EP3464319A2 - Intermediates and processes to prepare anidulafungin - Google Patents

Intermediates and processes to prepare anidulafungin

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Publication number
EP3464319A2
EP3464319A2 EP15849205.8A EP15849205A EP3464319A2 EP 3464319 A2 EP3464319 A2 EP 3464319A2 EP 15849205 A EP15849205 A EP 15849205A EP 3464319 A2 EP3464319 A2 EP 3464319A2
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EP
European Patent Office
Prior art keywords
formula
anidulafungin
compound
active ester
active
Prior art date
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EP15849205.8A
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German (de)
French (fr)
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EP3464319A4 (en
Inventor
Anand Vijaykumar MANTRI
Yogish Kumar HUCHANNA
Talluri Bhushaiah CHOWDARY
Gaurav Kulkarni
Ganga Ramu VASANTHAKUMAR
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Individual
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Individual
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Publication of EP3464319A2 publication Critical patent/EP3464319A2/en
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K7/00—Peptides having 5 to 20 amino acids in a fully defined sequence; Derivatives thereof
    • C07K7/50—Cyclic peptides containing at least one abnormal peptide link
    • C07K7/54—Cyclic peptides containing at least one abnormal peptide link with at least one abnormal peptide link in the ring
    • C07K7/56—Cyclic peptides containing at least one abnormal peptide link with at least one abnormal peptide link in the ring the cyclisation not occurring through 2,4-diamino-butanoic acid

Definitions

  • the present invention relates to novel process to prepare an antifungal agent, Anidulafungin.
  • the process involves synthesis of novel active esters which can be used in the synthesis of Anidulafungin,.
  • the active esters are prepared in situ and reacted further to produce Anidulafungin or isolated and reacted further to produce Anidulafungin.
  • the active esters are isolated and characterized by RP- HPLC, ⁇ NMR, MS and melting point.
  • the active esters are storage stable and can be prepared and stored for longer duration and can be used as and when required.
  • the invention also relates to a novel method of preparation of active esters which are further used in in situ form or isolated form for preparation of an antifungal agent, Anidulafungin (a cyclic peptide antifungal agent).
  • the invention also relates to novel method of preparing Anidulafungin in simple and economical way by subjecting the active esters to acylation reaction with Echinocandin B without use of any expensive reagent / coupling agent.
  • the active ester of present invention is represented by formula I
  • Anidulafungin a cyclic peptide synthesized from the novel active ester of the present invention is represented by formula II
  • Anidulafungin has proven efficacy against esophageal candidiasis, but its main use will probably be in invasive Candida infection, it may also have application in treating invasive Aspergillus infection. It is a member of the class of antifungal drugs known as the echinocandins. Anidulafungin works by way of concentration-dependent inhibition of 1 ,3-beta-D-glucan synthase resulting in reduced formation of 1 ,3-beta-D-glucan, which is an essential polysaccharide comprising one-third of the majority of Candidaspp. cell walls. This decreased glucan production leads to osmotic instability and thus cellular lysis.
  • Fmoc-P-resin serves as a carrier
  • a solid phase polypeptide synthetic method is adopted to gradually couple amino acid with an Fmoc protecting group from the C end to the N end, and then the protecting group is deprived through splitting, intramolecular reaction and liquid phase condensation to obtain the anidulafungin.
  • EP0561639; JP1994056892 discloses a method for the synthesis of anidulafungin, by acylation of cyclic hexapeptide (Echinocandin B) with 4"- n- pentyloxy- ⁇ , ⁇ : 4',1 " - terphenyl-4-carboxylic acid 2,4,5-trichlorophenol ester resulted in target product.
  • the above method of synthesis employs a condensing agent N, N-dicyclohexyl carbodiimide which is an expensive reagent. This may possibly generate N, N- dicyclohexyl urea which is very difficult to remove.
  • the present invention relates to novel process for preparation of Anidulafungin involving synthesis of novel active ester as novel key intermediates.
  • the active esters can be used either in situ form or they can be isolated and used in the preparation of Anidulafungin in isolated form.
  • the esters are found storage stable and can be stored before reacting with Echinocandin B.
  • the active esters even in crude stage has more than 95 % purity and there is no need to further purify them.
  • the first object of the present invention is to provide novel active esters, in particular novel key intermediate for preparing Anidulafungin, which is an antifungal agent.
  • the novel active esters are esters of (4"-(pentyloxy)-[l,r:4', l "- terphenyl]-4-carboxylic acid).
  • the active ester can be prepared in situ and reacted further to produce Anidulafungin or can be isolated and stored before use. Two such active esters have been isolated and characterized. They have purity of greater than 95 % even in crude state and have been found to be storage stable when stored at 2-8°C for months. Hence they can be stored for further synthesis of Anidulafungin.
  • Second object of the present invention is to provide process to prepare novel active esters of (4"-(pentyloxy)-[l ,l ':4',l "-terphenyl]-4-carboxylic acid)., which is simple and economical.
  • Third object of the present invention is to provide a process to prepare Anidulafungin from novel active esters of (4"- (pentyloxy)-[l,l':4',l "-terphenyl]-4-carboxylic acid) with another key intermediate, Echinocandin B or a salt thereof, preferably in presence of a base.
  • the present invention provides novel key intermediate, in particular novel active esters of 4"-(pentyloxy)-[l, -.4',l "- terphenyl]-4-carboxylic acid represented by formula I as below:
  • the active esters of 4"-(pentyloxy)-[l,r:4',r'-terphenyl]-4- carboxylic acid can be formed in situ or can be isolated further.
  • the active esters wherein both the R' and R" are methyl or phenyl are successfully isolated, purified and characterized. These esters are found storage stable.
  • the isolated esters are characterized for physicochemical and spectroscopic methods and their purity is determined by HPLC.
  • the active ester purity was confirmed by RP- HPLC and it is further characterized by MS, ⁇ NMR.
  • This active ester is shelf stable and can be stored in a dry condition for months after its preparation. This would enable to prepare and store the active ester and use it when needed for synthesis of Anidulafungin.
  • the process involves reacting (4"-(pentyloxy)-[l ,r:4',l"-terphenyl]-4-carboxylic acid)/ formula III compound with 2-chloro-4,6-dimethoxy-l ,3,5-triazine (CDMT) or 2-chloro-4,6-diphenyloxy-l ,3,5-triazine (CDPT) in presence of base in a solvent, preferably aprotic solvent. Number of bases and solvents can be used. The preferred base is N-methylmorpholine and the preferred solvent is DMF.
  • the reaction of (4"-(pentyloxy)-[l,l ':4',l"-terphenyl]-4-carboxylic acid) with CDMT in presence of base in DMF as solvent is as follows:
  • This step viz. isolation is optional
  • the first step involves reacting, CDMT (or CDPT) with a base to generate salt.
  • each of Ri, R 2 , R 3 independently is hydrogen, alkyl, aryl, arylalkyl, cycloalkyl, heterocycloalkyl, heterocyclic groups or alternatively Ri, R 2 and R3 together with Nitrogen or any two of the Rl , R2 and R3 together with Nitrogen form a ring which can be heterocycloalkyl, or heterocyclic and any such ring is optionally substituted by alkyl, aryl, arylalkyl, cycloalkyl, heterocycloalkyl, heterocyclic groups, nitro, halo, amino or substituted amino groups, or alternatively Rj, R 2 and R 3 together with Nitrogen form guanidine or substituted guanidine.
  • the base is N-methylmorpholine.
  • the N-methylmorpholine reacts with CDMT (or CDPT) and generates in situ 4-(4,6-dimethoxy- 1 ,3,5- triazin-2-yl)-4-methylmorpholin-4-iumchloride, DMTMM [or 4-(4,6-diphenoxy- l ,3,5-triazin-2-yl)-4-methylmorpholin-4-ium chloride, DPTMM.]
  • DMTMM or DPTMM or any salt generated by reaction of a base with CDMT or CDPT can be isolated or reacted in situ [(DMTMM) or (DPTMM)] further with (4"-(pentyloxy)-[l,l':4', l"-terphenyl]-4-carboxylic acid), a Formula III compound to produce active ester.
  • DMTMM DMTMM or DPTMM or any salt generated by reaction of a base with CDMT or CDPT
  • DMTMM or DPTMM or any salt generated by reaction of a base with CDMT or CDPT can be isolated or reacted in situ [(DMTMM) or (DPTMM)] further with (4"-(pentyloxy)-[l,l':4', l"-terphenyl]-4-carboxylic acid), a Formula III compound to produce active ester.
  • the active ester which is compound of formula I can be further isolated optionally.
  • any salt generated by reaction of a base with CDMT or CDPT can be isolated. Such isolated salt is reacted with compound of formula III to produce active ester of formula I. In this process DMTMM or DPTMM or any such salt is used as a coupling agent for preparation of an active ester.
  • Further aspect of the invention is to provide process of preparation of an antifungal agent, Anidulafungin, a compound of formula II from the novel active ester viz. compound of Formula I-A (or with compound of Formula I-B) by reacting it with Echinocandin B of formula IV as follows:
  • isolated novel ester is reacted with Echinocandin B to produce Anidulafungin.
  • Sheet 2 of Sheet 9 - 1 H-NMR of Formula I-A compound active ester (expanded region from 6.7 to 8.5 ⁇ region of figure represented on Sheet 1)
  • Sheet 3 of Sheet 9 - ⁇ -NMR of Formula I- A compound active ester (expanded region from 0.5 to 4.4 ⁇ region of figure represented on Sheet 1)
  • Sheet 4 of Sheets 9 - RP-HPLC profile of Formula I-A compound active ester Sheet 5 of Sheets 9 - Mass spectra of Formula I-A compound active esterSheet 6 of Sheet 9 - ⁇ -NMR of Formula I-B compound active ester in CDC1 3
  • CDMT 2-chloro-4,6-dimethoxy-l ,3,5-triazine
  • CDPT 2-chloro-4,6-diphenyloxy-l ,3,5-triazine
  • DPTMM 4-(4,6-diphenyloxy-l,3,5-triazin-2-yl)-4-methylmorpholin-4-ium chloride
  • Anidulafungin has proven efficacy against esophageal candidiasis, but its main use will probably be in invasive Candida infection, it may also have application in treating invasive Aspergillus infection. It is a member of the class of antifungal drugs known as the Echinocandins.
  • Anidulafungin works by way of concentration-dependent inhibition of 1 ,3- beta-D-glucan synthase resulting in reduced formation of 1 ,3-beta-D-glucan, which is an essential polysaccharide comprising one-third of the majority of Candida spp. cell walls. This decreased glucan production leads to osmotic instability and thus cellular lysis.
  • the first aspect of the present invention relates to novel active esters represented by a compound of formula I that can be used further to prepare Anidulafungin (Formula II).
  • Formula I compounds can be prepared in situ and reacted further as the are or active esters are isolated and further reacted.
  • This active esters are shelf stable and can be stored for several months after its preparation. This would enable one to prepare and store the active esters and use it when needed for synthesis of Anidulafungin. This would also enable one to transport active esters from one lab to another for further scale up of Anidulafungin from development scale to commercial level or one commercial scale to higher commercial scale. This would also enable one to obtain ready key intermediates of Anidulafungin from market for further synthesis. Further availability of these esters provide means for one pot synthesis of Anidulafungin.
  • each active ester is subjected to acylation reaction with Echinocandin B to produce Anidulafungin, preferably in presence of a base selected from diisopropylethyl amine, N-methyl morpholine (NMM), pyridines, lutidines, picolines, dimethylaminopyridine, and collidines, and any combination thereof.
  • a base selected from diisopropylethyl amine, N-methyl morpholine (NMM), pyridines, lutidines, picolines, dimethylaminopyridine, and collidines, and any combination thereof.
  • the most preferred base is diisopropylethyl amine and N-methyl morpholine.
  • the base N-methyl morpholine is most preferred as it maintains a pH of reaction below 9, preferably below 8.5 and most preferably below 8. At higher pH conditions peptides like Echinocandin might degrade leading to impure Anidulafungin.
  • the reactants should be such that they would react to form Anidulafungin at pH below 9 and below 8.5 and preferably at pH 7 - 8. All esters would not be able to react with Echinocandin at this pH range and hence ester should be carefully chosen.
  • HOBT ester as disclosed in W0961 1210 that has hydroxy benzotriazole is highly hygroscopic and requires of l-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDO) which is very expensive.
  • EEO l-ethyl-3-(3-dimethylaminopropyl) carbodiimide
  • This patent mentions use of several bases such as alkali metal carbonates which tend to provide higher pH ranges and might degrade peptide such as Echinocandin B.
  • the reaction completes in about 8 - 10 hrs, preferably in 4-5 hrs and results with quantitative yield of high purity (crude purity is at least 95 %) Anidula
  • HPLC Chromatogram as provided in sheet 4 indicates that purity of Formula I-A compound viz. CDMT ester is 98.3 %
  • HPLC Chromatogram as provided in sheet 8 indicates that purity of Formula I-A compound viz. CDPT ester is 97.3 %
  • CDMT ester elutes at the retention time of 24.9 and CDPT ester elutes at the retention time of 21.3
  • the most desired properties of active esters of Formula I-A and I-B include i) purity of esters without subjecting to purification step and ii) storage stability for at least 1 month, preferably greater than 3 months and most preferably greater than 6 months.
  • esters are further reacted with Echinocandin B to produce Anidulafungin.
  • the invention relates to process of preparation of novel active ester.
  • An active ester in accordance with the present invention is prepared by process in which compound of the Formula III viz. (4"-(pentyloxy)-[l , l ':4', l "- terphenyl]-4-carboxylic acid) is reacted with 2-chloro-4,6-dimethoxy- 1 ,3,5- triazine (CDMT) or 2-chloro-4,6-diphenoxy-l ,3,5-triazine (CDPT).
  • CDMT 2-chloro-4,6-dimethoxy- 1 ,3,5- triazine
  • CDPT 2-chloro-4,6-diphenoxy-l ,3,5-triazine
  • the step is carried out in a solvent, preferably in an aprotic solvent, selected from tetrahydrofuran (THF), dimethylformamide (DMF), toluene, 2- methyltetrahydrofuran, N-methyl-2-pyrrolidone (NMP), and any combination thereof, and is preferably tetrahydrofuran.
  • a solvent preferably in an aprotic solvent, selected from tetrahydrofuran (THF), dimethylformamide (DMF), toluene, 2- methyltetrahydrofuran, N-methyl-2-pyrrolidone (NMP), and any combination thereof, and is preferably tetrahydrofuran.
  • THF tetrahydrofuran
  • DMF dimethylformamide
  • NMP N-methyl-2-pyrrolidone
  • the step is carried out in presence of base.
  • the base is selected from N-methylmorpholine (NMM), ⁇ , ⁇ , ⁇ , ⁇ - tetramethylguanidine, pyridine, 4-picoline, 4-dimethylaminopyridine (DMAP), N- methylpiperidine and N,NN, N-tetramethylethylenediamine, and any combination thereof, and is preferably N-methylmorpholine (NMM).
  • novel active esters which are the active forms of the acid are generated in situ using CDMT or CDPT as a coupling agents.
  • novel ester prepared in situ can be isolated by evaporating the reaction mixture to dryness.
  • the crude mixtures were dissolved in aprotic solvent such as ethyl acetate and solution is filtered to remove unreacted reagents and salts generated.
  • the filtrate was evaporated to dryness and the solid obtained was stored in cold and anhydrous condition for prolonged usage.
  • the active ester of formula I - A when CDMT or its derivative (DMTMM) is used as a coupling agent is prepared as follows:
  • reaction is preferably carried out in aprotic solvents, most preferred are THF or DMF.
  • reaction is a two steps process.
  • 2-chloro-4,6- dimethoxy-1 ,3,5- triazine is reacted with N-methylmorpholine to form 4-(4,6- Dimethoxy-l ,3,5-triazin-2-yl)-4-methylmorpholin-4-ium chloride, DMTMM salt.
  • DMTMM is also referred as derivative of CDMT.
  • DMTMM salt can be further reacted in situ [(DMTMM)] or isolated for further reaction.
  • DMTMM salt in situ or in isolated form is reacted with compound of formula III which yields the formation of active ester of formula I.
  • CDPT is used to produce 4-(4,6-diphenyloxy-l ,3,5-triazin-2-yl)-4- methylmorpholin-4-ium chloride, DPTMM, which further can be used to prepare following active ester of Formula I-B
  • Ri, R 2 , R 3 independently is hydrogen , alkyl, aryl, arylalkyl, cycloalkyl, heterocycloalkyl, heterocyclic groups or alternatively R l s R 2 and R 3 together with Nitrogen or any two of the Ri, R 2 and R 3 together with Nitrogen form a ring which can be heterocycloalkyl, or heterocyclic and any such ring is optionally substituted by alkyl, aryl, arylalkyl, cycloalkyl, heterocycloalkyl, heterocyclic groups, nitro, halo, amino or substituted amino groups, or alternatively Ri, R 2 and R 3 together with Nitrogen form guanidine or substituted guanidine.
  • the isolation and purification process of active esters would depend upon the solvents in which such active ester is prepared.
  • the solvent is preferably aprotic and can be one selected from the group consisting of tetrahydrofuran (THF), dimethylformamide (DMF), toluene, 2-methyltetrahydrofuran, N-methyl- 2-pyrrolidone (NMP), and any combination thereof.
  • solvent is dimethylformamide or tetrahydrofuran.
  • the active ester prepared can be obtained by evaporating the solvent to obtain residue.
  • the residue is further dissolved in another solvent, preferably aprotic such as ethyl acetate and purified to obtain pure active ester.
  • aprotic such as ethyl acetate
  • dimethylformamide used as a solvent
  • the active ester dissolved therein is precipitated by adding water.
  • the precipitated active ester is dissolved in a solvent, preferably aprotic such as ethyl acetate and purified to obtain pure active ester.
  • Washings can be given before purification to remove unreacted materials.
  • Purity of active ester is usually about or greater than 95 %, preferably greater than
  • the invention relates to the process for preparation of an antifungal agent Anidulafungin from novel active ester, formula I compound.
  • an antifungal agent is prepared from the novel active ester (compound of formula II) wherein active ester prepared in situ is reacted with compound of formula IV (Echinocandin B) as follows:
  • the active ester prepared in situ is reacted with Formula IV compound (Echinocandin B) in presence of a base.
  • Isolated novel active ester can be similarly reacted with Formula IV compound (Echinocandin B) to produce Anidulafungin.
  • invention relates to process of preparing Aniduiafungin of Formula II from the active ester of formula I of the present invention.
  • the process can be described in details as follows:
  • the process for the preparation of an antifungal agent comprises reacting the active ester of formula I with compound of formula IV (Echinocandin B) preferably in presence of a base selected from diisopropylethyl amine, N- methylmorpholine (NMM), pyridines, lutidines, picolines, dimethylaminopyridine, and collidines, and any combination thereof.
  • a base selected from diisopropylethyl amine, N- methylmorpholine (NMM), pyridines, lutidines, picolines, dimethylaminopyridine, and collidines, and any combination thereof.
  • a base selected from diisopropylethyl amine, N- methylmorpholine (NMM), pyridines, lutidines, picolines, dimethylaminopyridine, and collidines, and any combination thereof.
  • the most preferred base diisopropylethyl amine.
  • an active ester prepared from CDPT can produce DPTMM which can be further reacted with (4"-(pentyloxy)-[l ,l ':4', l "-terphenyl]- 4-carboxylic acid), a compound of formula III to produce active ester which can be acylated with compound of formula IV (Echinocandin B) to produce Anidulafungin as follows:
  • DMTMM or DPTMM or their equivalents produced by using bases other than N-methylmorpholine can be isolated or reacted in situ with the Echinocandin B, a compound of formula IV to produce Anidulafungin.
  • the invention provides methods to prepare Anidulafungin using active esters of Formula I-A and I-B.
  • the active esters are reacted either in situ or in isolated form.
  • the active esters are obtained and isolated in pure form even in crude state. The purity is above 95 %.
  • These esters are storage stable and can be stored up to or even more than one year at 2-8°C.
  • solvent is selected from the group consisting of tetrahydrofuran (THF), dimethylformamide (DMF), Dimethylacetamide (DMA), toluene, 2-methyltetrahydrofuran, N-methyl-2-pyrrolidone (NMP), and any combination thereof
  • base is selected from the group consisting of diisopropylethylamine, N-methylmorpholine (NMM), pyridines, lutidines, picolines, dimethylaminopyridine, triethylamine and collidines, and any combination thereof.
  • Echinocandin B in DMF is charged NMM at room temperature.
  • the mixture is allowed to stir for overnight at room temperature.
  • mixture is stirred overnight at higher temperatures such as 40°C or 60°C.
  • Anidulafungin is isolated.
  • the best purity product (Anidulafungin) is obtained when overnight stirring is conducted at room temperature.
  • the crude product was further purified by flash column chromatography using dichloromethane as eluent.

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Abstract

The present invention relates to active esters of compound of Formula I-A and I-B which are used as key intermediates in the synthesis of Anidulafungin, an antifungal agent and process of preparation of said active esters. The invention also relates to process of preparing Anidulafungin from said active esters.

Description

INTERMEDIATES AND PROCESSES TO PREPARE ANIDULAFUNGIN
FIELD OF INVENTION
[0001] The present invention relates to novel process to prepare an antifungal agent, Anidulafungin. The process, involves synthesis of novel active esters which can be used in the synthesis of Anidulafungin,. The active esters are prepared in situ and reacted further to produce Anidulafungin or isolated and reacted further to produce Anidulafungin. The active esters are isolated and characterized by RP- HPLC, Ή NMR, MS and melting point. The active esters are storage stable and can be prepared and stored for longer duration and can be used as and when required. Further, the invention also relates to a novel method of preparation of active esters which are further used in in situ form or isolated form for preparation of an antifungal agent, Anidulafungin (a cyclic peptide antifungal agent).
[0002] The invention also relates to novel method of preparing Anidulafungin in simple and economical way by subjecting the active esters to acylation reaction with Echinocandin B without use of any expensive reagent / coupling agent.
The active ester of present invention is represented by formula I
Formula l-A whenR' and R" = CH3
Formula l-B when R' and R" = C6HS
Anidulafungin, a cyclic peptide synthesized from the novel active ester of the present invention is represented by formula II
Formula II BACKGROUND
[0003] Anidulafungin (IUPAC name N-
R,6S,9S,l lR,12R,14aS,15S,16S,20S,23S,25aS)-23-[(l S,2S)-l ,2-dihydroxy-2-(4- hydroxyphenyl)ethyl]-2, 1 1 ,12, 15-tetrahydroxy-6,20-bis[( 1 R)- 1 -hydroxy ethyl]- 16- methyl-5,8, 14, 19,22,25-hexaoxotetracosahydro- 1 H-dipyrrolo[2, 1 -c:2', 1 '- 1] [ 1 ,4,7, 10, 13 , 16]hexaazacyclohenicosin-9-yl } -4"-(pentyloxy)- 1 , 1 ' :4', 1 "- terphenyl-4-carboxamide and CAS Registry Number: 166663-25-8) is semisynthetic echinocandin which is represented by the Formula II
Formula II
[0004] Anidulafungin has proven efficacy against esophageal candidiasis, but its main use will probably be in invasive Candida infection, it may also have application in treating invasive Aspergillus infection. It is a member of the class of antifungal drugs known as the echinocandins. Anidulafungin works by way of concentration-dependent inhibition of 1 ,3-beta-D-glucan synthase resulting in reduced formation of 1 ,3-beta-D-glucan, which is an essential polysaccharide comprising one-third of the majority of Candidaspp. cell walls. This decreased glucan production leads to osmotic instability and thus cellular lysis.
[0005] Different routes of preparation of Anidulafungin are known in the art. US4293489, US4293482 discloses a class of antifungal cyclic peptide compounds and these are prepared by acylation of Echinocandin B which is obtained through enzymatic deacylation of cyclic peptide containing fatty acid side chain. The acylation of the free amino group of cyclic hexapeptide Echinocandin B with suitable side chain acids give a number of antifungal agents. [0006] CN 103145809 A' discloses method for preparing anidulafungin by solid phase-liquid phase full synthetic route. In this method Fmoc-P-resin serves as a carrier, a solid phase polypeptide synthetic method is adopted to gradually couple amino acid with an Fmoc protecting group from the C end to the N end, and then the protecting group is deprived through splitting, intramolecular reaction and liquid phase condensation to obtain the anidulafungin.
[0007] EP0561639; JP1994056892 discloses a method for the synthesis of anidulafungin, by acylation of cyclic hexapeptide (Echinocandin B) with 4"- n- pentyloxy-Ι , Γ: 4',1 " - terphenyl-4-carboxylic acid 2,4,5-trichlorophenol ester resulted in target product.
The above method of synthesis employs a condensing agent N, N-dicyclohexyl carbodiimide which is an expensive reagent. This may possibly generate N, N- dicyclohexyl urea which is very difficult to remove.
[0008] Journal of Medicinal Chemistry 1995, 38 (17), 3271 , Semisynthetic Chemical Modification of the Antifungal lipopeptidechinocandin B (ECB): Structure-Activity s of the lipophilic and geometric parameters of polyarylated acyl analogs of ECB (author Debono, M.; Turner, WW; LaGrandeur, L;. Burkhardt, FJ; Nissen, JS; Nichols, KK; Rodriguez, MJ; Zweifel, MJ; Zeckner, DJ; Gordee, RS;. et al), discloses a preparation method of anidulafungin by following synthetic route:
[0009] Notwithstanding the prior art, the present invention is neither taught nor rendered obvious thereby. The present invention relates to novel process for preparation of Anidulafungin involving synthesis of novel active ester as novel key intermediates. The active esters can be used either in situ form or they can be isolated and used in the preparation of Anidulafungin in isolated form. The esters are found storage stable and can be stored before reacting with Echinocandin B. The active esters even in crude stage has more than 95 % purity and there is no need to further purify them. Object of the invention
[0010] The first object of the present invention is to provide novel active esters, in particular novel key intermediate for preparing Anidulafungin, which is an antifungal agent. The novel active esters are esters of (4"-(pentyloxy)-[l,r:4', l "- terphenyl]-4-carboxylic acid). The active ester can be prepared in situ and reacted further to produce Anidulafungin or can be isolated and stored before use. Two such active esters have been isolated and characterized. They have purity of greater than 95 % even in crude state and have been found to be storage stable when stored at 2-8°C for months. Hence they can be stored for further synthesis of Anidulafungin. Second object of the present invention is to provide process to prepare novel active esters of (4"-(pentyloxy)-[l ,l ':4',l "-terphenyl]-4-carboxylic acid)., which is simple and economical. Third object of the present invention is to provide a process to prepare Anidulafungin from novel active esters of (4"- (pentyloxy)-[l,l':4',l "-terphenyl]-4-carboxylic acid) with another key intermediate, Echinocandin B or a salt thereof, preferably in presence of a base.
Summary of the Invention
[001 1] According to the first aspect, the present invention provides novel key intermediate, in particular novel active esters of 4"-(pentyloxy)-[l, -.4',l "- terphenyl]-4-carboxylic acid represented by formula I as below:
Formula l-A whenR' and R" = CH3
Formula l-B when R' and R" = C6H5
Under this aspect, the active esters of 4"-(pentyloxy)-[l,r:4',r'-terphenyl]-4- carboxylic acid can be formed in situ or can be isolated further. The active esters wherein both the R' and R" are methyl or phenyl are successfully isolated, purified and characterized. These esters are found storage stable. The isolated esters are characterized for physicochemical and spectroscopic methods and their purity is determined by HPLC. The active ester purity was confirmed by RP- HPLC and it is further characterized by MS, Ή NMR. This active ester is shelf stable and can be stored in a dry condition for months after its preparation. This would enable to prepare and store the active ester and use it when needed for synthesis of Anidulafungin.
[0012] According to the second aspect, there is provided process of preparation of novel active esters, a formula I compounds from ((4"-(pentyloxy)-[l , :4', l "- terphenyl]-4-carboxylic acid) (Formula III compound)).
Formula III
The process involves reacting (4"-(pentyloxy)-[l ,r:4',l"-terphenyl]-4-carboxylic acid)/ formula III compound with 2-chloro-4,6-dimethoxy-l ,3,5-triazine (CDMT) or 2-chloro-4,6-diphenyloxy-l ,3,5-triazine (CDPT) in presence of base in a solvent, preferably aprotic solvent. Number of bases and solvents can be used. The preferred base is N-methylmorpholine and the preferred solvent is DMF. The reaction of (4"-(pentyloxy)-[l,l ':4',l"-terphenyl]-4-carboxylic acid) with CDMT in presence of base in DMF as solvent is as follows:
Formula I ill CDMT
N-meUiyi morpholine
DMF
Formula I-A
This step viz. isolation is optional
Formula I-A
In the above reaction, instead of 2-chloro-4,6-dimethoxy-l ,3,5-triazine (CDMT), 2-chloro-4,6-diphenyloxy-l,3,5-triazine (CDPT) can be used to produce corresponding active ester.
[0013] Preparation of the active ester proceeds in two steps.
The first step involves reacting, CDMT (or CDPT) with a base to generate salt.
The general scheme of first step is represented as follows:
a, R',R" = OCH3
b, R'.R" = OC6H5
where each of Ri, R2, R3 independently is hydrogen, alkyl, aryl, arylalkyl, cycloalkyl, heterocycloalkyl, heterocyclic groups or alternatively Ri, R2 and R3 together with Nitrogen or any two of the Rl , R2 and R3 together with Nitrogen form a ring which can be heterocycloalkyl, or heterocyclic and any such ring is optionally substituted by alkyl, aryl, arylalkyl, cycloalkyl, heterocycloalkyl, heterocyclic groups, nitro, halo, amino or substituted amino groups, or alternatively Rj, R2 and R3 together with Nitrogen form guanidine or substituted guanidine.
[0014] Preferably, the base is N-methylmorpholine. The N-methylmorpholine reacts with CDMT (or CDPT) and generates in situ 4-(4,6-dimethoxy- 1 ,3,5- triazin-2-yl)-4-methylmorpholin-4-iumchloride, DMTMM [or 4-(4,6-diphenoxy- l ,3,5-triazin-2-yl)-4-methylmorpholin-4-ium chloride, DPTMM.]
CDMT NMM (DMTMM)
[0015] In second step, DMTMM or DPTMM or any salt generated by reaction of a base with CDMT or CDPT can be isolated or reacted in situ [(DMTMM) or (DPTMM)] further with (4"-(pentyloxy)-[l,l':4', l"-terphenyl]-4-carboxylic acid), a Formula III compound to produce active ester. Thus, inventors have successfully isolated and characterized active ester prepared by reacting DMTMM and (4"-(pentyloxy)-[l, l':4',l"-terphenyl]-4-carboxylic acid), a formula III compound as follows:
(DMTMM) OR DMTMM Formula III
Formula I-A
The active ester which is compound of formula I can be further isolated optionally.
Formula I-A
[0016] Similar to above, when a base used is other than N-methyl morpholine, any salt generated by reaction of a base with CDMT or CDPT can be isolated. Such isolated salt is reacted with compound of formula III to produce active ester of formula I. In this process DMTMM or DPTMM or any such salt is used as a coupling agent for preparation of an active ester.
Further aspect of the invention is to provide process of preparation of an antifungal agent, Anidulafungin, a compound of formula II from the novel active ester viz. compound of Formula I-A (or with compound of Formula I-B) by reacting it with Echinocandin B of formula IV as follows:
Formula I-A
/Formula IV
Formula II
Alternatively, isolated novel ester is reacted with Echinocandin B to produce Anidulafungin.
Echinocandin B/Formula IV
Formula II / Anidulafungin
Brief Description of the figures:
[0017]
Sheet 1 of Sheet 9 - Ή-NMR of Formula I-A compound active ester in CDCI3
Sheet 2 of Sheet 9 - 1 H-NMR of Formula I-A compound active ester (expanded region from 6.7 to 8.5 δ region of figure represented on Sheet 1) Sheet 3 of Sheet 9 - Ή-NMR of Formula I- A compound active ester (expanded region from 0.5 to 4.4 δ region of figure represented on Sheet 1)
Sheet 4 of Sheets 9 - RP-HPLC profile of Formula I-A compound active ester Sheet 5, of Sheets 9 - Mass spectra of Formula I-A compound active esterSheet 6 of Sheet 9 - Ή-NMR of Formula I-B compound active ester in CDC13
' Sheet 7 of Sheet 9 - Mass spectra of Formula I-B compound active ester
Sheet 8 of Sheet 9 - RP-HPLC profile of Formula I-B compound active ester Sheet 9 of Sheet 9 - RP-HPLC profile of Formula I-B compound active ester stored at 2-8°C for 2 months.
Detailed Description of the Invention
[0018] The details of the invention are as set forth.
All the technical and scientific terms used herein above have the meaning as commonly understood by a person skilled in the art to which the invention belongs, unless otherwise defined in this specification.
Following abbreviations are used and should be construed accordingly.
CDMT: 2-chloro-4,6-dimethoxy-l ,3,5-triazine
CDPT: 2-chloro-4,6-diphenyloxy-l ,3,5-triazine
DMTMM:4-(4,6-dimethoxy-l ,3,5-triazin-2-yl)-4-methylmorpholin-4-ium chloride
DPTMM:4-(4,6-diphenyloxy-l,3,5-triazin-2-yl)-4-methylmorpholin-4-ium chloride
NMM: N-methylmorpholine
TMG : N, N, N, N-tetramethy lguanidine
[0019] Anidulafungin (IUPAC name N-
{(2R,6S,9S,l l R,12R,14aS,15S,16S,20S,23S,25aS)-23-[(l S,2S)-l ,2-dihydroxy-2- (4-hydroxyphenyl)ethyl]-2,l 1,12,15-tetrahydroxy-6,20-bis[(lR)-l -hydroxyethyl]- 16-methyl-5,8, 14, 19,22,25-hexaoxotetracosahydro- lH-dipyrrolo[2, 1 -c:2', 1 '- 1] [ 1 ,4,7, 10, 13 , 16]hexaazacyclohenicosin-9-y 1 } -4"-(pentyloxy)- 1 , 1 ' :4', 1 "- terphenyl-4-carboxamide and , (CAS Registry Number: 166663-25-8) is semisynthetic echinocandin which is represented by the Formula II
[0020] Anidulafungin has proven efficacy against esophageal candidiasis, but its main use will probably be in invasive Candida infection, it may also have application in treating invasive Aspergillus infection. It is a member of the class of antifungal drugs known as the Echinocandins.
[0021] Anidulafungin works by way of concentration-dependent inhibition of 1 ,3- beta-D-glucan synthase resulting in reduced formation of 1 ,3-beta-D-glucan, which is an essential polysaccharide comprising one-third of the majority of Candida spp. cell walls. This decreased glucan production leads to osmotic instability and thus cellular lysis.
[0022] The first aspect of the present invention relates to novel active esters represented by a compound of formula I that can be used further to prepare Anidulafungin (Formula II). Formula I compounds can be prepared in situ and reacted further as the are or active esters are isolated and further reacted.
Formula l-A whenR' and R" = CH3
Formula l-B when R' and R" = C6H5
The two esters when R' and R" are both CH3 or R' and R" are both C6H5 as follows, such active ester has been successfully isolated, purified and characterized.
Formula I-A and
Formula I-B
[0023] This active esters are shelf stable and can be stored for several months after its preparation. This would enable one to prepare and store the active esters and use it when needed for synthesis of Anidulafungin. This would also enable one to transport active esters from one lab to another for further scale up of Anidulafungin from development scale to commercial level or one commercial scale to higher commercial scale. This would also enable one to obtain ready key intermediates of Anidulafungin from market for further synthesis. Further availability of these esters provide means for one pot synthesis of Anidulafungin. Further, each active ester is subjected to acylation reaction with Echinocandin B to produce Anidulafungin, preferably in presence of a base selected from diisopropylethyl amine, N-methyl morpholine (NMM), pyridines, lutidines, picolines, dimethylaminopyridine, and collidines, and any combination thereof. The most preferred base is diisopropylethyl amine and N-methyl morpholine. The base N-methyl morpholine is most preferred as it maintains a pH of reaction below 9, preferably below 8.5 and most preferably below 8. At higher pH conditions peptides like Echinocandin might degrade leading to impure Anidulafungin. Hence the reactants should be such that they would react to form Anidulafungin at pH below 9 and below 8.5 and preferably at pH 7 - 8. All esters would not be able to react with Echinocandin at this pH range and hence ester should be carefully chosen. For example, HOBT ester as disclosed in W0961 1210 that has hydroxy benzotriazole is highly hygroscopic and requires of l-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDO) which is very expensive. This patent mentions use of several bases such as alkali metal carbonates which tend to provide higher pH ranges and might degrade peptide such as Echinocandin B. [0024] The reaction completes in about 8 - 10 hrs, preferably in 4-5 hrs and results with quantitative yield of high purity (crude purity is at least 95 %) Anidulafungin.
The active esters are characterized as follows:
Physical characteristics For CDMT active Ester
1. Appearance: White powder.
2. Melting point: 182- 186 °C (Formula I- A)
Physical characteristics For CDPT active Ester
1. Appearance: White powder.
2. Melting point: 160 - 165 °C (Formula I-B)
Spectroscopic characteristics:
An active esters of formula I -A and 1-B are compound is? characterized by Ή- NMR spectra, mass spectra, and RP-HPLC profile; the details of which are provided in figures 1 -6.
'H-NMR spectra of Formula I-A and Formula I-B compounds.
The Ή NMR was recorded on Bruker 400 MHz using CDC13 as solvent. The details ofΉ NMR spectra are provided in a tabular form as follows:
2 H 8.25-8.27 d
* Additional peaks are due to water and solvent at δ 1.56 and 7.28 respectively. Mass Spectra - Mass Spectra of CDPT and CDMT esters are as reported in sheet 5 and 7.
Purity by HPLC
HPLC Chromatogram as provided in sheet 4 indicates that purity of Formula I-A compound viz. CDMT ester is 98.3 %
HPLC Chromatogram as provided in sheet 8 indicates that purity of Formula I-A compound viz. CDPT ester is 97.3 %
The novel active esters viz. CDMT ester elutes at the retention time of 24.9 and CDPT ester elutes at the retention time of 21.3
[0025] The most desired properties of active esters of Formula I-A and I-B include i) purity of esters without subjecting to purification step and ii) storage stability for at least 1 month, preferably greater than 3 months and most preferably greater than 6 months.
The stability of active esters of Formula I-B at 2-8°C for more than 2 months is as recorded in sheet 9.
The esters are further reacted with Echinocandin B to produce Anidulafungin.
This reaction is done either in situ or with isolated ester. When the ester is prepared and reacted in situ, its formation is confirmed by HPLC method.
In second aspect, the invention relates to process of preparation of novel active ester.
Process for in situ preparation of active ester is as follows:
[0026] An active ester in accordance with the present invention is prepared by process in which compound of the Formula III viz. (4"-(pentyloxy)-[l , l ':4', l "- terphenyl]-4-carboxylic acid) is reacted with 2-chloro-4,6-dimethoxy- 1 ,3,5- triazine (CDMT) or 2-chloro-4,6-diphenoxy-l ,3,5-triazine (CDPT). The step is carried out in a solvent, preferably in an aprotic solvent, selected from tetrahydrofuran (THF), dimethylformamide (DMF), toluene, 2- methyltetrahydrofuran, N-methyl-2-pyrrolidone (NMP), and any combination thereof, and is preferably tetrahydrofuran. The step is carried out in presence of base. The base is selected from N-methylmorpholine (NMM), Ν,Ν,Ν,Ν- tetramethylguanidine, pyridine, 4-picoline, 4-dimethylaminopyridine (DMAP), N- methylpiperidine and N,NN, N-tetramethylethylenediamine, and any combination thereof, and is preferably N-methylmorpholine (NMM).
Thus, the novel active esters which are the active forms of the acid are generated in situ using CDMT or CDPT as a coupling agents.
[0027] Further the novel ester prepared in situ can be isolated by evaporating the reaction mixture to dryness. The crude mixtures were dissolved in aprotic solvent such as ethyl acetate and solution is filtered to remove unreacted reagents and salts generated. The filtrate was evaporated to dryness and the solid obtained was stored in cold and anhydrous condition for prolonged usage.
The active ester of formula I - A when CDMT or its derivative (DMTMM) is used as a coupling agent is prepared as follows:
The reaction is preferably carried out in aprotic solvents, most preferred are THF or DMF.
N-methylmorpholine, THF/DMF
Formula I-A optional isolation
Formula I-A
[0028] The above reaction is a two steps process. In first step 2-chloro-4,6- dimethoxy-1 ,3,5- triazine is reacted with N-methylmorpholine to form 4-(4,6- Dimethoxy-l ,3,5-triazin-2-yl)-4-methylmorpholin-4-ium chloride, DMTMM salt. DMTMM is also referred as derivative of CDMT.
CDMT NMM (DMTMM)
DMTMM salt can be further reacted in situ [(DMTMM)] or isolated for further reaction.
[0029] In second step DMTMM salt in situ or in isolated form is reacted with compound of formula III which yields the formation of active ester of formula I.
(DMTMM) or DMTMM Formula III
Formula I-A
[0030] The active ester which is compound of formula I-A can be further isolated.
Formula I-A
In a similar way, in place of CDMT, 2-chloro-4,6-diphenyloxy-l,3,5-triazine, CDPT is used to produce 4-(4,6-diphenyloxy-l ,3,5-triazin-2-yl)-4- methylmorpholin-4-ium chloride, DPTMM, which further can be used to prepare following active ester of Formula I-B
Formula l-B
[0031] Further, apart from N-methylmorpholine, other bases can be used to produce corresponding salt which is equivalent to. DMTMM (4-(4,6-dimethoxy- l,3,5-triazin-2-yl)-4-methylmorpholin-4-iumchloride) or DPTMM (4-(4,6- diphenyloxy-l ,3,5-triazin-2-yl)-4-methylmorpholin-4-iumchloride). Such salts are further reacted with formula III compound to produce active esters.
The general scheme in which a base is used with CDMT or CDPT to produce various equivalents of DMTMM or DPTMM is as follows.
a, R',R" = OCH3
b, R',R" = OC6H5 where each of Ri, R2, R3 independently is hydrogen , alkyl, aryl, arylalkyl, cycloalkyl, heterocycloalkyl, heterocyclic groups or alternatively Rl s R2 and R3 together with Nitrogen or any two of the Ri, R2 and R3 together with Nitrogen form a ring which can be heterocycloalkyl, or heterocyclic and any such ring is optionally substituted by alkyl, aryl, arylalkyl, cycloalkyl, heterocycloalkyl, heterocyclic groups, nitro, halo, amino or substituted amino groups, or alternatively Ri, R2 and R3 together with Nitrogen form guanidine or substituted guanidine.
Isolation
[0032] The isolation and purification process of active esters would depend upon the solvents in which such active ester is prepared. The solvent is preferably aprotic and can be one selected from the group consisting of tetrahydrofuran (THF), dimethylformamide (DMF), toluene, 2-methyltetrahydrofuran, N-methyl- 2-pyrrolidone (NMP), and any combination thereof. Preferably solvent is dimethylformamide or tetrahydrofuran. When tetrahydrofuran is used as an aprotic solvent, the active ester prepared can be obtained by evaporating the solvent to obtain residue. The residue is further dissolved in another solvent, preferably aprotic such as ethyl acetate and purified to obtain pure active ester. When dimethylformamide is used as a solvent, first the active ester dissolved therein is precipitated by adding water. The precipitated active ester is dissolved in a solvent, preferably aprotic such as ethyl acetate and purified to obtain pure active ester.
Washings can be given before purification to remove unreacted materials.
Purity of active ester is usually about or greater than 95 %, preferably greater than
97 %.
Process for preparation of Anidulafungin from the active esters is as follows:
[0033] Further, the invention relates to the process for preparation of an antifungal agent Anidulafungin from novel active ester, formula I compound.
According to this aspect of the present invention, an antifungal agent, Anidulafungin, is prepared from the novel active ester (compound of formula II) wherein active ester prepared in situ is reacted with compound of formula IV (Echinocandin B) as follows:
Formula II
[0034] The active ester prepared in situ is reacted with Formula IV compound (Echinocandin B) in presence of a base. Isolated novel active ester can be similarly reacted with Formula IV compound (Echinocandin B) to produce Anidulafungin.
■ Formula II
Further, invention relates to process of preparing Aniduiafungin of Formula II from the active ester of formula I of the present invention. The process can be described in details as follows:
Process for preparation of an antifungal agent:
[0035] The process for the preparation of an antifungal agent comprises reacting the active ester of formula I with compound of formula IV (Echinocandin B) preferably in presence of a base selected from diisopropylethyl amine, N- methylmorpholine (NMM), pyridines, lutidines, picolines, dimethylaminopyridine, and collidines, and any combination thereof. The most preferred base diisopropylethyl amine.
[0036] Similar to above an active ester prepared from CDPT can produce DPTMM which can be further reacted with (4"-(pentyloxy)-[l ,l ':4', l "-terphenyl]- 4-carboxylic acid), a compound of formula III to produce active ester which can be acylated with compound of formula IV (Echinocandin B) to produce Anidulafungin as follows:
[0037] Apart from N-methylmorpholine, other bases can be used to prepare several equivalents of DMTMM or DPTMM and these equivalents are further reacted with the Echinocandin B, a compound of formula IV to produce Anidulafungin.
[0038] The DMTMM or DPTMM or their equivalents produced by using bases other than N-methylmorpholine can be isolated or reacted in situ with the Echinocandin B, a compound of formula IV to produce Anidulafungin.
The invention provides methods to prepare Anidulafungin using active esters of Formula I-A and I-B. The active esters are reacted either in situ or in isolated form. The active esters are obtained and isolated in pure form even in crude state. The purity is above 95 %. These esters are storage stable and can be stored up to or even more than one year at 2-8°C.
[0039] Alternatively, the process for preparation of Anidulafungin according to the present invention involves
a) reacting the compound of Formula IV in a solvent with the compound of
Formula I-A or Formula I-B in presence of a base
Formula 1-A whenR' and R"
Formula l-B when R' and R" b) isolating Anidulafungin and optionally purifying
[0040] In this process, solvent is selected from the group consisting of tetrahydrofuran (THF), dimethylformamide (DMF), Dimethylacetamide (DMA), toluene, 2-methyltetrahydrofuran, N-methyl-2-pyrrolidone (NMP), and any combination thereof and base is selected from the group consisting of diisopropylethylamine, N-methylmorpholine (NMM), pyridines, lutidines, picolines, dimethylaminopyridine, triethylamine and collidines, and any combination thereof.
[0041 ] In the above reaction, in a stirred solution of 4"-(pentyloxy)-[l ,l':4',l "- terphenyl]-4-carboxylic acid (compound of formula IV), CDMT or CDPT and
Echinocandin B in DMF is charged NMM at room temperature. The mixture is allowed to stir for overnight at room temperature. Alternatively, mixture is stirred overnight at higher temperatures such as 40°C or 60°C. Anidulafungin is isolated. The best purity product (Anidulafungin) is obtained when overnight stirring is conducted at room temperature.
The non-limiting examples according to present invention are as follows:
Examples
[0042] Example 1: Preparation of active ester
Method-I (DMTMM prepared in situ)
To a stirred solution of 4"-(pentyloxy)-[l ,l':4', '-terphenyl]-4-carboxylic acid (compound of formula III) (3.61 g, 10.0 mmol) in THF/DMF (150 mL) under N2 was charged CDMT (2.1 g, 12.0 mmol, 1.2 eq.) and continued stirring for 15 min at room temperature. Reaction mixture was cooled to 10-15 °C and NMM (1.65 mL, 1.5 eq.) charged slowly. The mixture was allowed to stir for overnight at room temperature.
Workup and purification:
THF method: Solvent was evaporated and residue dissolved in dichloromethane
/chloroform/ethyl acetate (30 volumes) and or other aprotic solvents. The mixture was filtered and the filtrate was washed with water and brine, dried over anhydrous sodium sulfate and evaporated to dryness by rotary evaporator.
DMF method: Reaction mixture was poured into ice water and the solid obtained was filtered, washed with hexane and dried under vacuum. The crude solid was redissolved in dichloromethane, undissolved compound was separated by filtration and washed successively with dichloromethane. Organic layer dried over anhydrous sodium sulfate and evaporated to dryness by rotary evaporator.
The crude product was further purified by flash column chromatography using dichloromethane as eluent.
Method-II (DMTMM in isolated form.)
To a stirred solution of 4"-(pentyloxy)-[l , Γ.·4', l "-te henyl]-4-carboxylic acid (formula III) (3.6 lg 10.0 mmol) in THF/DMF (150 mL) under N2 atmosphere, was charged DMTMM (1.5 eq.) and stir for 15 min at room temperature. Reaction mixture was cooled to 10-15 °C and DIPEA charged slowly. Reaction mixture was allowed to stir for overnight at room temperature.. Workup and purification has been carried as described earlier.
[0043] Example 2: Preparation of Anidulafungin
To a stirred solution of Echinocandin B represented by formula IV (0.798 g, 1 mmol) in DMF (10.0 mL) was charged active ester of formula I-A (1.1 eq.) and Diisopropylethylamine (1.5 eq.) at 5-10 °C. Reaction mixture was stirred for 3-4 h at 25 °C.
Workup: Reaction mixture was cooled to 5-10 °C and diethyl ether (20 vol) was charged slowly. Obtained white solid was filtered and washed successively with ether, dried under vacuum. Solid stirred with acetonitrile (5 vol.) for 15 min. at rt and filtered. Obtained solid dried under vacuum.
[0044] Example 3: Preparation of Anidulafungin (Active ester in situ)
To a stirred solution of 4"-(pentyloxy)-[l ,l ':4', l "-terphenyl]-4-carboxylic acid (compound of formula III) (3.97g, 1 1.0 mmol) in THF/DMF (150 mL) under N2 was charged CDMT (2.31 g, 13.2 mmol, 1.2 eq.) and NMM (1.81 mL, 16.5 mmol, 1.5 eq.) at 10 - 15 °C. The mixture was allowed to stir for overnight at room temperature. Upon confirmation of active ester formation by HPLC, Echinocandin B (7.98 g, 10 mmol) in DMF (10 mL) and diisopropylethylamine (10 mmol) were added and continued stirring for 3-4 h. The reaction mixture was filtered, the filtrate was cooled 5-10 °C and cold diethyl ether was charged slowly. The precipitated white solid was filtered and washed successively with ether, dried under vacuum. Solid stirred with acetonitrile (5 vol.) for 15 min. at rt and filtered. Obtained solid dried under vacuum.
(Yield 80%, HPLC purity 97%) -
[0045] Example 4: Preparation of Anidulafungin (Active ester in situ)
To a stirred solution of 4"-(pentyloxy)-[l ,l':4',l"-terphenyl]-4-carboxylic acid (compound of formula IV) (3.97g, 1 1.0 mmol) in THF/DMF (150 mL) under N2 was charged CDMT (2.31 g, 13.2 mmol, 1.2 eq.) and NMM (1.81 mL, 16.5 mmol, 1.5 eq.) at 10 - 15 °C. The mixture was allowed to stir for overnight at room temperature. Upon confirmation of active ester formation by HPLC, Echinocandin B (7.98 g, 10 mmol) and diisopropylethylamine (10 mmol) were added and continued stirring for 3-4 h. The reaction mixture was filtered, the filtrate was cooled 5-10 °C and cold diethyl ether was charged slowly. The precipitated white solid was filtered and washed successively with ether and suck dried. Solid obtained was stirred with process water (5 vol.) and filtered. Obtained solid stirred with acetonitrile (5 vol.) for 15 min. at RT and filtered and dried under vacuum. (Yield 75%, HPLC purity 98%)
[0046] Example 5: Preparation of Anidulafungin
To a stirred solution of 4"-(pentyloxy)-[l,r:4',r'-teiphenyl]-4-carboxylic acid (compound of formula IV) (4.52 g, 12.53 mmol), CDMT (2.64 g, 15 mmol, 1.2 eq.) and Echinocandin B (10 g, 12.53 mmol) in DMF (500 mL) was charged NMM (2.81 mL, 25 mmol, 2 eq.) at RT. The mixture was allowed to stir for overnight at room temperature. The reaction mixture was filtered, the filtrate was charged slowly in diethyl ether. The precipitated white solid was filtered and washed successively with ether and suck dried. Solid obtained was stirred with process water (5 vol.) and filtered. Obtained solid stirred with acetonitrile (5 vol.) for 15 min. at RT and filtered and dried under vacuum. (Yield 80%, HPLC purity 99.10%).
[0047] Example 6: Preparation of Anidulafungin
To a stirred solution of 4"-(pentyloxy)-[l,l':4',l "-terphenyl]-4-carboxylic acid (compound of formula IV) (4.52 g, 12.53 mmol), CDMT (2.64 g, 15 mmol, 1.2 eq.) and Echinocandin B (10 g, 12.53 mmol) in DMF (500 mL) was charged NMM (2.81 mL, 25 mmol, 2 eq.) at RT. The mixture was allowed to stir for overnight at room temperature 40 °C. The reaction mixture was filtered, the filtrate was charged slowly in diethyl ether. The precipitated white solid was filtered and washed successively with ether and suck dried. Solid obtained was stirred with process water (5 vol.) and filtered. Obtained solid stirred with acetonitrile (5 vol.) for 15 min. at RT and filtered and dried under vacuum. (Yield 75%, HPLC purity 94%).
[0048] Example 7: Preparation of Anidulafungin
To a stirred solution of 4"-(pentyloxy)-[l, :4', l "-terphenyl]-4-carboxylic acid (compound of formula IV) (4.52 g, 12.53 mmol), CDMT (2.64 g, 15 mmol, 1.2 eq.) and Echinocandin B (10 g, 12.53 mmol) in DMF (500 mL) was charged NMM (2.81 mL, 25 mmol, 2 eq.) at RT. The mixture was allowed to stir for overnight at room temperature 60 °C. The reaction mixture was filtered, the filtrate was charged slowly in diethyl ether. The precipitated white solid was filtered and washed successively with ether and suck dried. Solid obtained was stirred with process water (5 vol.) and filtered. Obtained solid stirred with acetonitrile (5 vol.) for 15 min. at RT and filtered and dried under vacuum.
(Yield 80%, HPLC purity 90%).

Claims

We claim
1. Active esters of formula I-A and formula I-B
Formula l-A whenR' and R"
Formula l-B when R' and R"
2. The active esters according to claim 1 having purity greater than or equal to
95 %.
3. Active esters of claim 1 which can be stored for at least 1 month at 2-8°C before converting into Anidulafungin.
4. Process of preparing active esters of formula I-A and I-B comprising a. Reacting either 2-chloro-4,6-dimethoxy triazine (CDMT) or its derivative or 2-chloro-4,6-diphenyloxy triazine (CDPT) or its derivative with 4"- (pentyloxy)-[l ,l ':4',l "-terphenyl]-4-carboxylic acid (Formula III compound) in an aprotic solvent and in presence of a base.
Formula III
b. O tionally isolatin active ester of formula I-A or I-B
Formula I-A whenR' and R"
Formula I-B when R' and R"
5. Process of preparing Anidulafungin comprising following steps
a. Preparing active ester of Formula I-A or Formula I-B
Formula l-A whenR' and R" = CH3
Formula l-B when R' and R" = C6H5
Optionally isolating active ester
Reacting active ester of formula I-A or formula I-B with Echinocandin B (Formula IV compound) to produce Anidulafungin.
EchinocandinB /Formula IV compound
6. The process of preparing Anidulafungin according to claim 5 wherein in the first step active ester is prepared by reacting either 2-chloro-4,6-dimethoxy triazine (CDMT) or its derivative or 2-chloro-4,6-diphenyloxy triazine (CDPT) or its derivative with 4"-(pentyloxy)-[l ,Γ:4',l"-te henyl]-4-carboxylic acid (Formula III compound) in an aprotic solvent and in presence of a base.
7. The process according to claim 6 wherein the base used in the preparation of the active ester is N-methylmorpholine (NMM) and the derivative of 2-chloro- 4,6-dimethoxy triazine is 4-(4,6-dimethoxy- 1 ,3,5 -triazin-2-yl)-4- methylmorpholin-4-iumchloride and derivative of 2-chloro-4,6-diphenyloxy triazine is 4-(4,6- diphenyloxy-l ,3,5-triazin-2-yl)-4-methylmo holin-4- iumchloride
8. The process according to claim 6 wherein aprotic solvent is selected from the group consisting of tetrahydrofuran (THF), dimethylformamide (DMF), dimethylacetamide, toluene, 2-methyltetrahydrofuran, N-methyl-2-pyrrolidone (NMP), and any combination thereof.
9. A process for preparation of Anidulafungin comprising the steps of
b) reacting the compound of Formula IV in a solvent with the compound of Formula I-A or Formula I-B in presence of a base
Formula IV
Formula l-A whenR' and R" = CH3
Formula l-B when R' and R" = C6H5
a) isolating Anidulafungin and optionally purifying
10. Process of preparing Anidulafungin according to claim 9 wherein solvent is selected from the group consisting of tetrahydrofuran (THF), dimethylformamide (DMF), Dimethylacetamide (DMA), toluene, 2- methyltetrahydrofuran, N-methyl-2-pyrrolidone (NMP), and any combination thereof and base is selected from the group consisting of diisopropylethylamine, N-methylmorpholine (NMM), pyridines, lutidines, picolines, dimethylaminopyridine, triethylamine and collidines, and combination thereof.
EP15849205.8A 2014-10-07 2015-10-07 Intermediates and processes to prepare anidulafungin Withdrawn EP3464319A4 (en)

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