be combined in a single dosage form for simultaneous administration to the subject, or may be provided in separate dosage forms for simultaneous or sequential administration to the subject. Sequential administration may be close in time or remote in time, e.g. one species administered in the morning and the other in the evening.
  • the separate species may be administered at the same frequency or at different frequencies, e.g. one species once a day and the other two or more times a day.
  • the separate species may be administered by the same route or by different routes, e.g. one species orally and the other parenterally, although oral administration of both species is preferred, where possible.
  • the additional compound is an antibody, it will typically be administered parenterally and separately from the compound of Formula I.
  • Human SH-SY5Y neuroblastoma cells overexpressing the direct ⁇ -secretase substrate SPA4CT were induced with sodium butyrate (10 mM) for 4 hours prior to plating.
  • Cells were plated at 35,000 cells/well/100 ⁇ l in 96-well plates in phenol red-free MEM/10% FBS, 50 mM HEPES, 1% Glutamine and incubated for 2 hrs at 37 0 C, 5% CO 2 .
  • a ⁇ (40) premix 1 ⁇ g/ml ruthenylated G2-10 antibody, 4 ⁇ g/ml biotinylated 4G8 antibody diluted in Origen buffer
  • a ⁇ (42) premix 0.5 ⁇ g/ml ruthenylated G2-11 antibody, 4 ⁇ g/ml biotinylated 4G8 antibody diluted in Origen buffer
  • LD 50 and IC 50 values for inhibition of A ⁇ (40) and A ⁇ (42) were calculated by nonlinear regression fit analysis using the appropriate software (eg. Excel fit). The total signal and the background were defined by the corresponding Me 2 SO and inhibitor controls.
  • the compounds of the invention give IC 50 values for A ⁇ (l-42) inhibition that are at least 2-fold lower than the corresponding IC 50 values for A ⁇ (l-40) inhibition, typically at least 5-fold lower, and in the preferred cases at least 50-fold lower.
  • Step 2 To a solution of ⁇ 4-methyl-l-[4-(trifluoromethyl)phenyl]pentylidene ⁇ [(liS)-l-phenylethyl]amine [Step 2] (87 g, 0.25 mol) in methanol (0.5 L) at -20 0 C was added sodium borohydride (10 g, 0.263 mol) portionwise. The solution was stirred 1/2 hrs at O 0 C and quenched carefully with IN HCl , basif ⁇ ed with 4N NaOH and extracted with EtOAc.
  • Step 2 To a vigorously stirred suspension of ethyl [3-(2-methylprop-2-en-l-yl)-2-oxocyclohexyl]acetate [Step 2] (25 g, 105 mmol) and sodium periodate (89.8 g, 420 mmol) in CCl 4 (50 mL) / MeCN (50 mL) and water (75 mL) was added ruthenium trichloride monohydrate (0.44 g, 2.1 mmol), and stirring was continued for 16 h. The resulting mixture was partitioned between water (850 mL) and DCM (850 mL), and the aqueous layer/solid residue was extracted with DCM (x2).
  • Step 3 The product of Step 3 (2.0 g, 8.33 mmol), Intermediate 2 (2.04 g, 8.33 mmol) and 4-methy ⁇ benzenesulfonic acid hydrate (0.16 g, 0.83 mmol) were dissolved in toluene (7 mL) and heated to 15O 0 C for 48 h with a Dean-Stark trap. The mixture was cooled, and partitioned between DCM and NaHCO 3 (aq). The organic phase was dried (sodium sulfate), and concentrated under reduced pressure to give a dark brown oil, which was purified by flash chromatography (Biotage SPl, 4OM, 0->15% EtOAc/ isohexane) to give a pale yellow oil.
  • Step 2 The product of Step 1 (25 mg, 0.05 mmol), was dissolved in EtOH (3 mL), and 0.5M NaOH(aq) (0.29 mL) was added. After stirring at RT for 2 h, the solvent was removed under reduced pressure, and the residue was partitioned between 2M HCl (aq)/DCM, filtered through a phase-separation cartridge and concentrated. Purification by flash chromatography (Biotage SPl, 25S, 20->75% EtOAc/isohexane) gave a white foam, (15 mg, 63%).
  • Step 1 Sodium hydride, 60% dispersion in oil (13.9 g, 34.8 mmol) was added portionwise to dimethoxyethane (300 mL) with water cooling. Triethyl phosphonoacetate (69 mL, 34.8 mmol) was added slowly. The mixture was stirred for 90 minutes at RT. Cyclohexanecarboxaldehyde (15 g, 13.4 mmol) was added and the mixture was stirred at RT for 18 h. Water (200 mL) was added and the mixture was extracted with ether. The organic phase was washed with brine, dried over sodium sulphate and concentrated to dryness. The residue was purified by column chromatography (40:1 isohexane-ethyl acetate) to give an oil (19.8 g, 79 %).
  • Step 2 DIBAH, IM in hexanes (268 mL, 26.8 mmol) was added dropwise to a stirred solution of the product of Step 1 (19.5 g, 10.7 mmol) in ether (25 mL) maintaining the temperature below -70 0 C.
  • the mixture was stirred at -78°C for 3 h and then quenched with methanol followed by sat. ammonium chloride solution.
  • the mixture was allowed to warm to RT, diluted with ether and washed with 2M HCl.
  • the organic phase was washed with water and then brine, dried over sodium sulphate and concentrated to give a colourless oil (12.3 g, 82 %).
  • Step 4 Nitrogen was bubbled into a stirred solution of the product of Step 3 (703 mg, 2.28 mmol) in DCM (40 mL) at -78°C for a few minutes. Oxygen was then bubbled into the mixture followed by ozone. A blue colour persisted after a few minutes.
  • Step 5 A mixture of product from Step 4 (774 mg, 2.51 mmol), Intermediate 2 (739 mg, 3.01 mmol), lithium perchlorate (266 mg, 2.51 mmol) and acetic acid (0.4 ml) in toluene (25 ml) was stirred and heated under reflux in a flask equipped with a Dean-Stark apparatus for 20 h. After cooling to RT and dilution with EtOAc, the mixture was washed with sat. NaHCO 3 solution and brine, dried over sodium sulphate and concentrated to dryness.
  • the chromatographed material was separated into single diastereomers using preparative HPLC (HIRPB column 250 x 20 mm id, 85% MeCN and 15% TFA (0.1%) in water, 20 ml/min).
  • the first eluted compound was designated diastereomer 1 (61 mg).
  • the second eluted compound was designated diastereomer 2 (60 mg).
  • Examples 10-11 were made in analogous fashion to Example 5 starting from the appropriate aldehyde and using Intermediate 1 in Step 5 in place of Intermediate 2.
  • Step 2 The product of Step 2 was treated as in Example 5 Steps 4-6 to provide the title compound, m/z ES " (M- H + ) 490.
  • Example 13 (3-Trifluoromethyl)- 1 - ⁇ (lJ?)-4-methyl- 1 -[4-(trifluoromethyl) phenyl]pentyl ⁇ -4,5,6,7-tetrahydro- lH-indol- 7-yl)acetic acid
  • Step 3 The product of Step 3 was hydrolysed as described in Example 1 Step 2.
  • the product was purified by flash chromatography (SiO 2 , 9:1->2:1 isohexane:EtOAc) to give the product as a mixture of diastereoisomers.
  • the diastereoisomers were separated using reverse-phase preparative HPLC.
  • Step 1 7-Allyl-3-(l.l-dimethylethyl)-4.5.6.7-tetrahvdro-lH-indazole: A IM solution of lithium hexamethyldisilazide in THF (40 mL, 0.04 mol) was added dropwise to solution of 2-allylcylohexanone (5g, 0.036 mol) in dry THF (50 mL) cooled below -70° under N 2 .
  • Step 1 was converted to the corresponding acid according to the method for Example 5, step 6.
  • Step 2 Step 1 was converted to the corresponding acid according to the method for example 5, step 6. m/z ES + (M+H + ) 496.
  • Step 1 was converted to the corresponding acid according to the method for example 5, step 6.
  • IH NMR 400 MHz, CDC13: ⁇ 7.54 (d, 2 H), 7.16 (t, 2 H), 5.23 (m, 1 H), 3.70 (t, 4 H), 3.42 (s, 2 H), 3.22 (d, 1 H), 2.53-0.70 (m, 26 H) m/z ES + (M+H + ) 507.
  • Step 1 The product of Step 1 was treated with N-iodosuccinimide as in Example 15 to provide the 3-iodo derivative.
  • IH NMR 500 MHz, CDC13: ⁇ 7.57 (d, 2 H), 7.14 (d, 2 H), 5.25 (dd, 1 H), 3.59 (s, 3 H), 3.23 (d, 1 H), 2.49-2.27 (m, 4 H), 2.19-2.04 (m, 2 H), 1.89 (s, 3 H), 1.82-1.65 (m, 2 H), 1.63-1.51 (m, 1 H) 1.36-1.20 (m, 2 H), 0.97-0.83 (m, 8 H).
  • Step 3 IH NMR (500 MHz, CDC13): ⁇ 7.57 (d, 2 H), 7.14 (d, 2 H), 5.25 (dd, 1 H), 3.59 (s, 3 H), 3.23 (d, 1 H), 2.49-2.27 (m, 4 H), 2.19-2.04 (m, 2 H), 1.89 (s,

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Abstract

Tetrahydroindole derivatives of formula (I): are disclosed. These compounds modulate the activity of gamma-secretase and hence find use in treatment or prevention of Alzheimer's disease.

Description

TETRAHYDROINDOLE DERIVATIVES FOR TREATMENT OF ALZHEIMER'S DISEASE
This invention relates to methods and materials for use in therapeutic treatment of the human body. In particular, it provides materials for treating diseases associated with the deposition of β-amyloid peptide in the brain, such as Alzheimer's disease, or of preventing or delaying the onset of dementia associated with such diseases.
Alzheimer's disease (AD) is the most prevalent form of dementia. Its diagnosis is described in the Diagnostic and Statistical Manual of Mental Disorders, 4th ed., published by the American Psychiatric Association (DSM-IV). It is a neurodegenerative disorder, clinically characterized by progressive loss of memory and general cognitive function, and pathologically characterized by the deposition of extracellular proteinaceous plaques in the cortical and associative brain regions of sufferers. These plaques mainly comprise fibrillar aggregates of β-amyloid peptide (Aβ). Aβ is formed from amyloid precursor protein (APP) via separate intracellular proteolytic events involving the enzymes β-secretase and γ-secretase. Variability in the site of the proteolysis mediated by γ-secretase results in Aβ of varying chain length, e.g. Aβ(l-38), Aβ(l-40) and Aβ(l-42). N-terminal truncations such as Aβ(4-42) are also found in the brain, possibly as a result of variability in the site of proteolysis mediated by β-secretase. For the sake of convenience, expressions such as "Aβ(l-40)" and "Aβ(l-42)" as used herein are inclusive of such N- terminal truncated variants. After secretion into the extracellular medium, Aβ forms initially-soluble aggregates which are widely believed to be the key neurotoxic agents in AD (see Gong et al, PNAS, 100 (2003), 10417-22), and which ultimately result in the insoluble deposits and dense neuritic plaques which are the pathological characteristics of AD.
Other dementing conditions associated with deposition of Aβ in the brain include cerebral amyloid angiopathy, hereditary cerebral haemorrhage with amyloidosis, Dutch-type (HCHWA-D), multi-infarct dementia, dementia pugilistica and Down syndrome. Various interventions in the plaque-forming process have been proposed as therapeutic treatments for AD (see, for example, Hardy and Selkoe, Science, 297 (2002), 353-6). One such method of treatment that has been proposed is that of blocking or attenuating the production of Aβ for example by inhibition of β- or γ-secretase. It has also been reported that inhibition of glycogen synthase kinase-3 (GSK-3), in particular inhibition of GSK-3α, can block the production of Aβ (see Phiel et al, Nature, 423 (2003), 435- 9). Other proposed methods of treatment include administering a compound which blocks the aggregation of Aβ, and administering an antibody which selectively binds to Aβ.
However, recent reports (Pearson and Peers, J. Physiol., 575.1 (2006), 5-10) suggest that Aβ may exert important physiological effects independent of its role in AD, implying that blocking its production may lead to undesirable side effects. Furthermore, γ-secretase is known to act on several different substrates apart from APP (e.g. notch), and so inhibition thereof may also lead to unwanted side effects. There is therefore an interest in methods of treating AD that do not suppress completely the production of Aβ, and do not inhibit the action of γ-secretase. One such proposed treatment involves modulation of the action of γ-secretase so as to selectively attenuate the production of Aβ(l-42). This results in preferential secretion of the shorter chain isoforms of Aβ, which are believed to have a reduced propensity for self-aggregation and plaque formation, and hence are more easily cleared from the brain, and/or are less neurotoxic. Compounds showing this effect include certain non-steroidal antiinflammatory drugs (NSAIDs) and their analogues (see WO 01/78721 and US 2002/0128319 and Weggen et al Nature, 414 (2001) 212-16; Morihara et al, J. Neurochem., 83 (2002), 1009-12; and Takahashi et al, J. Biol. Chem., 278 (2003), 18644-70). Compounds which modulate the activity of PP ARa and/or PPARδ are also reported to have the effect of lowering Aβ(l-42) (WO 02/100836). NSAID derivatives capable of releasing nitric oxide have been reported to show improved anti-neuroinflammatory effects and/or to reduce intracerebral Aβ deposition in animal models (WO 02/092072; Jantzen et al, J. Neuroscience, 22 (2002), 226-54). US 2002/0015941 teaches that agents which potentiate capacitative calcium entry activity can lower Aβ(l-42).
WO 2005/054193 and WO 2005/013985 disclose further classes of compounds which selectively attenuate Aβ(l-42).
It has now been found that certain tetrahydroindole alkanoic acids and related compounds have the desirable property of selectively inhibiting production of Aβ(l-42).
According to the present invention there is provided a compound of formula I:
Figure imgf000003_0001
(I) wherein V represents a bond, CH2 or CH2CH2;
X represents CRla or N;
Y represents CO2H or tetrazole;
Ar represents phenyl which optionally bears up to 3 substituents independently selected from hydrocarbon groups of up to 6 carbon atoms and (CH2)m-Z where m is 0, 1 or 2 and Z represents halogen, N3, CN, CF3, OCF3 or OR4;
R1 represents halogen, CN, R4CO, CF3, CH2N(R4)2, a branched Ci.iOalkyl group, a Ci.iOalkenyl group, or a non-aromatic cyclic group of up to 7 ring atoms of which up to 2 may be selected from N, O and S; or when X is CRla, R1 and Rla may complete a fused cycloalkene ring of 5, 6 or 7 members which is optionally substituted with up to 2
Figure imgf000003_0002
groups;
Rla represents H or
Figure imgf000003_0003
or combines with R1 as defined above; with the proviso that when X is CH, R1 is not t-butyl; each R2 is independently H or Ci^alkyl; R3 is H, hydrocarbon containing up to 10 carbon atoms,
Figure imgf000004_0001
or heterocyclylCi. 4alkyl, any of which optionally bears up to 3 substitutents selected from halogen and CF3, or 1 substituent selected from and
Figure imgf000004_0002
where "heterocyclyl" refers to aromatic or nonaromatic rings of 5 or 6 atoms of which 1, 2 or 3 are selected from N, O and S; R4 represents H or a hydrocarbon group of up to 7 carbon atoms, optionally substituted with halogen, CN, CF3, OH,
Figure imgf000004_0003
or two R4 groups attached to a nitrogen atom may complete ring selected from pyrrolidine, piperidine, morpholine, thiomorpholine, tetrahydropyridine and piperazine, any of which rings optionally bearing a substituent selected from CF3,
Figure imgf000004_0004
and phenyl;
R5 represents R4 that is other than H; p is 0, 1 or 2; and
R6 represents Ci-6alkyl, C2-6alkenyl or phenyl, benzyl or heteroaryl, said phenyl, benzyl or heteroaryl optionally bearing up to 3 substituents selected from halogen, CN, CF3, OCF3, OR4, CO2R4,
Figure imgf000004_0005
or a pharmaceutically acceptable salt or hydrate thereof. Where a variable occurs more than once in formula I or in a substituent thereof, the individual occurrences of that variable are independent of each other, unless otherwise specified.
As used herein, the expression "hydrocarbon group" refers to groups consisting solely of carbon and hydrogen atoms. Such groups may comprise linear, branched or cyclic structures, singly or in any combination consistent with the indicated maximum number of carbon atoms, and may be saturated or unsaturated, including aromatic when the indicated maximum number of carbon atoms so permits unless otherwise indicated.
As used herein, the expression "Ci-Xalkyl" where x is an integer greater than 1 refers to straight- chained and branched alkyl groups wherein the number of constituent carbon atoms is in the range 1 to x. Particular alkyl groups are methyl, ethyl, n-propyl, isopropyl and t-butyl. Derived expressions such as "C2-6alkenyl", "hydroxyCi-6alkyl", "heteroarylCi-6alkyl", "C2-6alkynyl" and "Ci-6alkoxy" are to be construed in an analogous manner. Most suitably, the number of carbon atoms in such groups is not more than 6.
The term "halogen" as used herein includes fluorine, chlorine, bromine and iodine. For use in medicine, the compounds of formula I may be in the form of pharmaceutically acceptable salts. Other salts may, however, be useful in the preparation of the compounds of formula I or of their pharmaceutically acceptable salts. Suitable pharmaceutically acceptable salts of the compounds of this invention include acid addition salts which may, for example, be formed by mixing a solution of the compound according to the invention with a solution of a pharmaceutically acceptable acid such as hydrochloric acid, sulphuric acid, methanesulphonic acid, benzenesulphonic acid, fumaric acid, maleic acid, succinic acid, acetic acid, benzoic acid, oxalic acid, citric acid, tartaric acid, carbonic acid or phosphoric acid. Alternatively, where the compound of the invention carries an acidic moiety, a pharmaceutically acceptable salt may be formed by neutralisation of said acidic moiety with a suitable base. Examples of pharmaceutically acceptable salts thus formed include alkali metal salts such as sodium - A -
or potassium salts; ammonium salts; alkaline earth metal salts such as calcium or magnesium salts; and salts formed with suitable organic bases, such as amine salts (including pyridinium salts) and quaternary ammonium salts.
Where the compounds according to the invention have at least one asymmetric centre, they may accordingly exist as enantiomers. Where the compounds according to the invention possess two or more asymmetric centres, they may additionally exist as diastereoisomers. It is to be understood that all such isomers and mixtures thereof in any proportion are encompassed within the scope of the present invention. In formula I, V represents a bond, CH2 or CH2CH2. In a particular embodiment V represents CH2. In one embodiment, X represents N. In another embodiment, X represents CRla. R3 represents H or a hydrocarbon group of up to 10 carbon atoms,
Figure imgf000005_0001
or
Figure imgf000005_0002
any of which optionally is substituted as defined previously. Examples of hydrocarbon groups represented by R3 include alkyl (especially Ci-6alkyl such as methyl, ethyl, n-propyl, isopropyl, 2-methylpropyl, n-butyl, 3-methylbutyl and 3,3-dimethylbutyl); substituted alkyl (such as methoxymethyl, methylthiomethyl and 3,3,3-trifluoropropyl); alkenyl (especially C2-6alkenyl such as allyl and 3-methylbut-3-enyl), cycloalkyl (especially C3-6cycloalkyl such as cyclopropyl, cyclopentyl and cyclohexyl); cycloalkylalkyl (such as cyclopropylmethyl); aryl (such as phenyl and A- trifluoromethylphenyl) and arylalkyl (such as benzyl, 2-phenylethyl, 2-(3,4-difluorophenyl)ethyl, 2-(3- trifluoromethylphenyl)ethyl).
Figure imgf000005_0003
groups represented by R3 include 2- (benzyloxyethyl). When R3 represents
Figure imgf000005_0004
the heterocyclic group may be 5- or 6- membered and contains up to 3 heteroatoms (typically up to 2 heteroatoms) selected from N, O and S. Said heterocyclic group may be aromatic (such as pyridine, thiophene or furan) or nonaromatic (such as morpholine, thiomorpholine, piperidine or pyrrolidine).
Figure imgf000005_0005
groups represented by R3 include 2-(morpholin-4-yl)ethyl, 2-(2-pyridyl)ethyl, 2-(3-pyridyl)ethyl and 2-(4- pyridyl)ethyl. Y represents CO2H or tetrazole (in particular l,2,3,4-tetrazol-5-yl), but preferably represents
CO2H.
Ar represents phenyl which is optionally substituted as defined previously. Phenyl groups represented by Ar optionally bear up to 3 substituents as defined previously. When said substituents comprise a group represented by (CH2)m-Z, m is preferably 0 or 1, most typically 0. When Ar represents mono-substituted phenyl, the substituent aptly occupies the 4-position. Examples of suitable substituents include halogen (especially Cl and F), N3, CF3, OCF3, OH, OMe, and
Figure imgf000005_0006
(such as methyl, ethyl, n- propyl and isopropyl). Preferred substituents include Cl, F, N3, OCF3, CF3 and OMe.
Specific examples of groups represented by Ar include phenyl, 4-chlorophenyl, A- trifluoromethylphenyl, 4-fluorophenyl, 4-azidophenyl, 4-methoxyphenyl, 4-trifluoromethoxyphenyl, 2,4- bis(trifluoromethyl)phenyl, 3,4-dichlorophenyl, 2,4-dichlorophenyl, 2,4,6-trifluorophenyl and 4-iodophenyl, of which 4-trifluoromethylphenyl is particularly preferred.
In one embodiment, R1 is selected from halogen, CN, R4CO, CF3, CH2N(R4)2, branched Ci.iOalkyl groups, Ci.ioalkenyl groups, and non-aromatic cyclic groups of up to 7 ring atoms of which up to 2 may be selected from N, O and S. In a subset of this embodiment, R1 is selected from halogen (especially Cl, Br or I), CN, R4CO, CF3, CH2N(R4)2, branched Ci.iOalkyl groups (in particular branched Ci-6alkyl groups), and non-aromatic cyclic groups of up to 7 ring atoms of which up to 2 may be selected from N, O and S.
When X is N, R1 typically does not represent halogen, CN or R4CO. When R1 represents R4CO, R4 is typically phenyl or
Figure imgf000006_0001
such as methyl or ethyl, and in a particular embodiment R1 is benzoyl. Examples of branched alkyl groups represented by R1 include isopropyl, isobutyl, sec-butyl, tert-butyl and neopentyl. Cyclic groups represented by R1 may be carbocyclic (such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl) or heterocyclic (such as tetrahydropyranyl). In a particular embodiment the cyclic group is selected from cyclobutyl, cyclopentyl, cyclohexyl and tetrahydropyran-4-yl.
When R1 represents CH2N(R4)2, the R4 groups very suitably complete a ring as defined previously. Examples of rings represented by N(R4)2 include pyrrolidinyl, piperidinyl, morpholinyl, thiomorpholinyl, 4- methylpiperazinyl, 4-phenylpiperazinyl and 4-trifluoromethyl-l,2,3,6-tetrahydropyridinyl. In a particular embodiment, R1 represents morpholin-4-ylmethyl. Alternatively, one R4 group very suitably represents H or and the other represents a hydrocarbon group of up to 7 carbon atoms, such as Ci-6alkyl, C3-
6cycloalkyl, phenyl or benzyl, optionally substituted as defined previously. Examples of groups represented by CH2N(R4)2 thus include anilinomethyl, benzylaminomethyl and cyclohexylaminomethyl.
In another embodiment, X is CRla and R1 and Rla complete a fused cycloalkene ring of 5, 6 or 7 members which is optionally substituted with up to 2
Figure imgf000006_0002
groups. For example, R1 and Rla may complete a fused cyclohexene ring, and the compound of formula I is thus an octahydrocarbazole derivative. In a particular embodiment, the fused cycloalkene ring is unsubstituted. In another particular embodiment, the fused cycloalkene ring is substituted with up to two
Figure imgf000006_0003
groups, e.g. methyl groups.
When present, Rla represents H or
Figure imgf000006_0004
or combines with R1 as described above. Suitable alkyl groups include methyl, ethyl and isopropyl, in particular methyl. In one embodiment, Rla represents and R1 represents halogen, CN or R4CO. In a further embodiment, Rla represents H and R1 represents CF3, a branched alkyl group or a carbocyclic or heterocyclic group as described above, with the proviso that R1 is not tert-butyl.
Each R2 is independently H or
Figure imgf000006_0005
such as methyl or ethyl. Preferably one R2 is H and the other is H or methyl. Most preferably, both R2 groups are H. When present, R6 represents linear or branched Ci-6alkyl (preferably
Figure imgf000006_0006
such as methyl, ethyl, n-propyl, isopropyl or t-butyl, C2-6 alkenyl such as vinyl or allyl, or phenyl, heteroaryl or benzyl which is optionally substituted as defined previously. Preferred substituents include halogen (especially Cl or F), OCH3, OCF3, CF3 and
Figure imgf000006_0007
(such as methyl). A preferred heteroaryl group is pyridyl, especially 3-pyridyl. Examples of groups represented by R6 include methyl, ethyl, isopropyl, vinyl, 3-pyridyl, phenyl, 4-chlorophenyl, 3-fluorophenyl, 4-fluorophenyl, 4-fluoro-3-methylphenyl, 4-methoxyphenyl, 3,4- dichlorophenyl, 3,4-difluorophenyl and 2,5-dimethylphenyl. Preferred examples include 4-fluorophenyl. An R6 group may be attached at any available position of the ring, including the carbon atom bearing the -C(R2)2-Y moiety and any carbon atom included in V. Where two R6 groups are present, they may be the same or different and may be attached to the same or different ring positions. When p is 2, preferably not more than one of the R6 groups is optionally-substituted phenyl, heteroaryl or benzyl. In a particular embodiment, p is zero.
A subset of the compounds of Formula I is defined by Formula II:
Figure imgf000007_0001
π
wherein Ar, R1, Rla, and R3 have the same definitions and preferred identities as before.
A subset of the compounds in accordance with formula II consists of the compounds in which R1 is Cl, Br, I, CN, CH3CO, PhCO or CH2N(R4)2 and Rla is
Figure imgf000007_0002
Another subset of the compounds of formula II consists of those in which Rla is H and R1 is CF3, a branched Ci-6alkyl group, or a C3-7cycloalkyl group, or is tetrahydropyran-4-yl, with the proviso that R1 is not tert-butyl.
In both of these subsets of formula II, Ar is very suitably 4-trifluoromethylphenyl. A second subset of the compounds of formula I is defined by formula III:
Figure imgf000007_0003
III
wherein n is O, 1 or 2, R7 is
Figure imgf000007_0004
(eg. methyl), and Ar and R3 have the same definitions and preferred identities as before. In formula III, Ar preferably represents 4-trifluoromethylphenyl. A third subset of the compounds of formula I is defined by formula IV:
Figure imgf000008_0001
IV
where R11 represents CF3, branched Ci-6alkyl, C3-7cycloalkyl or tetrahydropyran-4-yl, and Ar, and R3 have the same definitions and preferred identities as before.
In formula IV, Ar is very suitably 4-trifluoromethylphenyl.
In one subset of formula FV, R11 is t-butyl. In another subset, R11 is branched Ci-6alkyl that is other than t-butyl. In a third subset, R11 is C3-7cycloalkyl.
Compounds of formula II in which R1 represents Cl, Br or I and Rla is
Figure imgf000008_0002
have a particular utility as starting materials for the synthesis of further compounds having the property of selectively inhibiting the production of Aβ(l-42), e.g. compounds of a type disclosed in WO2005/108362. Therefore, according to a further aspect of the invention, there is provided a process for preparing a compound of formula V:
Figure imgf000008_0003
comprising reaction of compound of formula VI
Figure imgf000008_0004
with a boronic acid derivative Ar'-B(OR)2; wherein:
Ar' represents a phenyl, naphthyl or heteroaryl ring system of up to 10 ring atoms up to 3 of which are selected from N, O and S, any of which ring systems optionally bearing up to 3 substituents selected from halogen, NO2, CF3, OCF3, CN,
Figure imgf000008_0005
Hal represents Cl, Br or I; each R represents H or
Figure imgf000008_0006
or the two R groups together complete a cyclic boronate ester; Rlb represents
Figure imgf000009_0001
and
Ar and R3 have the same definitions and preferred identities as before. The reaction is an example of the Suzuki reaction and may be carried out in the presence of a Pd(II) catalyst such as bis(diphenylphosphino)ferrocene dichloropalladium(II) (Pd(dppi)Cl2) in the presence of base (such as sodium carbonate) in an aqueous organic mixture such as aqueous dioxan at elevated temperature (e.g. 1000C, or about 17O0C with microwave heating). Very suitably, the carboxylic acid in formula VI is protected (e.g as a methyl or ethyl ester) prior to the reaction, and regenerated subsequently (e.g. by alkaline hydrolysis).
Hal preferably represents Br or I. Heteroaryl groups represented by Ar' may be monocyclic or bicyclic, such as pyrrole, furan, thiophene, oxazole, isoxazole, thiazole, isothiazole, pyrazole, imidazole, triazole, oxadiazole, thiadiazole, pyridine, pyrimidine, pyrazine, pyridazine, indole, benzofuran, benzothiazole, quinoline and isoquinoline. When Ar' bears one or more substituents, said substituent(s) are typically selected from halogen (especially Cl or F), CF3, OCF3, CN and
Figure imgf000009_0002
(especially methyl). Certain compounds in accordance with formula V, obtainable by the above process, are themselves novel and form a further aspect of the invention. Specifically, in this aspect the invention provides a compound of formula V or a pharmaceutically acceptable salt thereof wherein:
Ar represents 4-trifluoromethylphenyl, R3 represents 3-methylbutyl, Rlb represents isopropyl and Ar' represents 4-pyridyl; or wherein Ar represents 4-trifluoromethylphenyl, R3 represents 3-methylbutyl, Rlb represents methyl and Ar' represents 4-(trifluoromethyl)phenyl, 2,4-difluorophenyl, 4-chlorophenyl, 4- (trifluoromethoxy)phenyl, 2,4-dichlorophenyl, 2-(trifluoromethyl)phenyl, 3,4-dichlorophenyl, 2,3- dichlorophenyl, 2,5-difluorophenyl, 2,5-dichlorophenyl, 5-indolyl, 6-quinolyl, 7-thiophenyl, 5-pyrimidinyl or 4-pyrazolyl. These and other compounds in accordance with formula V may be used in the same manner and for the same therapeutic purposes as the compounds of formula I as described herein.
Specific examples of compounds in accordance with formula I are provided in the Examples appended hereto.
Compounds of formula I in which X represents CH and R1 represents CF3, alkyl, alkenyl, cycloalkyl or heterocyclyl may be obtained by reaction of an imine (1) with a nitro-olefin (2):
Figure imgf000009_0003
(1) (2) wherein V, Ar, Y, p, R2, R3, R6 and R1 have the same meanings as before. The reaction takes place in toluene solution, eg at reflux or by heating in a microwave apparatus.
Imines of formula (1) are conveniently generated in situ by reaction of an amine (3) with a cyclohexanone of formula (4):
Figure imgf000010_0001
where V, Ar, R3, Y, p, R2 and R6 have the same meanings as before. The reaction can be carried out in toluene with azeotropic removal of water.
Amines (3) may be obtained by treating ketones Ar-CO-R3 with hydroxylamine and hydrogenating the resulting oximes over Raney nickel. Alternatively, ketones Ar-CO-R3 may be condensed with α- methylbenzylamine and the resulting imines reduced (using NaBH4) to provide bis(benzylamines) ArCH(R3)-NH-CH(CH3)Ph, from which the desired amines (3) are obtained by hydrogenation over Pd/C. Use of a chiral α-methylbenzylamine facilitates isolation of amines (3) as single enantiomers, enabling control of the stereochemistry at one of the chiral centres in formula I.
Compounds of formula I in which X represents CRla and R1 is CF3, alkyl, alkenyl, cycloalkyl or heterocyclyl may be obtained by reaction of an amine (3) with a 1,4-dicarbonyl compound (5):
Figure imgf000010_0002
(5)
The reaction takes place in toluene solution in the presence of an acid catalyst (eg. acetic acid) with azeotropic removal of water. Alternatively, the reaction can be carried out in dichloromethane at -780C in the presence of triethylamine and TiCl4.
Compounds (5) are available by reaction of an enamine (6):
Figure imgf000011_0001
(6)
with a halo-ketone R^-CO-CH^R^-Hal where Hal is chloride or bromide. The reaction takes place in DMF at ambient temperature and is particularly suitable when R1 is H or alkyl.
Enamines (6) are formed from ketones (4) by refluxing with pyrrolidine in toluene solution using an acid catalyst such as acetic acid with azeotropic removal of water.
A preferred route to dicarbonyl compounds (5) comprises oxidative cleavage of olefins (7):
Figure imgf000011_0002
where V, Y, p, R1, Rla, R2 and R6 have the same meanings as before. The cleavage may be effected by ozonolysis in methanol/dichloromethane, or alternatively by treatment with RuCl3 and NaIO4. Ozonolysis is preferred when Rla is H.
Olefins (7) may be obtained by treatment of ketones (4) with triethylorthoformate, and reaction of the resulting diethyl ketals with an allylic alcohol (8):
Figure imgf000011_0003
where R1 and Rla have the same meanings as before. The reaction may be carried out at about 1250C in the presence of propionic acid. The initial product is an enol ether which undergoes Claisen rearrangement to provide the olefin (7).
Compounds of formula I in which X is N may be obtained by reaction of diketones (9) with hydrazines (10):
Figure imgf000012_0001
(9) (10)
The reaction takes place in refluxing ethanol. Diketones (9) are available by reaction of enamines (6) with R1 -COCl. Hydrazines (10) are available by reaction of Ar-CH(R3)-Br with hydrazine hydrate in isopropanol at 7O0C (see also EP 0234708).
A preferred route to compounds of formula IV comprises N-alkylation of tetrahydroindazoles (11) with Ar-CH(R3)-Hal, followed by oxidation of the allyl group to the corresponding carboxylic acid:
Figure imgf000012_0002
(11) (12) where Hal is Cl, Br or I and R11, R3 and Ar have the same meanings as before. The alkylation takes place at ambient temperature in DMF in the presence of sodium hydride. The oxidation may be carried out using excess sodium periodate in the presence OfRuCl3 hydrate as catalyst in a CCLt/MeCN/H2O mixture. Compounds (11) are obtainable by treating diketones (12) with hydrazine (e.g. in ethanol at ambient temperature). Diketones (12) are obtainable by reaction of 2-allylcyclohexanone with R11CO-Bt where Bt refers to benzotriazol-1-yl. The reaction takes place at -7O0C to ambient temperature in THF in the presence of strong base such as lithium hexamethyldisilazide.
Compounds of formula I in which R1 is halogen, CN or R4CO may be obtained by reaction of the corresponding compounds in which R1 is H with, respectively, an N-halosuccinimide, chlorosulfonyl isocyanate or R4COCl. The reaction with N-bromo- or N-chlorosuccinimide may be carried out at -780C in THF, and the reaction with N-iodosuccinimide at -2O0C in THF. The reaction with chlorosulfonyl isocyanate may be carried out at -780C in DMF/acetonitrile mixture, and the reaction with R4COCl may be carried out in dichloromethane in the presence OfAlCl3 at ambient temperature. The compounds of formula I in which R1 is H are obtainable by analogous routes to those described above in which R1 is alkyl, alkenyl, cycloalkyl or heterocyclyl. Compounds of formula I in which R1 is CH2N(R4)2 may be obtained by treatment of the corresponding compounds in which R1 is H with POCl3 and DMF in toluene at about 7O0C, and reaction of the resulting aldehydes with (R4)2NH2 and sodium triacetoxyborohydride, e.g. in chloroform at room temperature.
During all of the chemical processes described above, a carboxylic acid group represented by Y is preferably protected as the methyl ester or ethyl ester, the free acid being regenerated by hydrolysis in a final step, e.g. using LiOH in aqueous THF or dioxan.
Where they are not commercially available, the starting materials used in the schemes outlined above may be obtained by published routes or simple adaptations thereof. Suitable methods are described in the Examples section herein.
Since the compounds of Formula I have at least one asymmetric centre, they accordingly exist in enantiomeric forms. If desired, the individual enantiomers may be isolated in pure form by conventional means. For example, a racemic mixture may be resolved into its component enantiomers by preparative chiral HPLC, or by treatment with an optically pure amine to form diastereomeric salt pairs, separable by fractional crystallisation, from which the optically pure acids may be regenerated. Similarly, a racemic acid may be reacted with an optically pure alcohol or amine to form pairs of diastereomeric esters or amides which may be separated by chromatography or fractional crystallisation and hydrolysed to yield enantiomerically-pure acids. These resolution techniques may equally well be practised on the synthetic precursors of the compounds of Formula I, and the resulting optically-pure intermediates used to prepare compounds of Formula I in optically-pure form.
The invention further provides a pharmaceutical composition comprising compound of formula I or pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier.
Preferably these compositions are in unit dosage forms such as tablets, pills, capsules, powders, granules, sterile parenteral solutions or suspensions, metered aerosol or liquid sprays, drops, ampoules, transdermal patches, auto-injector devices or suppositories; for oral, parenteral, intranasal, sublingual or rectal administration, or for administration by inhalation or insufflation. The principal active ingredient typically is mixed with a pharmaceutical carrier, e.g. conventional tableting ingredients such as corn starch, lactose, sucrose, sorbitol, talc, stearic acid, magnesium stearate and dicalcium phosphate, or gums, dispersing agents, suspending agents or surfactants such as sorbitan monooleate and polyethylene glycol, and other pharmaceutical diluents, e.g. water, to form a homogeneous preformulation composition containing a compound of the present invention, or a pharmaceutically acceptable salt thereof. When referring to these preformulation compositions as homogeneous, it is meant that the active ingredient is dispersed evenly throughout the composition so that the composition may be readily subdivided into equally effective unit dosage forms such as tablets, pills and capsules. This preformulation composition is then subdivided into unit dosage forms of the type described above containing from 0.1 to about 500 mg of the active ingredient of the present invention. Typical unit dosage forms contain from 1 to 100 mg, for example 1, 2, 5, 10, 25, 50 or 100 mg, of the active ingredient. Tablets or pills of the composition can be coated or otherwise compounded to provide a dosage form affording the advantage of prolonged action. For example, the tablet or pill can comprise an inner dosage and an outer dosage component, the latter being in the form of an envelope over the former. The two components can be separated by an enteric layer which serves to resist disintegration in the stomach and permits the inner component to pass intact into the duodenum or to be delayed in release. A variety of materials can be used for such enteric layers or coatings, such materials including a number of polymeric acids and mixtures of polymeric acids with such materials as shellac, cetyl alcohol and cellulose acetate. The liquid forms in which the compositions useful in the present invention may be incorporated for administration orally or by injection include aqueous solutions, liquid- or gel-filled capsules, suitably flavoured syrups, aqueous or oil suspensions, and flavoured emulsions with edible oils such as cottonseed oil, sesame oil, coconut oil or peanut oil, as well as elixirs and similar pharmaceutical vehicles. Suitable dispersing or suspending agents for aqueous suspensions include synthetic and natural gums such as tragacanth, acacia, alginate, dextran, sodium carboxymethylcellulose, methylcellulose, poly(ethylene glycol), poly(vinylpyrrolidone) or gelatin.
The invention also provides a compound of formula I or a pharmaceutically acceptable salt thereof for use in therapy, in particular for use in treatment or prevention of a disease associated with deposition of
Aβ in the brain. The invention further provides the use of a compound of formula I or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for treatment or prevention of a disease associated with deposition of Aβ in the brain.
The disease associated with deposition of Aβ in the brain is typically Alzheimer's disease (AD), cerebral amyloid angiopathy, multi-infarct dementia, dementia pugilistica or Down syndrome, preferably AD.
In another aspect, the invention provides the use of a compound of Formula I as defined above, or a pharmaceutically acceptable salt thereof, in the manufacture of a medicament for treating, preventing or delaying the onset of dementia associated with Alzheimer's disease, cerebral amyloid angiopathy,
HCHWA-D, multi-infarct dementia, dementia pugilistica or Down syndrome. The invention also provides a method of treating or preventing a disease associated with deposition of Aβ in the brain comprising administering to a patient in need thereof a therapeutically effective amount of a compound of Formula I as defined above or a pharmaceutically acceptable salt thereof.
In a further aspect, the invention provides a method of treating, preventing or delaying the onset of dementia associated with Alzheimer's disease, cerebral amyloid angiopathy, HCHWA-D, multi-infarct dementia, dementia pugilistica or Down syndrome comprising administering to a patient in need thereof a therapeutically effective amount of a compound of Formula I as defined above or a pharmaceutically acceptable salt thereof.
The compounds of Formula I modulate the action of γ-secretase so as to selectively attenuate production of the (1-42) isoform of Aβ without significantly lowering production of the shorter chain isoforms such as Aβ(l-40). This results in secretion of Aβ which has less tendency to self-aggregate and form insoluble deposits, is more easily cleared from the brain, and/or is less neurotoxic. Therefore, a further aspect of the invention provides a method for retarding, arresting or preventing the accumulation of Aβ in the brain comprising administering to a subject in need thereof a therapeutically effective amount of a compound of Formula I as defined above or a pharmaceutically acceptable salt thereof.
Because the compounds of formula I modulate the activity of γ-secretase, as opposed to suppressing said activity, it is believed that the therapeutic benefits described above will be obtained with a reduced risk of side effects, e.g. those that might arise from a disruption of other signalling pathways (e.g. Notch) which are also controlled by γ-secretase.
In one embodiment of the invention, the compound of Formula I is administered to a patient suffering from AD, cerebral amyloid angiopathy, HCHWA-D, multi-infarct dementia, dementia pugilistica or Down syndrome, preferably AD. In an alternative embodiment of the invention, the compound of Formula I is administered to a patient suffering from mild cognitive impairment or age-related cognitive decline. A favourable outcome of such treatment is prevention or delay of the onset of AD. Age-related cognitive decline and mild cognitive impairment (MCI) are conditions in which a memory deficit is present, but other diagnostic criteria for dementia are absent (Santacruz and Swagerty, American Family Physician, 63 (2001), 703-13). (See also "The ICD-10 Classification of Mental and Behavioural Disorders", Geneva: World Health Organisation, 1992, 64-5). As used herein, "age-related cognitive decline" implies a decline of at least six months' duration in at least one of: memory and learning; attention and concentration; thinking; language; and visuospatial functioning and a score of more than one standard deviation below the norm on standardized neuropsychologic testing such as the MMSE. In particular, there may be a progressive decline in memory. In the more severe condition MCI, the degree of memory impairment is outside the range considered normal for the age of the patient but AD is not present. The differential diagnosis of MCI and mild AD is described by Petersen et ah, Arch. Neurol, 56 (1999), 303-8. Further information on the differential diagnosis of MCI is provided by Knopman et al, Mayo Clinic Proceedings, 78 (2003), 1290-1308. In a study of elderly subjects, Tuokko et al (Arch, Neurol., 60 (2003) 577-82) found that those exhibiting MCI at the outset had a three-fold increased risk of developing dementia within 5 years.
Grundman et al (J. MoI. Neurosci., 19 (2002), 23-28) report that lower baseline hippocampal volume in MCI patients is a prognostic indicator for subsequent AD. Similarly, Andreasen et al (Acta Neurol. Scand, 107 (2003) 47-51) report that high CSF levels of total tau, high CSF levels of phospho-tau and lowered CSF levels of Aβ42 are all associated with increased risk of progression from MCI to AD. Within this embodiment, the compound of Formula I is advantageously administered to patients who suffer impaired memory function but do not exhibit symptoms of dementia. Such impairment of memory function typically is not attributable to systemic or cerebral disease, such as stroke or metabolic disorders caused by pituitary dysfunction. Such patients may be in particular people aged 55 or over, especially people aged 60 or over, and preferably people aged 65 or over. Such patients may have normal patterns and levels of growth hormone secretion for their age. However, such patients may possess one or more additional risk factors for developing Alzheimer's disease. Such factors include a family history of the disease; a genetic predisposition to the disease; elevated serum cholesterol; and adult-onset diabetes mellitus. In a particular embodiment of the invention, the compound of Formula I is administered to a patient suffering from age-related cognitive decline or MCI who additionally possesses one or more risk factors for developing AD selected from: a family history of the disease; a genetic predisposition to the disease; elevated serum cholesterol; adult-onset diabetes mellitus; elevated baseline hippocampal volume; elevated CSF levels of total tau; elevated CSF levels of phospho-tau; and lowered CSF levels of Aβ(l-42). A genetic predisposition (especially towards early onset AD) can arise from point mutations in one or more of a number of genes, including the APP, presenilin-1 and presenilin-2 genes. Also, subjects who are homozygous for the ε4 isoform of the apolipoprotein E gene are at greater risk of developing AD. The patient's degree of cognitive decline or impairment is advantageously assessed at regular intervals before, during and/or after a course of treatment in accordance with the invention, so that changes therein may be detected, e.g. the slowing or halting of cognitive decline. A variety of neuropsychological tests are known in the art for this purpose, such as the Mini-Mental State Examination (MMSE) with norms adjusted for age and education (Folstein et al, J. Psych. Res., 12 (1975), 196-198, Anthony et al, Psychological Med., 12 (1982), 397-408; Cockrell et al, Psychopharmacology, 24 (1988), 689-692; Crum et al, J. Am. Med. Assoc'n. 18 (1993), 2386-2391). The MMSE is a brief, quantitative measure of cognitive status in adults. It can be used to screen for cognitive decline or impairment, to estimate the severity of cognitive decline or impairment at a given point in time, to follow the course of cognitive changes in an individual over time, and to document an individual's response to treatment. Another suitable test is the Alzheimer Disease Assessment Scale (ADAS), in particular the cognitive element thereof (ADAS-cog) (See Rosen et al, Am. J. Psychiatry, 141 (1984), 1356-64).
For treating or preventing Alzheimer's disease, a suitable dosage level is about 0.01 to 250 mg/kg per day, preferably about 0.01 to 100 mg/kg per day, and more preferably about 0.05 to 50 mg/kg of body weight per day, of the active compound. The compounds may be administered on a regimen of 1 to 4 times per day. In some cases, however, a dosage outside these limits may be used. The compounds of Formula I optionally may be administered in combination with one or more additional compounds known to be useful in the treatment or prevention of AD or the symptoms thereof. Such additional compounds thus include cognition-enhancing drugs such as acetylcholinesterase inhibitors (e.g. donepezil and galanthamine), NMDA antagonists (e.g. memantine) or PDE4 inhibitors (e.g. Ariflo™ and the classes of compounds disclosed in WO 03/018579, WO 01/46151, WO 02/074726 and WO 02/098878). Such additional compounds also include cholesterol-lowering drugs such as the statins, e.g. simvastatin. Such additional compounds similarly include compounds known to modify the production or processing of Aβ in the brain ("amyloid modifiers"), such as compounds which inhibit the secretion of Aβ (including γ-secretase inhibitors, β-secretase inhibitors, and GSK-3α inhibitors), compounds which inhibit the aggregation of Aβ, and antibodies which selectively bind to Aβ. Such additional compounds further include growth hormone secretagogues, e.g. as described in WO 2004/110443 and WO 2004/080459.
In this embodiment of the invention, the amyloid modifier may be a compound which inhibits the secretion of Aβ, for example an inhibitor of γ-secretase (such as those disclosed in WO 01/53255, WO 01/66564, WO 01/70677, WO 01/90084, WO 01/77144, WO 02/30912, WO 02/36555, WO 02/081435, WO 02/081433, WO 03/018543, WO 03/013506, WO 03/013527, WO 03/014075, WO 03/093251, WO 03/093252, WO 03/093253, WO 03/093264, WO 2004/031137, WO 2004/031138, WO 2004/031139, WO 2004/039370, WO 2004/039800, WO 2004/101538, WO 2004/101539 and WO 2005/030731), or a β-secretase inhibitor (such as those disclosed in WO 03/037325, WO 03/030886, WO 03/006013, WO 03/006021, WO 03/006423, WO 03/006453, WO 02/002122, WO 01/70672, WO 02/02505, WO
02/02506, WO 02/02512, WO 02/02520, WO 02/098849 and WO 02/100820), or any other compound which inhibits the formation or release of Aβ including those discled in WO 98/28268, WO 02/47671 , WO 99/67221, WO 01/34639, WO 01/34571, WO 00/07995, WO 00/38618, WO 01/92235, WO 01/77086, WO 01/74784, WO 01/74796, WO 01/74783, WO 01/60826, WO 01/19797, WO 01/27108, WO 01/27091, WO 00/50391, WO 02/057252, US 2002/0025955 and US2002/0022621.
Alternatively, the amyloid modifier may be a compound which inhibits the aggregation of Aβ or otherwise attenuates is neurotoxicicity. Suitable examples include chelating agents such as clioquinol (Gouras and Beal, Neuron, 30 (2001), 641-2) and the compounds disclosed in WO 99/16741, in particular that known as DP-109 (Kalendarev et al, J. Pharm. Biomed. Anal, 24 (2001), 967-75). Other inhibitors of Aβ aggregation suitable for use in the invention include the compounds disclosed in WO 96/28471, WO 98/08868 and WO 00/052048, including the compound known as Apan™ (Praecis); WO 00/064420, WO 03/017994, WO 99/59571 (in particular 3-aminopropane-l -sulfonic acid, also known as tramiprosate or Alzhemed™); WO 00/149281 and the compositions known as PTI-777 and PTI-00703 (ProteoTech); WO 96/39834, WO 01/83425, WO 01/55093, WO 00/76988, WO 00/76987, WO 00/76969, WO 00/76489, WO 97/26919, WO 97/16194, and WO 97/16191. Further examples include phytic acid derivatives as disclosed in US 4,847,082 and inositol derivatives as taught in US 2004/0204387.
Alternatively, the amyloid modifier may be an antibody which binds selectively to Aβ. Said antibody may be polyclonal or monoclonal, but is preferably monoclonal, and is preferably human or humanized. Preferably, the antibody is capable of sequestering soluble Aβ from biological fluids, as described in WO 03/016466, WO 03/016467, WO 03/015691 and WO 01/62801. Suitable antibodies include humanized antibody 266 (described in WO 01/62801) and the modified version thereof described in WO 03/016466. Suitable antibodies also include those specific to Aβ-derived diffusible ligands (ADDLS), as disclosed in WO 2004/031400.
As used herein, the expression "in combination with" requires that therapeutically effective amounts of both the compound of Formula I and the additional compound are administered to the subject, but places no restriction on the manner in which this is achieved. Thus, the two species may be combined in a single dosage form for simultaneous administration to the subject, or may be provided in separate dosage forms for simultaneous or sequential administration to the subject. Sequential administration may be close in time or remote in time, e.g. one species administered in the morning and the other in the evening. The separate species may be administered at the same frequency or at different frequencies, e.g. one species once a day and the other two or more times a day. The separate species may be administered by the same route or by different routes, e.g. one species orally and the other parenterally, although oral administration of both species is preferred, where possible. When the additional compound is an antibody, it will typically be administered parenterally and separately from the compound of Formula I.
The ability of the compounds of Formula I to selectively inhibit production of Aβ(l-42) was determined using the following assay:
Cell-based γ-Secretase Assay
Human SH-SY5Y neuroblastoma cells overexpressing the direct γ-secretase substrate SPA4CT were induced with sodium butyrate (10 mM) for 4 hours prior to plating. Cells were plated at 35,000 cells/well/100 μl in 96-well plates in phenol red-free MEM/10% FBS, 50 mM HEPES, 1% Glutamine and incubated for 2 hrs at 37 0C, 5% CO2.
Compounds for testing were diluted into Me2SO to give a ten point dose-response curve. Typically 10 μl of these diluted compounds in Me2SO were further diluted into 182 μl dilution buffer (phenol red-free MEM/10% FBS, 50 mM HEPES, 1% Glutamine) and 10 μl of each dilution was added to the cells in 96- well plates (yielding a final Me2SO concentration of 0.5%). Appropriate vehicle and inhibitor controls were used to determine the window of the assay.
After incubation overnight at 37 0C, 5%CO2, 10 μl and 50 μl media were transferred into a fresh Costar round-bottom 96-well plate for detection of Aβ(40) and Aβ(42) peptides, respectively. 40 μl Origen buffer (PBS, 2% BSA, 0.2% Tween-20) was added to the Aβ(40) wells followed by the addition of 25 μl the respective antibody premixes to the wells:
Aβ(40) premix: 1 μg/ml ruthenylated G2-10 antibody, 4 μg/ml biotinylated 4G8 antibody diluted in Origen buffer
Aβ(42) premix: 0.5 μg/ml ruthenylated G2-11 antibody, 4 μg/ml biotinylated 4G8 antibody diluted in Origen buffer
(Biotinylated 4G8 antibody supplied by Signet Pathology Ltd; G2-10 and G2-11 antibodies supplied by Chemicon) After overnight incubation of the assay plates on a shaker at 4 0C, the Origen M8 Analyser (Igen
Inc.) was calibrated according to the manufacturer's instructions. 25 μl of streptavidin magnetic bead (Dynal) premix (400 μg/ml streptavidin beads/ml in Origen buffer) was added to the assay plates and incubated on a shaker for 15 minutes. 150 μl Origen buffer was added to each well and the plates were read on the Origen M8 Analyser according to the manufacturer's instructions. Cell viability was measured in the corresponding cells after removal of the media for the Aβ assays by a colorimetric cell proliferation assay (CellTiter 96™ AQ assay, Promega) utilizing the bioreduction of MTS (Owen's reagent) to formazan according to the manufacturer's instructions. Briefly, 5 μl of 10x MTS/PES was added to the remaining 50 μl of media before returning to the incubator. The optical density was read at 495 nm after ~4 hours.
LD50 and IC50 values for inhibition of Aβ(40) and Aβ(42) were calculated by nonlinear regression fit analysis using the appropriate software (eg. Excel fit). The total signal and the background were defined by the corresponding Me2SO and inhibitor controls.
The compounds of the invention give IC50 values for Aβ(l-42) inhibition that are at least 2-fold lower than the corresponding IC50 values for Aβ(l-40) inhibition, typically at least 5-fold lower, and in the preferred cases at least 50-fold lower.
EXAMPLES Intermediate 1
Figure imgf000019_0001
Step 1
Magnesium (17 g) was stirred 10 min under nitrogen then THF (400 mL) was added. l-Bromo-4- methylbutane (5 mL) was added and the mixture stirred 5 min until the reaction initiated (exotherm) the reminder of the bromomethylbutane (100 g, 0.672 mol) was added keeping the temp below 350C (water bath). The mixture was stirred 1 hr at RT and a solution of 4-trifluoromethylbenzonitrile (100 g, 0.584 mol) in toluene (1 L) containing some CuBr was added dropwise keeping the temp 250C. The solution was stirred 1 h and quenched carefully with 15% H2SO4 (exotherm). The organic layer was decanted, washed with brine, dried over (MgSO4) and concentrated in vacuo. The oil was purified by column chromatography on silica using isohexane as eluant to give 4-methyl-l-[4-(trifluoromethyl)phenyl]pentan- 1-one (126 g) which solidified on standing. 1H NMR δ (ppm)(CDCl3): 8.06 (2H, d, J8.1 Hz), 7.73 (2H, d, J8.1 Hz), 2.99 (2H, app. t, J7.4 Hz), 1.68-1.60 (3H, m), 0.96 (6H, d, J6.3 Hz). Step 2
To a solution of 4-methyl-l-[4-(trifluoromethyl)phenyl]pentan-l-one [Stepl] (70 g, 0.312 mol) in toluene (500 mL) at RT was added 5-phenylethylamine (44.5 g, 0.374 mol) and zinc chloride (2 g, 15.61 mmol). A Dean-Stark apparatus was attached and the reaction refluxed for 16 h. The reaction was cooled, washed with IN NaOH (800 mL), saturated ammonium chloride (x3), dried (MgSO4) and evaporated to give 4- methyl-l-[4-(trifluoromethyl)phenyl]pentylidene}[(liS)-l-phenylethyl]amine (87 g) as a 3:1 mixture of isomers as an oil that was taken directly into Step 3. Step 3
To a solution of {4-methyl-l-[4-(trifluoromethyl)phenyl]pentylidene}[(liS)-l-phenylethyl]amine [Step 2] (87 g, 0.25 mol) in methanol (0.5 L) at -20 0C was added sodium borohydride (10 g, 0.263 mol) portionwise. The solution was stirred 1/2 hrs at O0C and quenched carefully with IN HCl , basifϊed with 4N NaOH and extracted with EtOAc. The organic layer was decanted, dried (MgSO4) and evaporated to give 85 g of {4-methyl-l-[4-(trifluoromethyl)phenyl]pentyl}[(liS)-l-phenylethyl]amine as a 3:1 mixture of diastereomers by NMR. This was dissolved in methanol (250 mL) and phthalic acid (4Og) was added. The solution was stirred at RT when it started to crystallise. The mixture was stirred 2 h at RT and the solid was then filtered to give single diastereomer {(15)-4-methyl-l-[4-(trifluoromethyl)phenyl]pentyl} [(1S)-I- phenylethyl] amine as the phthalic acid salt (70.5 g). A small portion of the phthalic acid salt was partitioned between CDCl3 and aqueous K2CO3 to form the free base and a 1H NMR was taken; 1H NMR δ (ppm)(CDCl3): 7.57 (2H, d, J8.0 Hz), 7.33 (5H, dd, J7.6, 9.8 Hz), 7.16 (2H, d, J6.9 Hz), 3.40 (IH, q, J 6.7 Hz), 3.32 (lH, t, J6.9 Hz), 1.66-1.48 (2H, m), 1.46-1.32 (IH, m), 1.26 (3H, d, J 6.7 Hz), 1.19-1.09 (IH, m), 0.95-0.85 (IH, m), 0.79 (3H, d, J3.6 Hz), 0.77 (3H, d, J3.5 Hz). Step 4
A suspension of {(liS)-4-methyl-l-[4-(trifluoromethyl)phenyl]pentyl}[(liS)-l-phenylethyl] amine phthalate salt [Step 3] (70 g, 0.135 mol) and 10% palladium on carbon (900 mg) in EtOH (300 mL) was hydrogenated under 40psi at 570C for 3.5 h. The catalyst was removed by filteration and the fitrate concentrated to a half, diluted with ethyl acetate, washed three times with 4N NaOH then with brine, dried (MgSO4) and evaporated to give the title compound as a liquid (60 g); 1H NMR δ (ppm)(CDCl3): 7.58 (2H, d, J8.2 Hz), 7.43 (2H, d, J8.0 Hz), 3.93 (IH, t, J6.8 Hz), 1.69-1.59 (2H, m), 1.57-1.49 (IH, m), 1.28-1.18 (IH, m), 1.11-1.01 (IH, m), 0.87 (3 H, d, J 1.8 Hz), 0.85 (3 H, d, J 1.8 Hz); mlz (ES+) 246 (M+H+); OCD 20 = -9.0 (c = 1, CHCl3).
Intermediate 2
(lJ?)-4-Methyl-l-[4-(trifluoromethyl)phenyl]pentyl amine
Figure imgf000020_0001
The enantiomer (+)-{(lJ?)-4-methyl-l-[4-(trifluoromethyl)phenyl]pentyl amine was prepared as Intermediate 1 employing i?-phenylethylamine instead of 5-phenylethyl amine in Step 2. Tntcrmcdiatc 3
Figure imgf000021_0001
Step 1
Figure imgf000021_0002
2-Methylprop-2-en-l-ol (57 g, 0.79 mol) and 1,1-diethoxycyclohexane (190 g, 1.1 mol) and propionic acid (10 mL) were heated to 17O0C for 16 h under reflux. The mixture was cooled, a Dean-Stark trap was fitted, and the mixture reheated to 17O0C. The volatile material (mainly ethanol) was removed using the trap, and heating was continued for a further 30h, prior to cooling to room temperature. The resulting oil was purified by distillation (bp 76-80 0C /50 mbar). Colourless oil (104.5 g, 87%). 1H NMR δ (ppm)(CDCl3): 4.76 (IH, s), 4.66 (IH, s), 2.25-2.50 (5H, m), 2.0-2.15 (2H, m), 1.4-1.8 (5H, m), 1.25- 1.35 (2H, m). Step 2
Figure imgf000021_0003
Prepared by alkylation of the product of Step 1 with ethyl bromoacetate in THF at -780C in the presence of KHMDS using the procedure described in Example 12 Step 2.
Figure imgf000021_0004
To a vigorously stirred suspension of ethyl [3-(2-methylprop-2-en-l-yl)-2-oxocyclohexyl]acetate [Step 2] (25 g, 105 mmol) and sodium periodate (89.8 g, 420 mmol) in CCl4 (50 mL) / MeCN (50 mL) and water (75 mL) was added ruthenium trichloride monohydrate (0.44 g, 2.1 mmol), and stirring was continued for 16 h. The resulting mixture was partitioned between water (850 mL) and DCM (850 mL), and the aqueous layer/solid residue was extracted with DCM (x2). The combined organic phases were washed (brine), dried (sodium sulphate) and concentrated to give a dark-brown oil, which was purified by flash chromatography (Biotage SPl, 65M, 10-40% EtOAc/isohexane) gave the mixture of diastereoisomers as a pale yellow oil (11 g, 43%) 1H NMR δ (ppm)(CDCl3): 4.09-4.15 (2 H, m), 2.65-3.05 (4H, m), 2.35-2.45 (IH, m), 2.05-2.2 (4H, m), 1.6-2.0 (5H, m) 1.3-1.45 (IH, m), 1.25-1.3 (3H, m). Step 4
The product of Step 3 (2.0 g, 8.33 mmol), Intermediate 2 (2.04 g, 8.33 mmol) and 4-methyϊbenzenesulfonic acid hydrate (0.16 g, 0.83 mmol) were dissolved in toluene (7 mL) and heated to 15O0C for 48 h with a Dean-Stark trap. The mixture was cooled, and partitioned between DCM and NaHCO3(aq). The organic phase was dried (sodium sulfate), and concentrated under reduced pressure to give a dark brown oil, which was purified by flash chromatography (Biotage SPl, 4OM, 0->15% EtOAc/ isohexane) to give a pale yellow oil. Mixture of diastereoisomers 1H NMR (360 MHz), δ (ppm)(CDCl3): 7.54 (2H, t), 7.14 (IH, d), 7.03 (IH, d), 5.71 (IH, d), 5.23-5.17 (IH, m), 4.14-3.99 (2H, m), 3.28-2.94 (IH, m) 2.50-0.83 (25H, m).
Intermediate 4
Mixture of ethyl (2-ethoxycyclohex-2-en-l-yl)acetate and ethyl (2,2-diethoxycyclohexyl)acetate
Figure imgf000022_0001
To a stirred solution of ethyl (2-oxocyclohexyl)acetate (40.2 mL, 0.228 mol) in ethanol (66 mL) was added /?-toluenesulfonic acid (422 mg, 2.28 mmol) and triethyl orthoformate (113 mL, 0.684 mol). The reaction mixture was heated to 95 0C and stirred for 16 h. The mixture was concentrated in vacuo at 6O0C for 2 1/2 hours to remove excess triethyl orthoformate. The mixture was used crude in subsequent reactions. 1H NMR δ (ppm)(CDCl3): 4.60 (IH, t, J3.9 Hz), 4.17-4.09 (4H, m), 3.76-3.58 (4H, m), 3.47-3.41 (3H, m), 3.11 (IH, s), 2.71-2.63 (2H, m), 2.58-2.40 (IH, m), 2.37-2.09 (4H, m), 2.07-1.97 (4H, m), 1.91-1.33 (8H, m), 1.31-1.16 (14H, m).
Intermediate 5
1 -Bromo-4-methyl- 1 -(4-(trifluoromethyl)phenyl)pentane
Br jy t Sodium borohydride (2.8 g, 0.074 mol) was added portionwise to a solution of 4-methyl-l-[4-
(trifluoromethyl)phenyl]pentan-l-one [Intermediate 1; Step 1] in EtOH (50 mL) cooled in ice. When addition was complete (30 min) the mixture was stirred at RT for 1 h then quenched with NH4Cl solution (50 mL) followed by 2N HCl (20 mL). Extraction with ether (3x50 mL) followed by drying (MgSO4) and concentration of the organic phase gave 4-methyl-l-(4-(trifluoromethyl)phenyl)pentan-l-ol as a colourless oil.
PBr3 (5g, 0.018 mol) was added dropwise to a solution of this alcohol (5 g, 0.02 mol) stirring at RT. The mixture was stirred at RT for Ih and then poured into ice and the mixture extracted with Et2O (3x20 mL). The organic phase was dried (MgSO4) and concentrated to give the bromide as an oil. 1H NMR δ (ppm)(CDCl3): 7.6 (2H, d, J8 Hz), 7.49 (2H, d, J8 Hz), 4.90 (IH, t, J7 hz), 2.4-1.1 (5H, m), 0.89 (6H, d, J 7 Hz).
Intermediate 6
Figure imgf000023_0001
To a stirred solution of DMF (2.32 ml, 30.03 mmol) in dry toluene (10 ml) was added POCl3 (4.14 g, 27.03 mmol) dropwise. The resulting biphasic mixture was stirred at 700C for 5 min, prior to addition of Intermediate 2 as a solution in toluene (10ml). The resulting solution was stirred at this temperature for 2 h, and then poured onto saturated sodium acetate (aq). The aqueous phase was extracted with EtOAc, the combined organic phases were washed (brine), dried (sodium sulfate) and concentrated. Purification by flash chromatography (Biotage SPl, 25S, 2-30% EtOAc / isohexane) gave a colourless oil as a 1:1 mixture of diastereoisomers. IH NMR (360 MHz, CDC13): δ 9.91 (m, 1 H), 7.60 (t, 2 H), 7.16 (t, 2 H), 5.30 (m, 1 H), 4.13-3.99 (m, 2 H), 3.21 (d, 1 H), 2.95 (t, 1 H), 2.70-1.18 (m, 14 H), 0.98-0.90 (m, 8 H).
Intermediate 7
(liS)-3-Phenyl-l-[4-(trifluoromethyl)phenyl]propyl amine hydrochloride salt
Figure imgf000023_0002
2-methyl-N-{(15)-3-phenyl-l-[4-(trifluoromethyl)phenyl]propyl}propane-2-sulfinamide (JACS, 2005, 127, 1092-3) (8.3 g, 21.7 mmol) was dissolved in methanol (50 mL) and a 4M solution of HCl in dioxane (10.8 mL) was added. The solution was stirred at RT for 1 h then concentrated. The residue was triturated with isohexane to give a colourless solid which was collected by filtration. 1H ΝMR (400 MHz), δ (ppm)(DMSO-D6): 8.7 (3H, s), 7.85 (2H, d, J 8.3 Hz), 7.77 ((2H, d, J 8.3 Hz), 7.29-7.26 (2H, m), 7.20- 7.13 (3H, m), 4.36 (IH, m), 2.4-2.35 (2H, m), 2.35-2.25 (m, IH), 2.2-2.1 (IH, m).
Example 1
(3-Bromo-2-methyl- 1 - {(lJ?)-4-methyl- 1 -[4-(trifluoromethyl)phenyl]pentyl} -4,5,6,7-tetrahydro- lH-indol-7- yl)acetic acid
Figure imgf000024_0001
Step 1
To a stirred solution of Intermediate 3 (72 mg, 0.16 mmol) in dry THF (4ml) at -78 0C was added NBS (34 mg, 0.19 mmol) as a solid. The resulting mixture was stirred at this temperature for 2 h, and then quenched with NaHCO3(aq). The mixture was extracted with EtOAc (x2), the combined organic phases were dried (MgSO4), and purified by flash chromatography (Biotage SPl, 12M, 0->8% EtOAc/isohexane) to give a pale yellow oil. (70mg, 82%). Step 2 The product of Step 1 (25 mg, 0.05 mmol), was dissolved in EtOH (3 mL), and 0.5M NaOH(aq) (0.29 mL) was added. After stirring at RT for 2 h, the solvent was removed under reduced pressure, and the residue was partitioned between 2M HCl (aq)/DCM, filtered through a phase-separation cartridge and concentrated. Purification by flash chromatography (Biotage SPl, 25S, 20->75% EtOAc/isohexane) gave a white foam, (15 mg, 63%). Mixture of diastereoisomers 1H NMR (400 MHz), δ (ppm)(CDCl3): 7.56 (2H, t), 7.14 (1H, d), 7.02 (IH, t), 5.22-5.16 (IH, m), 3.18 (IH, d), 2.52-2.0 (9H, m), 1.55-1.86 (5H, m), 1.37-1.17 (2H, m), 0.99-0.85 (6H, m); (ES+) 500, 502 (M+H+).
Example 2
(3-Chloro-2-methyl- 1 - {(lJ?)-4-methyl- 1 -[4-(trifluoromethyl)phenyl]pentyl} -4,5,6,7-tetrahydro- lH-indol-7- yl)acetic acid
Figure imgf000024_0002
Prepared from Intermediate 3 and N-chlorosuccinimide using an analogous procedure to Example 1. 1H
NMR (500 MHz), δ (ppm)(CDC13): 7.56 (2H, t,), 7.14 (IH, d), 7.03 (IH, d), 5.20-5.14 (IH, m), 3.19 (IH, m), 2.57-2.33 (4H, m), 2.26-2.18 (IH, m), 2.14-2.01 (3H, s), 1.86-1.68 (6H, m), 1.38-1.19 (2H, m), 0.96-0.89 (6H, m); (ES+) 456, 458 (M+H+).
Example 3
(3-Benzoyl-2-methyl- 1 - {(lJ?)-4-methyl- 1 -[4-(trifluoromethyl)phenyl]pentyl} -4,5,6,7-tetrahydro- lH-indol-
7-yl)acetic acid
Figure imgf000025_0001
Step 1
To a stirred solution of Intermediate 3 (80 mg, 0.18 mmol) and benzoyl chloride (25 mg, 0.18 mmol) in
DCM (3 mL) was added aluminium trichloride (24 mg, 0.18 mmol). The resulting wine-red solution was stirred at RT for 18 h, and then quenched with NaHCO3(aq). The mixture was extracted with DCM, the combined organic phases were dried (sodium sulfate), concentrated under reduced pressure, and purified by flash chromatography (Biotage SPl, 12M 0->40% EtOAc/isohexane) to give a yellow oil (9 mg, 9%).
Step 2
Analogous procedure to Example 1, Step 2.
1H NMR (400 MHz), δ (ppm)(CDCl3): 7.68 (2H, d), 7.60 (2H, t), 7.51-7.39 (3H, m), 7.21-7.02 (2H, m), 5.30 (IH, m), 3.15-3.3 (IH, m), 2.56-1.36 (17H, m), 0.99-0.85 (6H, m); (ES+) 526 (M+H+).
Example 4
(3-Cyano-2-methyl- 1 - {(lJ?)-4-methyl- 1 -[4-(trifluoromethyl)phenyl]pentyl} -4,5,6,7-tetrahydro- lH-indol-7- yl)acetic acid
Figure imgf000025_0002
Step 1
To a stirred solution of the Intermediate 3 (72 mg, 0.16 mmol) in DMF (1 mL) at -780C was added chlorosulfonyl isocyanate (45 mg, 0.32 mmol) in acetonitrile (1 mL), and the resulting mixture was stirred at this temperature for 4 h, and then allowed to warm to RT over 4 h, and stirred for a further 16 h. The mixture was quenched with NaHCO3(aq), and extracted with DCM (x3), the combined organic phases were dried (sodium sulphate) and concentrated. Purification by flash chromatography (0->30%
EtOAc/isohexane) gave a foam (12 mg, 16%).
Step 2
Analagous procedure to Example 1, Step 2. 1H NMR (400 MHz), δ (ppm)(CDCl3): δ 7.60 (2H, t), 7.10 (2H, dd), 5.27-5.21 (IH, m), 3.17 (IH, m), 2.65 (IH, m), 2.56-2.36 (3H, m), 2.23-2.04 (5H, m), 1.86-1.67 (4H, m), 1.35-1.09 (4H, m), 0.97-0.83 (6H, m); (ES+) 447 (M+H+).
Example 5
(3-Cyclohexyl- 1 - {(lJ?)-4-methyl- 1 -[4-(trifluoromethyl)phenyl]pentyl} -4,5,6,7-tetrahydro- lH-indol-7- yl)acetic acid
Figure imgf000026_0001
Step 1 Sodium hydride, 60% dispersion in oil (13.9 g, 34.8 mmol) was added portionwise to dimethoxyethane (300 mL) with water cooling. Triethyl phosphonoacetate (69 mL, 34.8 mmol) was added slowly. The mixture was stirred for 90 minutes at RT. Cyclohexanecarboxaldehyde (15 g, 13.4 mmol) was added and the mixture was stirred at RT for 18 h. Water (200 mL) was added and the mixture was extracted with ether. The organic phase was washed with brine, dried over sodium sulphate and concentrated to dryness. The residue was purified by column chromatography (40:1 isohexane-ethyl acetate) to give an oil (19.8 g, 79 %).
1H NMR (400 MHz), δ (ppm)(CDCl3): 6.91 (IH, dd, J 6.7, 15.8), 5.76 (IH, dd, J 1.5, 15.8), 4.18 (2H, q, J 7.1), 2.16-2.10 (IH, m), 1.76 (4H, dd, J 3.0, 12.9), 1.69 (IH, d, J 1.3), 1.31-1.13 (8H, m). Step 2 DIBAH, IM in hexanes (268 mL, 26.8 mmol) was added dropwise to a stirred solution of the product of Step 1 (19.5 g, 10.7 mmol) in ether (25 mL) maintaining the temperature below -700C. The mixture was stirred at -78°C for 3 h and then quenched with methanol followed by sat. ammonium chloride solution. The mixture was allowed to warm to RT, diluted with ether and washed with 2M HCl. The organic phase was washed with water and then brine, dried over sodium sulphate and concentrated to give a colourless oil (12.3 g, 82 %). 1H NMR (400 MHz), δ (ppm)(CDCl3): 5.67-5.55 (2H, m), 4.08 (2H, m), 2.00-1.94 (IH, m), 1.70 (5H, m), 1.32-1.02 (6H, m). Step 3
A few drops of propionic acid were added to the product of Step 2 (2.5 g, 17.9 mmol) and Intermediate 4 (8.4 g). The mixture was stirred and heated at 1500C for 18 h then cooled to RT. The reaction mixture was purified directly by column chromatography (5->10% EtOAc/isohexane) to give an oil (703 mg, 13 %) as a mixture of diastereomers. Step 4 Nitrogen was bubbled into a stirred solution of the product of Step 3 (703 mg, 2.28 mmol) in DCM (40 mL) at -78°C for a few minutes. Oxygen was then bubbled into the mixture followed by ozone. A blue colour persisted after a few minutes. Oxygen was bubbled through the mixture until the blue colour disappeared followed by nitrogen. Dimethylsulphide (1.0 mL, 13.7 mmol) was added and the mixture was stirred at -78°C for 2 h and then allowed to warm to RT overnight. The mixture was concentrated to dryness. The residue was dissolved in EtOAc and washed with water and brine, dried over sodium sulphate and concentrated to dryness to afford the dicarbonyl compound as a complex mixture of diastereomeric ketals (774 mg). Step 5 A mixture of product from Step 4 (774 mg, 2.51 mmol), Intermediate 2 (739 mg, 3.01 mmol), lithium perchlorate (266 mg, 2.51 mmol) and acetic acid (0.4 ml) in toluene (25 ml) was stirred and heated under reflux in a flask equipped with a Dean-Stark apparatus for 20 h. After cooling to RT and dilution with EtOAc, the mixture was washed with sat. NaHCO3 solution and brine, dried over sodium sulphate and concentrated to dryness. The residue was purified by column chromatography (20: 1 isohexane:EtOAc) to give an oil as a 1 : 1 mixture of diastereomers (398 mg, 31%). m/z (ES+) 518 (M+H+). Step 6
A mixture of the product from Step 5 (398 mg, 0.768 mmol) and lithium hydroxide (184 mg, 7.68 mmol) in water (4 mL) and dioxane (30 mL) was stirred and heated under reflux for 18 h. After cooling to RT and acidification to pH 1 with IM hydrochloric acid, the mixture was extracted with EtOAc and the organic extract was washed with water and brine, dried over sodium sulphate and concentrated to dryness. The residue was purified by column chromatography (0.5% acetic acid in 40: 1 DCM:methanol) to give a pale brown foamy solid. The chromatographed material was separated into single diastereomers using preparative HPLC (HIRPB column 250 x 20 mm id, 85% MeCN and 15% TFA (0.1%) in water, 20 ml/min). The first eluted compound was designated diastereomer 1 (61 mg). 1H NMR (500 MHz), δ (ppm)(CDCl3): 7.49 (2H, d, J 8.2), 7.02 (2H, d, J8.1), 6.53 (IH, s), 4.95 (IH, dd, J6.2, 9.2), 2.93 (IH, m), 2.63-2.55 (2H, m), 2.49 (IH, m), 2.37-2.31 (2H, m), 2.17-2.09 (IH, m), 2.04-1.97 (IH, m), 1.93 (2H, m), 1.76-1.66 (8H, m), 1.40-1.30 (4H, m), 1.24-1.16 (3H, m), 0.88 (6H, t, J6.1). The second eluted compound was designated diastereomer 2 (60 mg). 1H NMR (500 MHz), δ (ppm)(CDCl3): 7.55 (2H, d, J 8.2), 7.25 (2H, d, J8.2), 6.50 (IH, s), 5.00 (IH, t, J7.6), 3.29 (IH, m), 2.53 (IH, m), 2.44-2.36 (2H, m), 2.24 (IH, dd, J 11.1, 15.7), 2.09-2.01 (2H, m), 1.95 (3H, m), 1.81-1.51 (7H, m), 1.43-1.07 (8H, m), 0.88 (6H, m).
Examples 6-9
Figure imgf000027_0001
Examples 6-9 were made in analogous fashion to Example 5 starting from the appropriate aldehyde.
Figure imgf000028_0003
Examples 10-11
Figure imgf000028_0001
Examples 10-11 were made in analogous fashion to Example 5 starting from the appropriate aldehyde and using Intermediate 1 in Step 5 in place of Intermediate 2.
Figure imgf000028_0004
Example 12
Figure imgf000028_0002
Stepl
3-(Tetrahydro-2H-pyran-4-yl)prop-2-en-l-ol (prepared by the method of Example 5 Steps 1 and 2 starting with tetrahydropyran-4-carboxaldehyde) (2.16 g, 15.2 mmol) and cyclohexanone diethyl ketal (3.66 g, 21.3 mmol) containing a few drops of propionic acid were stirred and heated at 1500C for 18 h. After cooling to RT, the mixture was purified by column chromatography (7: 1 -> 4: 1 isohexane:EtOAc to give an oil as a mixture of diastereomers; 1.17 g (35 %). Step 2
A solution of the product from Step 1 (1.17 g, 5.27 mmol) in TΗF (5 mL) was added slowly to a solution of KΗMDS, 0.5 M in hexanes (11.6 ml, 5.80 mmol) in TΗF (25 mL) at -78°C maintaining the temperature below -700C. The mixture was stirred at -78°C for 1. Ethyl bromoacetate (641 μL, 5.80 mmol) was added dropwise, ensuring the temperature remained below -700C. The mixture was stirred at -78°C for 2 hours and allowed to warm to RT whereupon it was quenched with saturated ammonium chloride solution. The mixture was extracted with ethyl acetate. The organic phase was washed with brine, dried over sodium sulphate and concentrated to dryness. The residue was purified by column chromatography (4: 1 isohexane:EtOAc) to give an oil 620 mg, (38 %) as a mixture of diastereomers. Step 3
The product of Step 2 was treated as in Example 5 Steps 4-6 to provide the title compound, m/z ES" (M- H+) 490.
Example 13 (3-Trifluoromethyl)- 1 - {(lJ?)-4-methyl- 1 -[4-(trifluoromethyl) phenyl]pentyl} -4,5,6,7-tetrahydro- lH-indol- 7-yl)acetic acid
Figure imgf000029_0001
Prepared by the method of Example 12 using 4,4,4-trifluorobut-2-en-l-ol in Step 1. m/z ES- (M-H+) 474.
Example 14
Figure imgf000029_0002
Step 1
Intermediate 4 was reacted with 2-isopropylprop-2-en-l-ol by the method of Example 5 Step 3 and the product oxidised with RuCl3/NaIO4 as described for Step 3 of Intermediate 3. Reaction of the resulting diketone with Intermediate 2 by the method of Example 5 Step 1 gave the ethyl ester of (2-isopropyl-l-
{(15)-4-methyl-l-[4-(trifluoromethyl) phenyl]pentyl}-4,5,6,7-tetrahydro-lH-indol-7-yl)acetic acid.
Step 2
To a stirred solution of the product of Step 1 (1.0 g, 2.1 mmol) in DMF (8 mL) at -780C was added chlorosulfonyl isocyanate (0.2 ml, 2.1 mmol) in acetonitrile (8 mL). The resulting mixture was stirred at this temperature for 4h, and then allowed to warm to room temperature over 4 h, and stirred for a further
16 h. The mixture was quenched with NaΗCO3(aq), and extracted with DCM (x3), the combined organic phases were dried (MgSO4) and concentrated. Purification by flash chromatography (0->30% EtOAc/isohexane) gave a foam (720 mg, 65%). Step 3
The product of Step 3 was hydrolysed as described in Example 1 Step 2. The product was purified by flash chromatography (SiO2, 9:1->2:1 isohexane:EtOAc) to give the product as a mixture of diastereoisomers. The diastereoisomers were separated using reverse-phase preparative HPLC. First eluted compound (diastereoisomer 1) 1H NMR δ (ppm)(CDCl3): 7.59 (2H, d, J 8.2 Hz), 7.14 (2H, br), 5.17 (IH, br), 3.29 (IH, m), 2.66-2.49 (5H, m), 2.10 (2H, m), 1.77-1.23 (13H, m), 0.99 (3H, d, J 6.5 Hz), 0.93 (3H, d, J 6.5 Hz).
Second eluted compound (diastereoisomer 2) 1H NMR δ (ppm)(CDCl3): 7.62 (2H, d, J 8.2 Hz), 7.22 (2H, d, J8.2 Hz), 5.20 (IH, m), 3.28 (IH, br), 2.71-2.49 (5H, m), 2.10 (2H, m), 1.77-1.23 (13H, m), 0.99 (3H, d, J 6.5 Hz), 0.93 (3H, d, J 6.5 Hz).
Example 15
Figure imgf000030_0001
To a stirred solution of the product of Example 14 Step 1 (500 mg, 1.1 mmol) in dry THF (10 ml) at -200C was added N-iodosuccinimide (242 mg, 1.1 mmol). Reaction was slowly allowed to warm to room temperature and stirred for 2 h. The reaction was then quenched with ΝaHCO3(aq) and then the product extracted with EtOAc (x3). The organics were washed with brine, dried (MgSO4), filtered and evaporated. The residue was hydrolysed by the procedure of Example 1, Step 2 and purified by flash chromatography (SiO2, 4: 1->1 : 1 isohexane:EtOAc) to give the product as a mixture of diastereoisomers. 1H NMR δ (ppm)(CDCl3): 7.57 (2H, m), 7.25 (IH, m), 7.07 (IH, m), 5.12 (IH, br), 3.21 (IH, m), 2.60- 0.85 (26H, m).
Example 16
(3-(l , 1 -Dimethylethyl)- 1 - { 1 -4-methyl- 1 -[4-(trifluoromethyl)phenyl]pentyl} -4,5,6,7-tetrahydro- lH-indazol- 7-yl)acetic acid
Figure imgf000030_0002
Step 1 : 7-Allyl-3-(l.l-dimethylethyl)-4.5.6.7-tetrahvdro-lH-indazole: A IM solution of lithium hexamethyldisilazide in THF (40 mL, 0.04 mol) was added dropwise to solution of 2-allylcylohexanone (5g, 0.036 mol) in dry THF (50 mL) cooled below -70° under N2. After Ih, a solution of l-(2,2,2-trimethylacetyl)-lH-benzotriazole (7.2 g, 0.036 mol) in dry THF (10 mL) was added in one portion and the mixture allowed to reach room temperature over 2h. After a further Ih, IN hydrochloric acid (50 mL) was added and the mixture extracted with ether (3x50 mL). The combined organic phase was washed with IN Na2CO3 solution (20 mL), brine (20 mL), dried (MgSO4) and concentrated to an oil. TLC silica (EtOAc:Hexane 10%) showed three products A, B and C (Rf, 0.6, 0.25 and 0.2 respectively. MPLC on silica eluting with EtOAc:Hexane 0->20% enabled isolation of 3g of A, an oil, 1.5 g of B and 0.7 g of C. NMR showed A to be the O-acylated material and B and C the desired diastereomeric products, cis- and tran^-2-allyl-6-(l-(2,2,2-trimethylacetyl))cyclohexan-l-one.
1H NMR δ (ppm)(CDCl3): A; 5.85-5.65 (IH, m), 5.35-5.3 (IH, m), 5.05-4.95 (2H, m), 2.5-1.4 (9H, m), 1.25 (s, 9H): B; 5.85-5.65 (IH, m), 5.05-4.95 (2H, m), 4.15-4.05 (IH, m), 2.8-1.3 (9H, m), 1.14 (s, 9H): C; 5.85-5.65 (IH, m), (5.05-4.95 (2H, m), 3.95-3.85 (IH, m), 2.6-1.3 (9H, m), 1.10 (s, 9H). Combined fractions B and C (1.9 g) was dissolved in ethanol (20 mL), hydrazine hydrate (2 mL) was added and the resulting solution was stirred at RT for 2h. The mixture was concentrated and the residue dissolved in ether (50 mL). The solution was washed with IN hydrochloric acid (10 mL), dried (MgSO4) and re-concentrated to give 7-allyl-3-(l,l-dimethylethyl)-4,5,6,7-tetrahydro-lH-indazole as a gum, 1.8 g. 1H NMR δ (ppm) (CDCl3): 5.9-5.75 (IH, m), 5.15-5.05 (2H, m), 3.15-2.85 (2H, m), 2.5-2.7 (2H, m), 2.5- 2.35 (IH, m), 1.95-1.85 (2H, m), 1.75-1.5 (2H, m), 1.45 (9H, m). Step 2:
Sodium hydride 60% dispersed in oil (0.4 g, 0.01 mol) was added portionwise to a solution of 7-allyl-3- (l,l-dimethylethyl)-4,5,6,7-tetrahydro-lH-indazole [Step 1] (1.8 g, 0.082 mol) in dry DMF stirring at rt. After 30 min, Intermediate 5 (3 g, 0.01 mol) was added and the mixture stirred at room temperature for 18 h. The mixture was partitioned between ether (100 mL and water (50 mL). The organic phase was separated, dried (MgSO4), and concentrated to an oil which was purified by MPLC on silica with
EtOAc:Ηexane 0->10% as eluant to give 1.5 g of 7-allyl-(3-(l,l-dimethylethyl)-l-{l-(4-methyl-l-[4-
(trifluoromethyl) phenyl]pentyl)}-4,5,6,7-tetrahydro-lH-indazole as an oil.
Step 3:
RuCl3 hydrate (15 mg) was added to mixture of 7-allyl-(3-(l,l-dimethylethyl)-l-{l-(4-methyl-l-[4- (trifluoromethyl) phenyl]pentyl)}-4,5,6,7-tetrahydro-lH-indazole [Step 2] (1 g, 0.002 mol) and sodium periodate (1.7 g, 0.008 mol) in a mixture Of CCl4 (4 mL), CH3CN (4 mL) and water (6 mL) stirring rapidly at room temperature. After 24 h the mixture was partitioned between water (10 mL) and DCM (3x50 mL). The organic phase was concentrated and the residue purified by MPLC on silica with DCM:MeOH 0- >10% as eluant followed by RP HPLC on a C-18 column eluting with 70%CH3CN:0.1%TFAaq. as eluant to give (3-(l,l-dimethylethyl)-l-{l-(4-methyl-l-[4-(trifluoromethyl) phenyl]pentyl)}-4,5,6,7-tetrahydro- lH-indazol-7-yl)acetic acid as a 1:1 mixture of diastereomers. MS ES(M+1), 465. 1H NMR δ (ppm) (CDCl3): 7.56-7.51(2H of Diast A + IH of Diast B), 7.37, (1 H Diast B, d, J = 8 Hz), 4.95-5.05 (IH A + IH B, m), 3.4-3.3 (IH A, m), 3.1-3.2 (IH B, m), 2.7-1.4 (13H A+B, m), 1.33 and 1.31 (9H A+B, 2s), 0.88 and 0.84 (6H A+B, d, J = 6 Hz).
Example 17
Figure imgf000032_0001
Prepared according to the method of Intermediate 3 using 1-cyclohexene-l -methanol in Step 1; m/z ES+ (M+H+) 490. Step 2
Step 1 was converted to the corresponding acid according to the method for Example 5, step 6. m/z ES+ (M+H+) 462.
Example 18
Figure imgf000032_0002
Step 1
Figure imgf000032_0003
Prepared using the method of Intermediate 3 using 1-cyclohexene-l -methanol in Step 1 and Intermediate 7 in step 4; m/z ES+ (M+H+) 524.
Step 2 Step 1 was converted to the corresponding acid according to the method for example 5, step 6. m/z ES+ (M+H+) 496.
Examples 19-22
Figure imgf000033_0001
Prepared according to the following typical procedure (X = morpholine): Step 1
To a stirred solution of the Intermediate 6 (60 mg, 0.13 mmol) and morpholine (11 mg, 0.13 mmol) in chloroform (3ml) was added sodium triacetoxyborohydride (82 mg, 0.39 mmol) and the resulting mixture was stirred at room temperature for 16 h. The mixture was quenched with sat. NaHCO3(aq), and filtered through a phase-separation cartridge, washing with DCM. Concentration under reduced pressure gave the crude ester as a colourless oil, which was taken on crude to step 2. Step 2
Step 1 was converted to the corresponding acid according to the method for example 5, step 6. IH NMR (400 MHz, CDC13): δ 7.54 (d, 2 H), 7.16 (t, 2 H), 5.23 (m, 1 H), 3.70 (t, 4 H), 3.42 (s, 2 H), 3.22 (d, 1 H), 2.53-0.70 (m, 26 H) m/z ES+ (M+H+) 507.
Figure imgf000033_0002
Example 23
Figure imgf000034_0001
To the iodide from Example 15 (320 mg, 0.54 mmol) in dioxane (4 ml) were added pyridine-4-boronic acid (100 mg, 0.81 mmol), bis(diphenylphosphino)ferrocene dichloropalladium(II) (20 mg, 5 mol%) and 2M Na2CO3 (aq). The mixture was subjected to microwave radiation to heat at 1700C for 15 min. Reaction was diluted with water and extracted with EtOAc (x3). The organic extracts were washed with brine, dried (magnesium sulfate), filtered and evaporated. The residue was purified by flash chromatography (SiO2, 9:1 DCM/MeOH to 5:1 DCM/MeOH) to give a white solid as mix of diastereoisomers. IH NMR δ (ppm)(CDCl3): 8.53 (2H, br), 7.60 (2H, d, J = 8.0 Hz), 7.27 (4H, m), 5.27 (IH, br), 3.39 (IH, br), 2.61- 0.87 (2OH, m). m/z (ES) 527 (MH+).
Examples 24-38
Figure imgf000034_0002
Step 1
Figure imgf000034_0003
(a) To a stirred solution of Intermediate 3 (28.1 g, 66.7 mmol) in dry THF (300ml) cooled to 00C was added triethylamine (18.6ml, 133 mmol) followed by trimethylacetyl chloride (9.8 ml, 80 mmol). The resulting mixture was stirred for 10 min, prior to addition of a mixture of (S)-5-benzyl-2-oxazolidinone (14.19, 80 mmol) and lithium chloride (8.03g, 189 mmol) as a solid. Stirring was continued for a further 16h, before solvent removal under reduced pressure. The residue was partitioned between water and ethyl acetate, and the aqueous phase was extracted (3 x ethyl acetate). The combined organic phases were washed (brine), dried (sodium sulfate) and concentrated under reduced presssure to give an oil, which was purified by flash chromatography (Biotage SPl system, gradient elution from 3-30% diethyl ether / isohexane). The top eluting diastereoisomer was isolated as a white solid (15.5g, 40%) was taken on to the next step.
(b) To a stirred solution of the the oxazolidinone (10.4g, 17.9 mmol) in (3:1) THF-water (100ml) was added lithium hydroxide monohydrate (1.5g, 35.8 mmol), and the resulting mixture was stirred at room temperature for 16h. The solvent was removed under reduced pressure and the residue was partitioned between 2M HCl (aq) and EtOAc. The aqueous phase was extracted with EtOAc, the combined organic phases were washed (brine), dried (sodium sulfate) and concntrated under reduced pressure to give an oil, which was dissolved in DMF (50ml). Potassium carbonate (7.43g, 53.7 mmol) followed by iodomethane (3.35ml, 53.7 mmol) was added and the mixture was heated to 400C for 16h. The mixture was filtered, and the filtrate was concentrated under reduced pressure to give an oil, which was partitioned between EtOAc and water. The aqueous phase was extracted with EtOAc, the combined organic phases were washed (brine), dried (sodium sulfate) and concntrated under reduced pressure to give an oil which was purified by flash chromatography (Biotage SPl, gradient elution from 2-20% EtOAc / isohexane to give a colourless oil (4.Og, 51%). IH NMR (400 MHz, CDC13): δ 7.55 (d, 2 H), 7.14 (d, 2 H), 5.72 (s, 1 H), 5.21 (dd, 1 H), 3.60 (s, 3 H), 3.23 (d, 1 H), 2.55-2.31 (m, 4 H), 2.21-2.03 (m, 2 H), 1.87 (s, 3 H), 1.76 (br, 4 H), 1.30-1.24 (m, 2 H), 1.02 (t, 1 H), 0.94-0.86 (m, 6 H). mlz (ES+) 436 (M+H+). Step 2(a)
The product of Step 1 was treated with NBS as described in Example 1 Step 1 to provide the 3-bromo derivative. IH NMR (400 MHz, CDC13): δ 7.57 (d, 2 H), 7.16 (t, 2 H), 5.23 (dd, 1 H), 3.60 (d, 3 H), 3.24 (d, 1 H), 2.54-2.32 (m, 4 H), 2.20-2.04 (m, 3 H), 1.85-1.73 (m, 6 H), 1.27-1.19 (m, 2 H), 0.98- 0.90 (m, 7 H). Alternative Step 2(b)
The product of Step 1 was treated with N-iodosuccinimide as in Example 15 to provide the 3-iodo derivative. IH NMR (500 MHz, CDC13): δ 7.57 (d, 2 H), 7.14 (d, 2 H), 5.25 (dd, 1 H), 3.59 (s, 3 H), 3.23 (d, 1 H), 2.49-2.27 (m, 4 H), 2.19-2.04 (m, 2 H), 1.89 (s, 3 H), 1.82-1.65 (m, 2 H), 1.63-1.51 (m, 1 H) 1.36-1.20 (m, 2 H), 0.97-0.83 (m, 8 H). Step 3
The product from Step 2(b) (0.162 mmol), 4-(trifluoromethyl)benzeneboronic acid (46 mg, 0.243 mmol), Pd(dppf)Cl2 (5.9 mg, 0.008 mmol) and 2M sodium carbonate solution (324 μl, 0.694 mmol) in dioxane (2 ml) were stirred and heated at 1000C for 18 hours. The mixture was allowed to cool to room temperature and then concentrated to dryness. The crude residue and lithium hydroxide (44 mg, 1.91 mmol) in 5: 1 dioxane-water (2 ml) were stirred and heated at 1000C for 18 hours. The mixture was cooled to room temperature and concentrated to dryness. The residue was diluted with DCM (2 ml) and water (2 ml) and adjusted to pH 5/6 with dilute hydrochloric acid. The organic phase was separated using a phase separation cartridge and concentrated to dryness. The residue was dissolved in DMSO (1 ml) and Example 24 was isolated using mass-directed preparative HPLC.
Using this method, and employing Step 2(a) or 2(b) as indicated, the following were prepared:
Figure imgf000036_0002
Examples 39-47
Following procedure similar to those described for Example 5-13, the following were also prepared:
Figure imgf000036_0001
Figure imgf000036_0003
Figure imgf000037_0001
Glossary
KHMDS potassium hexamethyldisilazide
DCM dichloromethane
THF tetrahydrofuran
DMF dimethylformamide
RT room temperature
DIBAH diisobutylaluminium hydride
TFA trifluoroacetic acid
EtOAc ethyl acetate
EtOH ethanol
Et2O diethyl ether
NBS N-bromosuccinimide

Claims

CLAIMS:
1. A compound of formula I:
Figure imgf000038_0001
(I) wherein V represents a bond, CH2 or CH2CH2; X represents CRla or N; Y represents CO2H or tetrazole;
Ar represents phenyl which optionally bears up to 3 substituents independently selected from hydrocarbon groups of up to 6 carbon atoms and (CH2)m-Z where m is 0, 1 or 2 and Z represents halogen, N3, CN, CF3, OCF3 or OR4;
R1 represents halogen, CN, R4CO, CF3, CH2N(R4)2, a branched Ci.iOalkyl group, a Ci.iOalkenyl group, or a non-aromatic cyclic group of up to 7 ring atoms of which up to 2 may be selected from N, O and S; or when X is CRla, R1 and Rla may complete a fused cycloalkene ring of 5, 6 or 7 members which is optionally substituted with up to 2
Figure imgf000038_0002
groups; Rla represents H or
Figure imgf000038_0003
or combines with R1 as defined above; with the proviso that when X is CH, R1 is not t-butyl; each R2 is independently H or
Figure imgf000038_0004
R3 is H, hydrocarbon containing up to 10 carbon atoms,
Figure imgf000038_0005
or heterocyclylCi. 4alkyl, any of which optionally bears up to 3 substitutents selected from halogen and CF3, or 1 substituent selected from and
Figure imgf000038_0006
where "heterocyclyl" refers to aromatic or nonaromatic rings of 5 or 6 atoms of which 1, 2 or 3 are selected from N, O and S;
R4 represents H or a hydrocarbon group of up to 7 carbon atoms, optionally substituted with halogen, CN, CF3, OH,
Figure imgf000038_0007
or two R4 groups attached to a nitrogen atom may complete ring selected from pyrrolidine, piperidine, morpholine, thiomorpholine, tetrahydropyridine and piperazine, any of which rings optionally bearing a substituent selected from CF3,
Figure imgf000038_0008
and phenyl; R5 represents R4 that is other than H; p is 0, 1 or 2; and
R6 represents Ci-6alkyl, C2-6alkenyl or phenyl, benzyl or heteroaryl, said phenyl, benzyl or heteroaryl optionally bearing up to 3 substituents selected from halogen, CN, CF3, OCF3, OR4, CO2R4,
Figure imgf000038_0009
or a pharmaceutically acceptable salt or hydrate thereof.
2. A compound according to claim 1 wherein R1 is selected from Cl, Br, I, CN, R4CO, CF3, CH2N(R4)2, branched Ci-6alkyl, and non-aromatic cyclic groups of up to 7 ring atoms of which up to 2 may be selected from N, O and S.
3. A compound according to claim 2 wherein R1 represents Cl, Br, I, CN or R4CO and X represents CRla.
4. A compound according to claim 1 wherein X represents CRla, Rla represents
Figure imgf000039_0001
and R1 represents halogen, CN or R4CO.
5. A compound according to claim 1 wherein X represents CH and R1 represents branched Ci.ioalkyl or a non-aromatic cyclic group of up to 7 ring atoms of which up to 2 may be selected from N, O and S.
6. A compound according to claim 1 wherein X represents CRla and R1 and Rla complete a fused cycloalkene ring of 5, 6 or 7 members which is optionally substituted with up to two
Figure imgf000039_0002
groups.
7. A compound according to any previous claim wherein V represents CH2, p is 0 and both R2 groups represent H.
8. A compound according to any previous claim wherein Ar represents 4- trifluoromethylphenyl.
9. A pharmaceutical composition comprising a compound according to any previous claim and a pharmaceutically acceptable carrier.
10. A compound according to any of claims 1-8 for use in therapy.
11. The use of a compound according to any of claims 1 -8 for the manufacture of a medicament for treatment or prevention of a disease associated with deposition of Aβ in the brain.
12. A method of treating or preventing a disease associated with deposition of Aβ in the brain comprising administering to a patient in need thereof a therapeutically effective amount of a compound according to claim 1.
PCT/GB2006/050368 2005-11-10 2006-11-03 Tetrahydroindole derivatives for treatment of alzheimer's disease WO2007054739A1 (en)

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AU2006313537A AU2006313537A1 (en) 2005-11-10 2006-11-03 Tetrahydroindole derivatives for treatment of Alzheimer's disease
AT06808732T ATE519740T1 (en) 2005-11-10 2006-11-03 TETRAHYDROINDOLE DERIVATIVES FOR THE TREATMENT OF ALZHEIMER'S DISEASE
EP06808732A EP1948603B1 (en) 2005-11-10 2006-11-03 Tetrahydroindole derivatives for treatment of alzheimer's disease
CA002628934A CA2628934A1 (en) 2005-11-10 2006-11-03 Tetrahydroindole derivatives for treatment of alzheimer's disease
US12/084,814 US8203004B2 (en) 2005-11-10 2006-11-03 Tetrahydroindole derivatives for treatment of alzheimer's disease
JP2008539507A JP2009515864A (en) 2005-11-10 2006-11-03 Tetrahydroindole derivatives for the treatment of Alzheimer's disease

Applications Claiming Priority (2)

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GBGB0522908.3A GB0522908D0 (en) 2005-11-10 2005-11-10 Therapeutic agents

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AT (1) ATE519740T1 (en)
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CA (1) CA2628934A1 (en)
GB (1) GB0522908D0 (en)
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WO2010071741A1 (en) 2008-12-16 2010-06-24 Merck Sharp & Dohme Corp. Triazole derivatives for treatment of alzheimer's disease
WO2015011396A1 (en) 2013-07-23 2015-01-29 Les Laboratoires Servier Novel derivatives of indole and pyrrole, method for the production thereof and pharmaceutical compositions containing same

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EP3862356B1 (en) 2018-09-28 2024-04-03 Kao Corporation Method for producing cyclic enol ether compound
IL286361B2 (en) 2019-03-18 2023-11-01 Kao Corp Method for producing ? – allylated cycloalkanone

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WO2010071741A1 (en) 2008-12-16 2010-06-24 Merck Sharp & Dohme Corp. Triazole derivatives for treatment of alzheimer's disease
WO2015011396A1 (en) 2013-07-23 2015-01-29 Les Laboratoires Servier Novel derivatives of indole and pyrrole, method for the production thereof and pharmaceutical compositions containing same
EP3168217A1 (en) 2013-07-23 2017-05-17 Les Laboratoires Servier Novel indole and pyrrole derivatives, method for preparing same and pharmaceutical compositions containing same

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CA2628934A1 (en) 2007-05-18
US8203004B2 (en) 2012-06-19
EP1948603B1 (en) 2011-08-10
EP1948603A1 (en) 2008-07-30
AU2006313537A1 (en) 2007-05-18
ATE519740T1 (en) 2011-08-15
GB0522908D0 (en) 2005-12-21
JP2009515864A (en) 2009-04-16
US20100016308A1 (en) 2010-01-21

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