MXPA98004665A - Derivatives of 1,3-oxazin-4-ona as herbici - Google Patents

Abstract

1,3-Oxazin-4-one derivatives of formula (I) are provided wherein Q represents -C (= O) -, -CH (OH) -o-C (OR11) (OR11) -, in which R11 represents lower alkyl, or the two groups -OR11 together with the carbon atom to which they are attached, form a cyclic ketal group of 5-6 members, and their use as a herbicide

Description

DERIVATIVES OF 1,3-OXAZ --- N-4-ON? AS HERBICIDES DESCRIPTION OF THE INVENTION This invention relates to novel derivatives of 1,3-oxazin-4-one, with herbicidal compositions containing the same, and with novel intermediates to prepare them. Certain types of 1,3-oxazin-4-one derivatives, such as 2,3-dihydro-6-methyl-3- (1-methyl-1-phenylethyl) -5-phenyl-4H-1, 3-oxazin -4-one and its herbicidal activity, is described in, for example, International Patent Publication No. WO 93/15064. However, the compounds described in the aforementioned publication do not have a ketone or alcohol functionality in the group attached to the nitrogen atom in the 3-position of a 1,3-oxazine ring. In accordance with the present invention, 1, 3-oxazin-4-one derivatives of formula I are provided: REF: 27583 wherein R1 represents phenyl optionally substituted by one to five groups which may be the same or different, which are selected from halogen, hydroxy, lower alkyl, lower haloalkyl, lower alkoxy, lower haloalkoxy, -S (0) nR7 , -C02R7, -COR7, cyano, nitro, -O (CH2) qC02R7 and phenoxy; a five to seven member heteroaromatic ring having from one to four heteroatoms in the ring which may be the same or different which are selected from nitrogen, oxygen and sulfur, the ring may optionally be substituted by one to four groups which may be the same or different, which are selected from halogen, hydroxy, lower alkyl, lower haloalkyl, lower alkoxy, lower haloalkoxy, -S (0) nR7, -C02R7, -COR7, cyano, nitro, -O (CH2) qC02R7 and phenoxy; or an optionally halogenated straight or branched chain alkyl, alkenyl or alkynyl group containing up to ten carbon atoms; R2 represents: a hydrogen atom; or a straight or branched chain alkyl group containing from one to ten carbon atoms which is optionally substituted by one or more R8 groups which may be the same or different; a linear or branched, optionally halogenated alkenyl or alkynyl group having up to ten carbon atoms; or a group that is selected from cyano, -CHO, -COR7. -C02H, -C02R7, -COSR7, -CONR9R10, -CH = NOH, -CH = NOR7, -CH = NOCOR7, -CH = R9R10, -CH2CN, -CH2N02 and oxiranyl; R3 represents - (CH2) r- (phenyl or naphthyl optionally substituted by one to five groups which may be the same or different which are selected from halogen, hydroxy, lower alkyl, lower haloalkyl, lower alkoxy, lower haloalkoxy, -S (0 ) nR6, -C02R6, -COR6, cyano, nitro, -O (CH2) qC02Rs, phenoxy and -SF5); - (CH2) g- (five to seven membered heteroaromatic ring having from one to four ring heteroatoms which may be the same or different, which are selected from nitrogen, oxygen and sulfur, the ring is optionally fused to a ring phenyl or a second aromatic ring of five to seven members having one to four heteroatoms which may be the same or different which are selected from nitrogen, oxygen and sulfur, to form a bicyclic ring system, the monocyclic ring or any ring in the bicyclic system is optionally substituted by one to four groups which may be the same or different, which are selected from halogen, hydroxy, lower alkyl, lower haloalkyl, lower alkoxy, lower haloalkoxy, -S (0) nR6, -C02R6, - COR6, cyano, nitro, -O (CH2) qC02R6, and phenoxy); an optionally halogenated straight or branched chain alkyl, alkenyl or alkynyl group containing up to ten carbon atoms; an optionally halogenated straight or branched chain alkyl, alkenyl or alkynyl group of up to ten carbon atoms which is substituted by cycloalkyl containing from three to six carbon atoms; or cycloalkyl containing from three to six carbon atoms or cycloalkenyl containing five to six carbon atoms, ring systems which are optionally substituted by a group R6 or one or more halogen atoms, which may be the same or different; R4 and R5 independently represent lower alkyl; R6 and R7 independently represent lower alkyl or lower haloalkyl; n represents zero, one or two; q represents one or two; r represents zero, one or two, s represents zero or one; R8 is halogen, -OH, -OR7, -OCOR7, -S (0) nR7, -NR9R10 or azide; R9 and R10 independently represent hydrogen, lower alkyl or lower haloalkyl; Q represents -C (= 0) -, -CH (OH) - or -C (OR1: L) (OR11); wherein R 11 represents lower alkyl; or the two groups -OR11, together with the carbon atom to which they are attached, form a cyclic ketal group of five or six members; and agriculturally acceptable salts thereof, which possess useful properties. By the term "agriculturally acceptable salts" is meant salts, cations or anions of which are known and accepted in the art for the formation of salts for agricultural or horticultural use. Preferably, the salts are soluble in water.

Suitable salts with bases include alkali metal salts (for example sodium and potassium) of alkaline earth metal (for example calcium and magnesium) ammonium and amine (for example diethanolamine, triethanolamine, octylamine, morpholine and dioctylmethylamine). Suitable acid addition salts, for example, those formed by compounds of formula I containing an amino group, include salts with inorganic acids, for example hydrochlorides, sulphates, phosphates and nitrates, and salts with organic acids, for example acetic acid .

In certain cases, the groups R1 to R11 can give rise to stereoisomers and geometric isomers. All of such forms are encompassed by the present invention. In the description, unless otherwise specified, the following terms are generally defined as follows: "lower alkyl" means a straight or branched chain alkyl group having one to six carbon atoms; "lower haloalkyl" means a straight or branched chain alkyl group having one to six carbon atoms, substituted by one or more halogens; "lower alkoxy" means a straight or branched chain alkoxy group having one to six carbon atoms; "lower haloalkoxy" means a straight or branched chain alkoxy group having one to six carbon atoms, substituted by one or more halogens; "halogen" means a fluorine, chlorine, bromine or iodine atom. In the description that follows, several preferred classes (due to their herbicidal properties) of compounds of formula I above are described. Preferred are compounds of formula (I) in which R3 is - (CH2) R- (phenyl optionally substituted by one to five groups which may be the same or different which are selected from halogen, hydroxy, lower alkyl, lower haloalkyl, lower alkoxy, lower haloalkoxy, -S (0) nR6, -C02R6, -COR6, cyano, nitro, -O (CH2) qC02R6, and phenoxy); - (CH2) s- (five to seven membered heteroaromatic ring having from one to four ring heteroatoms which may be the same or different, which are selected from nitrogen, oxygen and sulfur, the ring is optionally fused to a ring phenyl or a second five to seven membered heteroaromatic ring having from one to four heteroatoms which may be the same or different which are selected from nitrogen, oxygen and sulfur, to form a bicyclic ring system, the monocyclic ring or any ring in the bicyclic system is optionally substituted by one to four groups which may be the same or different, which are selected from halogen, hydroxy, lower alkyl, lower haloalkyl, lower alkoxy, lower haloalkoxy, -S (0) nR6, -C02R6, - COR6, cyano, nitro, -O (CH2) qC02R6, and phenoxy); or an optionally halogenated straight or branched chain alkyl, alkenyl or alkynyl group containing up to ten carbon atoms; or cycloalkyl containing from three to six carbon atoms which optionally are substituted by a group R6 or one or more halogen atoms, which may be the same or different; R is zero or one; and R8 is not azide. Preferred are compounds of formula (I) above in which R 1 represents phenyl or thienyl optionally substituted by one or more groups which are selected from halogen, lower alkyl and lower haloalkyl. More preferably, R1 represents phenyl. A further preferred class of compounds of formula I above are those wherein R 2 represents a straight or branched chain alkyl group having from one to six carbon atoms, more preferably methyl. Especially preferred are compounds of formula (I) above in which R 4 and R 5 each represent methyl. Especially preferred are compounds of formula (I) above, in which Q represents -C (= 0) -, due to its herbicidal activity. The compounds of formula (I) above, in which Q is -CH (OH) - generally have a lower level of herbicidal activity to which corresponds to compounds of formula (I) in which Q is -C (= 0) -, and are also useful as intermediates in the preparation of such compounds.

Preferred are compounds of formula (I) above in which R3 is cyclopentyl because of its high activity against weeds found in rice. Also preferred are compounds of formula (I) above in which R3 is n-butyl or butenyl (e.g. 3 - . 3 -butenyl) due to its effectiveness against difficult-to-control weeds found in cereals, such as alopecuro (Alopecurus myosuroides). A particularly preferred class of compounds of formula (I) above are those in which: R 1 represents phenyl optionally substituted by halogen; R2, R4 and R5 each represent methyl; Q represents -C (= 0) -; and R3 represents: - (CH2) r- (phenyl optionally substituted by one or two groups which are selected from halogen and an optionally halogenated alkyl group containing one or two carbon atoms); or a straight or branched chain alkyl, alkenyl or alkynyl group containing up to four carbon atoms; and r is zero or one. A particularly preferred additional class of compounds of formula (I) above are those in which: R1 represents: phenyl or thienyl optionally substituted by halogen or methyl; each of R2, R4 and R5 represents methyl; Q represents -C (= 0) -, - R3 represents - (CH2) r- (phenyl optionally substituted by one or two groups which are selected from halogen or an optionally halogenated alkyl group containing one or two carbon atoms); a straight or branched chain alkyl or alkenyl group containing up to six carbon atoms; or cycloalkyl containing from three to six carbon atoms; and r is zero or one. A particularly preferred additional class of compounds of formula (I) above are those having one or more of the following characteristics. R1 represents: phenyl or thienyl optionally substituted by halogen or methoxy; each of R2, R4 and R5 represents methyl; Q represents -C (= 0) -; R3 represents: - (CH2) r- (phenyl group optionally substituted by one or two groups which are selected from halogen or methyl); thienyl, furyl, benzothiazolyl or pyridyl, optionally substituted by halogen or methyl (optionally halogenated); an optionally halogenated straight or branched chain alkyl, alkenyl or alkynyl group containing up to eight carbon atoms; or cycloalkyl containing from three to six carbon atoms; and r is zero or one. The following compounds of formula (I) above, in which R 4 and R 5 are methyl and Q is -C (= 0) - form part of the present invention. In the following table "Ph" means phenyl, "Me" means methyl, "Et" means ethyl, "Pr" means propyl and "Bu" means butyl. When the subscripts are omitted after the atoms, it will be understood that they are implicit, for example CH = CH2 means -CH = CH2, etc.

Compound Rl R2 R3 No. 1 Ph Me i-Pr 2 Ph Me n-Bu 3 Ph Me 3.5-F2 Ph 4 Ph Me 2-F-5-CF3 phenyl Ph Me 3-Cl benzyl 6 Ph Me 3-CF 3 benzyl 7 Ph Me CH 2 CH = CH 2 8 Ph Me CH = CH 2 9 2-F phenyl Me 4 -F phenyl 10 Ph Me Ethinyl 11 2-F phenyl Me 2 -Me phenyl 12 2-F phenyl Me 4-F-3-Me phenyl 13 Ph Me 2-Me phenyl 14 Ph Me 4-F phenyl 15 Ph Me 4-F-3-Mephenyl 16 Ph Me Ph 17 Ph Me 2-Cl phenyl 18 Ph Me 3-Cl phenyl 19 Ph Me 4-C1 phenyl 20 Ph Me 3-CF3 phenyl 21 Ph Me 3.5-C12 phenyl 22 Ph Me 2.5-F2 phenyl 23 Ph Me 2-pyridyl 24 Ph Me 4-pyridyl 25 Ph Me 4-methylthiazol-2-yl 26 Ph Me 5-chlorothiazol-2-yl 27 Ph Me Me 28 Ph Me Et 29 Ph Me n-Pr 30 Ph Me i-Bu 31 Ph Me Cyclopropyl 32 Ph Me Sec-butyl 33 Ph Me Cyclobutyl 34 Ph Me n-pentyl 35 Ph Me n-hexyl 36 Ph Me Ciciohexyl 37 Ph Me n-heptyl 38 Ph Me n-octyl 39 Ph Me 3,5-Cl2 Benzyl 40 2- F phenyl Me 3.5-C12 phenyl 41 2-F phenyl Me 3-CF 3 phenyl 42 2-F phenyl Me 4-methylthiazol-2-yl 43 2-F phenyl Me n-butyl 44 2-F phenyl Me Cyclobutyl 45 2 -F phenyl Me 3-Cl benzyl 46 2-OMe phenyl Me 3,5-Cl 2 phenyl 47 2-OMe phenyl Me 3-CF 3 phenyl 48 2-OMe phenyl Me n-butyl 49 2-OMe phenyl Me n-propyl 50 2 -OMe phenyl Me 2-pyridyl 51 3-Cl phenyl Me n-butyl 52 3-Cl phenyl Me 3-5-C12 phenyl 53 2-thienyl Me 3, 5-C12 phenyl 54 2-thienyl Me 3-CF 3 phenyl 55 2-thienyl Me 4-methylthiazol-2-yl 56 2-thienyl Me n-butyl 57 2-thienyl Me Cyclobutyl 58 2-thienyl Me 3-Cl benzyl 59 2-furyl Me 3.5-C12 phenyl 60 Iso-butyl Me 3,5-Cl 2 phenyl 61 Iso-butyl Me n-butyl 62 Iso-butyl Me 3-Cl benzyl 63 4-methylpent-l-in-l-yl Me 3 -CF3 phenyl 64 4-methylpent-l-in-l-yl Me n -butyl 65 4-methylpent-l-ln-l-yl Me 4-pyridyl 66 4-methylpen Me Ethyl 67 2-methylpro Me 3,5C12phenyl 68 2-methylpro Me N-butyl 69 Ph CH2F 3,5-C12 phenyl 70 Ph CH2F n-butyl 71 Ph CH2F 3-Cl benzyl 72 Ph CH2F 5-chlorothiazol-2-yl 73 Ph CH20Me 3-CF3 phenyl 74 Ph CH20Me Iso-butyl 75 Ph CH20Me 3-5-C12 benzyl 76 Ph CH20Me Cycloexil 77 Ph CH2SMe 2,5-C12 phenyl 78 Ph CH20SMe n-butyl 79 Ph CH20SMe 3-Cl benzyl 80 Ph CH20SMe 5-chlorothiazole-2-xlo 81 Ph CHF2 3-CF3 phenyl 82 Ph CHF2 Iso-butyl 83 Ph CHF2 3,5-C12 benzyl 84 Ph CHF2 Cycloexil 85 Ph CH = N0Me 3,5-C12 phenyl 86 Ph CH = N0Me n-butyl 87 2-F phenyl CH2SMe 3,5-C12 phenyl 88 2-F phenyl CH20Me n-butyl 89 2-thienyl CH2F 3,5-Cl2 phenyl 90 Ph ME t-Bu 91 Ph Me 2-thienyl 92 Ph Me -furyl 93 Ph Me 2-benzthiazolyl 94 Ph Me 3,4-C12 benzyl 95 Ph Me 3.5-Me2-benzyl 96 Ph Me 4-Cl-benzyl 97 Ph Me Cyclopentyl 98 Ph Me 3-Me-benzyl 99 Ph Me Benzyl 100 Ph Me 3, 5-F2-benzyl 101 Ph Me 6-Me-2 -pyridyl 102 Ph Me - (CH2) 2CH (Me) 2 103 Ph Me 4-CF3 -2-pyridyl 104 Ph Me 2, 5-F2-benzyl 105 Ph Me 2-Cl-benzyl 106 Ph Me 2, 4-F2 -benzyl 107 Ph Me 4-F-benzyl 108 Ph Me - (CH2) 2CH = CH2 109 Ph Me -CH (Me) CH2CH2Me 110 2-F Ph Me -CH2CH2 = CHMe 111 2-F Ph Me n-pr 112 2 -OMe Ph Me n-pr 113 2 -OMe Ph Me - (CH2) 2Ch = CH2 114 Ph Me Ciciohexilo 115 Ph Me -CH2CH (Me) CH Me 116 Ph Me - (CH2) 2CMe3 117 Ph Me -CH (CH2Me) 2 118 Ph Me -CH2CMe3 119 2-thienyl Me - (CH2) 2CH = CH2 120 2 -thienyl Me Cyclopentyl 121 Ph Me - (CH2) 3CF3 122 Ph Me 3-butinyl 123 Ph Me - (CH2) 2CH (Me) CH2Me 124 2-F Ph Me Cyclopentyl 125 2-Cl Ph Me Cyclopentyl 126 2 -Me Ph Me Cyclopentyl 127 2-Br ph Me Cyclopentyl 128 4-F Ph Me Cyclopentyl 129 2-F Ph Me 3-butynyl 130 2-Cl Ph Me 3-butynyl 131 2-Me Ph Me 3-butynyl 132 2Be Ph Me 3-butynyl 133 4-F Ph Me 3-butynyl 134 2 -thienyl Me 3- butynyl 135 2-Cl Ph Me n-butyl 136 2 -Me Ph Me n-butyl 137 2-Br Ph Me n-butyl 138 4-F Ph Me n-butyl 139 Ph Me Cyclopent-1-enyl 140 Ph Me Ciclopent-2 -enyl 141 Ph Me cyclopropylmethyl 142 Ph Me cyclobutylmethyl 143 Ph Me cyclopentimethyl 144 Ph Me - (CH2) 2 (3_C1 Ph) 145 Ph Me - (CH2) 2 (4-OMe Ph) 146 Ph Me - (CH2) 2 (3,5-Cl2 Ph) 147 Ph Me - (CH2) 2 (3,5-F2 Ph) 148 Ph Me - (CH2) 2 (4-F Ph) 149 Ph Me - (CH2) 2 (2 -Me Ph) 150 Ph Me - (CH2) 2 (3CF3 PH) 151 Ph Me - (CH2) 2 (2.5-F2 Ph 152 2-F Ph Me - (CH2) 2CH = CH2 153 2 -Me Ph Me - (CH2) 2CH = CH2 154 2-Br Ph Me - (CH2) 2CH = CH2 155 2-Cl Ph Me - (CH2) 2CH = CH2 156 Ph CH2F - (CH2) 2CH = CH2 157 Ph CH2OMe - (CH) 2CH = CH2 158 Ph CH2SMe - (CH2) 2CH = CH2 159 Ph CH2N3 - (CH2) 2CH = CH2 160 Ph Me CH2-cyclopropyl 161 Ph Me CH2-cyclobutyl 162 Ph Me CH2-cyclopentyl 163 Ph Me (CH2) 2 (4-C1 Ph) 164 Ph Me CH2C (Me) 2CH = CH2 165 Ph Me CH2C (Me) 2CH = CH2 166 2-F Ph Me CH2-cyclopropyl 167 2-F Ph Me CH2-cyclobutyl 168 2-F Ph Me CH2-cyclopentyl 169 2-F Ph Me (CH2) 2 (4-C1 Ph) 170 2-F Ph Me CH2C (Me) 2CH = CH2 171 2-F Ph Me CH2C (Me) 2CH = CH2 172 2-thienyl Me CH2-cyclopropyl 173 2-thienyl Me CH2-cyclobutyl 174 2-thienyl Me CH2-cyclopentyl 175 2 -thienyl Me (CH2) 2 (4-C1 Ph 176 2 -thienyl Me CH2C (Me) 2CH = CH2 177 2-thienyl Me CH2C (Me) 2CH = CH2 178 Ph CH20Me CH2-cyclopropyl 179 Ph CH2F Ch2-cyclopentyl 180 Ph CH2F cyclopentyl 181 Ph CH20Me Cyclopentyl 182 Ph CH20et Cyclopentyl 183 Ph CHSMe Cyclopentyl 184 Ph CHF2 Cyclopentyl 185 Ph CH = NOMe Cyclopentyl 186 Ph CH2N3 Cyclopentyl 187 2-F Ph CH2F Cyclopentyl 188 2-F Ph CH20Me Cyclopentyl 189 2-F Ph CH20et Cyclopentyl 190 2- F Ph CH2Sme cyclopentyl 191 2-F Ph CHF2 cyclopentyl 192 2-F Ph CH = NOMe cyclopentyl 193 2-F Ph CHCH2N3 cyclopentyl 194 2-thienyl CH2F cyclopentyl 195 2-thienyl CHOMe cyclopentyl 196 2 -thienyl CH20Et cyclopentyl 197 2-thienyl CH2SMe cyclopentyl 198 2-thienyl CHF2 cyclopentyl 199 2-thienyl CH = MONe cyclopentyl 200 2 -thienyl CH2N3 cyclopentyl 201 Ph Me 3-OMe-5-Cl Ph 202 2-F Ph Me 3-OMe-5-Cl Ph 203 2 -thienyl Me 3-0Me-5-Cl ph 204 2Me Ph Me 3-OMe-5-Cl Ph 205 2-Br Ph Me 3 -OMe- 5- Cl Ph 206 2-Cl Ph Me 3 -OMe-5- Cl Ph 207 4-F Ph Me 3-0Me-5-Cl Ph The numbers 1 to 207 are assigned to these compounds for reference and subsequent identification: Particularly preferred are the following compounds of formula (I): 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2, 4- dimethylpentan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methylheptan-3-one; 1- (3, 5-difluorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methylpropan-1- ona; 1- (2-fluoro-5-trifluoromethylphenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan- 1-one; 1- (3-chlorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -3-methylbutan-2-one; 1- (3-trifluoromethylphenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -3-methylbutan-2-one; 2- (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methylhex-5-en-3-one; 4- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -4-methylpent-1-en-3-one; 1- (4-f luorofenyl) -2- [5- (2-f luorofenyl) -2,3-dihydro-6-methyl-4-oxo-4H-l, 3-oxazin-3-yl) - 2-met ilpropan-1-one; 4- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-1,3-oxazin-3-yl) -4-methylpent-1-yn-3-one 2- [5 - (2-fluorophenyl) -2,3-dihydro-6-methyl-4-oxo-4H-1,3-oxazin-3-yl] -1- (2-methylphenyl-2-methylpropan-1-one; - (4-Fluoro-3-methylphenyl) -2- [5- (2-fluorophenyl) -2,3-dihydro-6-methyl-4-oxo-4H-l, 3-oxazin-3-yl) -2 -methylpropan-1-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methyl-1- (2-methylphenyl) propan-1-one; 1- (4-fluorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-l-one; 1- (4-fluoro-3-methylphenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan- 1-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methyl-1-phenylpropan-1-one; 1- (2-chlorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-l-one; 1- (3-chlorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-l-one; 1- (2-chlorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-1-one; 1- (3-trifluoromethylphenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-1-one; 1- (3, 5-dichlorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-1- ona; 3 - . 3 - (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -3-methylbutan-2-one; 2- (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -3-methylhexan-2-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2,5-dimethylhexan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpentan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3 • oxazin-3-yl) -2-methylundencan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2,4-dimethylhexan-3-one; 1-cyclopropyl -2 - (2,3-dihydro-6-methyl-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-l-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2,4, 4-trimethylpentan-3-one; 2- (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methyl-1- (2-thienyl) propan-1-one; 2 - (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -1- (3-furyl) -2-methylpropan-1-one; 1- (2-benzothiazole) -2- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -2-met-ilpropan-1 -one; 1- (3,4-dichlorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-f-4H-1,3-oxazin-3-yl) -3-methylbutan-2 -one; 1- (3,5-dichlorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-f-4H-l, 3-oxazin-3-yl) -3-methylbutan-2 -one, - 3- (2,3-dihydro-6-methyl-oxo-5-phenyl-4H-1,3-oxazin-3-yl) - (3,5-dimethylphenyl) -3-methylbutan-2 -one; 1- (4-chlorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -3-methylbutan-2-one; l-cyclopentyl-2- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -2-met-ilpropan-1-one; 3 - (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-1, 3-oxazin-3-yl) -3-methyl) -1- (3-methylphenyl) butan- 2-one; 2- (2, 3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -2-methylnonan-3-one; 2- (2,3-Dihydro-6-methyl-4-oxo-5-f-enyl-4H-1, 3-oxazin-3-yl) -2-methyloctane-3-one; 3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -3-methyl-1- (f-enyl) -butan-2-one; 1- (3, 5 -dif luorofenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methylbutan- 2-one; 2- (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -2-methyl-1- (6-methylpyrid-2-yl) propan -1-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2,6-dimethylheptan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -2-methyl-1- (4-trifluoromethyl-pyrid-2-yl) propan -l-ona; 1- (2, 5-difluorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methylbutan-2- ona; 1- (2-chlorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -3-methylbutan-2-one; 1- (2,4-difluorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methylbutan-2- ona; 1- (4-fluorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methylbutan-2-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4 H -1,3-oxazin-3-yl) -2-methylhept-6-en-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2,4-dimethylheptan-3-one; 2- [2,3-dihydro-5- (2-f luorofenyl) -6-methyl-4-oxo-4 H -1,3-oxazin-3-yl] -2-methylheptan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -3-methylhept-5-en-3-one; 2- [2,3-dihydro-5- (2-f luorofenyl) -6-methyl-4-oxo-4 H -1,3-oxazin-3-yl] -2-methylhexan-3-one; 2- [2,3-dihydro-5- (2-methoxyphenyl) -6-methyl-4-oxo-4 H -1,3-oxazin-3-yl] -2-methylhexan-3-one; 2- [2,3-dihydro-5- (2-methoxyphenyl) -6-methyl-4-oxo-4 H -1,3-oxazin-3-yl] -2-methylheptan-3-one; 2- [2,3-dihydro-5- (2-methoxyphenyl) -6-methyl-4-oxo-4H-1, 3-oxazin-3-yl] -2-methylhept-6-en-3-one; l-cyclohexyl-2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl] -2-methylpropan-1-one; 2- [2 , 3-dihydro-6-methyl-4-oxo-5- (2-thienyl) -4H-1,3-oxazin-3-yl] -2-methylhexan-3-one; 2- [2,3-dihydro] -6-methyl-4-oxo-5- (2-thienyl) -4H-1,3-oxazin-3-yl] -2-methylheptan-3-one; 2- (2,3-dihydro- 6 - methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl] -2,5-dimethylheptan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo- 5-phenyl-4H-1,3-oxazin-3-yl] -2,6,6-trimethylheptan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl- 4H-1, 3-oxazin-3-yl] -4-ethyl-2-methylhexan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl] -2,5, 5-trimethylhexan-3-one; 2- [2, 3-dihydro-6-methyl-4-oxo-5- (2-thienyl) -4H-1, 3-oxazin-3-yl] -2-methylhept-6-en-3 -one; 1-cyclopentyl-2- [2, 3-dihydro-6-methyl-4 -oxo-5- (2-thienyl) - 4H-1, 3-oxazin-3-yl] -2-methylpropan-l-one; l-cyclobutyl-2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl] -2-methylpropan-1-one; 2 - (2,3-dihydro-6-methyl-4-oxo-5-phenyl) -4H-1, 3-oxazin-3-yl] -2-methyl-7,7,7-trifluoroheptan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-phenyl-4H-1, 3-oxazin-3-yl] -2,6-dimethyloctane-3-one; and 2- (2, 3 - dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl] -2-methylhept-6-yn-3-one The compounds of formula (I) above can be prepared by the application or adaptation of known methods (ie, methods used hitherto or described in the literature) It should be understood that in the descriptions of the following processes, the sequences may be performed in different orders and that appropriate protective groups may be required to obtain the compounds that are sought In accordance with a feature of the present invention, compounds of formula (I) in which Q represents a group -C (= 0) - can be prepared by oxidation of the corresponding compound of formula (I) wherein Q represents a group -CH (OH) - The oxidation is generally carried out with a suitable oxidizing agent, for example, chromic acid or pyridinium chlorochromate. it can be carried out in a suitable solvent, for example ether or dichloromethane and at a temperature from 0 ° C to the reflux temperature of the solvent. According to a further feature of the present invention, compounds of formula (I) wherein Q represents -CH (OH) - can be prepared by the reaction of an aldehyde of the formula (II): wherein R1, R2, R4 and R5 are as defined above, with an organometallic compound of formula R3-M, wherein R3 is as defined above and M represents a metal group, preferably a group of magnesium bromide or a lithium atom. Generally, the reaction is carried out in an inert solvent, for example ether and tetrahydrofuran and at a temperature from -78 ° C to the reflux temperature of the solvent. According to a further feature of the present invention, it is possible to prepare the compounds of formula (I) in which Q represents -C (0R13-) (OR11) -, by reaction of a compound of formula (I) in which Q represents -C (= 0) -, with an alcohol of formula R1: L-OH. Generally the reaction is carried out in the presence of an acid catalyst, for example 4-toluenesulfonic acid, and an inert solvent, for example toluene, and at a temperature from 60 ° C to the reflux temperature of the solvent. The reaction is facilitated by removal of the water formed preferably by azeotropic distillation or in the presence of a dehydrating agent, for example a molecular sieve. Intermediates of formula (II) can be prepared by the reduction of an ester of formula (III): i: wherein R represents an alkyl group, preferably ethyl. The reaction is generally carried out using a suitable reducing agent, for example lithium aluminum hydride, in an inert solvent, for example tetrahydrofuran, at a temperature from -80 ° C to 20 ° C. The esters of formula (III) can be prepared by the reaction of a compound of formula (IV): (IV) wherein R1 and R2 are as defined above, with an imine of formula CH2 = N-C (R4) (R5) C02R wherein R4, R5 and R are as defined above. Generally the reaction is carried out in the presence or absence of solvent and at a temperature from 90 ° C to 200 ° C or the boiling point of the solvent. When solvent is used it is inert, for example xylene, and the acetone produced is preferably removed by distillation. The compounds of formula (IV) are known or can be prepared by the application or adaptation of known methods. The compounds of formula (I) above can be prepared by interconversion of other compounds of formula (I) and such conversions constitute further features of the present invention. According to a further feature of the present invention, compounds can be prepared in which n is one or two, by oxidation of the sulfur atom of the corresponding compounds in which n is zero or one. Oxidation of the sulfur atom is generally carried out using, for example, 3-chloroperbenzoic acid in an inert solvent such as dichloromethane at a temperature from -40 ° C to room temperature.

Certain compounds of formula (I) can be converted to agriculturally acceptable salts by known methods. The following non-limiting examples illustrate the invention. The NMR spectra were produced in CDC13, unless otherwise indicated.

Example 1 A solution of 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2,4-dimethylpentan-3 -ol is added. (1.7 g) in dichloromethane to a stirred mixture of pyridinium chlorochromate (1.81 g) and powdered molecular sieve (4A) in dichloromethane at 20 ° C. After 5 hours ether is added, the mixture is filtered through hyflo and evaporated. The residue is purified by dry column chromatography on silica gel, eluting with dichloromethane / ethyl acetate to provide 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3- oxazin-3-yl) -2,4-dimethylpentan-3-one (compound 1, 0.84 g) as a white solid, mp 98.6-101.6 ° C. The following compounds are prepared by proceeding in a similar manner: 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl] -2-methylheptan- 3-one (compound 2, mp 75.8-76.6 ° C); 1- (3, 5-difluorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl] -2-methylpropan-l- ona; (compound 3), mp 156.8-157.8 ° C; 3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3- methylbutan-2-one (compound 27, mp 118-119 ° C); 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylhexan-3-one (compound 29, mp 118-119 ° C); 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3) -yl) -2,5-dimethylhexan-3-one (compound 30, mp 72-73 ° C); 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl] -2-methylpentan-3-one (compound 28, mp 102-103 ° C); 2- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl) 4H-1, 3-oxazin-3-yl) -2-methylundecan-3 -one (compound 38), NMR 0.8 (t, 3H), 1.2 (m, 10H), 1.4 (s, 6H), 1.6 (c , 2H), 1.85 (s, 3H), 2.4 (t, 2H), 5.15 (s, 2H), 7.25 (m, 5H), 2- (2,3-dihydro-6-methyl-4-oxo-5) - phenyl -4 H -1,3-oxazin-3-yl) -2,4-dimethylhexan-3-one (compound 32, mp 84-84.5 ° C); l-cyclopropyl -2- (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-l-one (compound 31, p.f. 126-128 ° C); 2- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -2,, 4-trimethylpentan-3-one (compound 90, p. 139-140.5 ° C); 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methyl-1- (2-thienyl) propan-1-one (compound 91, mp 152-153.5 ° C); 2- (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -1- (3-furyl) -2-methylpropan-1-one ( compound 92, mp 164-165 ° C); 1- (2-benzothrazole) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-1-one (compound 93, mp 169-169.5 ° C); 1- (3,4-dichlorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methylbutan-2- ona (compound 94, mp 120-121 ° C); 1- (3,5-dichlorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -3-methylbutan-2 -one (compound 39, mp 120.5-121.5 ° C); 3 - (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -1- (3,5-dimethylphenyl) -3-methybutan- 2 -one (compound 95, mp 119-120 ° C); 1- (4-chlorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -3-methylbutan-2-one (compound 96, mp 165.5-166 ° C); 1-cyclopentyl -2 - (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -2-methylpropan-1-one (compound 97, mp 126-128 ° C); 3 - (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -3-methyl) -1- (3-methylphenyl) butan-2- ona (compound 98, mp 97.5-99 ° C); 2- (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methylnonan-3-one (compound 35, mp 59-60 °) C); 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -2-methyloctane-3-one (compound 34, mp 82-82.5 ° C); 3 - (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -3-methyl-1- (phenyl) butan-2-one (compound 99, mp 117-118 ° C); 1- (3, 5-difluorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methylbutan-2- ona (compound 100, m.p. 92.5-94 ° C); 2- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -2-methyl-1- (6-methylpyrid-2-yl) propan-1-one (compound 101, mp 76.5-77.5 ° C); 2- (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2,6-dimethylheptan-3-one (compound 102, mp 83.5- 84 ° C); 2- (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methyl-1- (4-trifluoromethyl-pyrid-2-yl) propan -1-one (compound 103, mp 134-135 ° C); 1- (2, 5-difluorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methylbutan-2- ona (compound 104, mp 98-99 ° C); 1- (2-chlorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methylbutan-2-one ( compound 105, mp 140.5-141 ° C); 1- (2,4-difluorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methylbutan-2- ona (compound 106, mp 135-136 ° C); 1- (4-fluorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methylbutan-2-one (compound 107, mp 118-119 ° C); 2- (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -2-methylhept-6-en-3-one (compound 108, p. 91-92 ° C); 2- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-1,3-oxazin-3-yl) -2,4-dimethylheptan-3-one (compound 109), NMR 0.7 (t, 3H), 1.0 (d, 3H), 1.15-1.3 (m, 4H), 1.45 (s, 6H), 1.85 (s, 3H), 2.9 (m, 1H), 5.2 (s, 2H) ), 7.25 (m, 5H); 2- [2,3-dihydro-5- (2-f luorofenyl) -6-methyl-4-oxo-4H-1, 3-oxazin-3-yl] -2-methylheptan-3-one (compound 43) ), NMR 0.9 (t, 3H), 1.25 (m, 2H); 1.45 (s, 6H), 1.6 (c, 2H), 1.9 (s, 3H), 2.5 (t, 2H), 5.3 (s, 2H), 7.1 (m, 2H), 7.3 (m, 2H); 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methylhept-5-en-3-one (compound 110), NMR 1.15 (d, 3H), 1.2 (s, 6H), 1.85 (s, 3H), 5.0 (c, 1H), 5.2 (s, 2H), 5.7 (c, 1H), 7.25 (m, 5H); 2- [2,3-dihydro-5- (2-fluorophenyl) -6-methyl-4-oxo-4H-1, 3-oxazin-3-yl] -2-methylhexan-3 -one (compound 111), NMR 0.8 (t, 3H), 1.4 (s, 6H), 1.6 (m, 2H), 1.8 (s, 3H), 2.4 (t, 2H), 5.2 (s, 2H), 7.05 (m, 2H), 7.25 (m, 2H); 2- [2,3-dihydro-5- (2-methoxyphenyl) -6-methyl-4-oxo-4H-1, 3-oxazin-3-yl] -2-methylhexan-3 -one (compound 112, mp) 87-88.5 ° C); 2- [2,3-dihydro-5- (2-methoxyphenyl) -6-methyl-4-oxo-4H-1, 3-oxazin-3-yl] -2-methylheptan-3-one (compound 48, mp. 65-67 ° C); 2- [2,3-dihydro-5- (2-methoxyphenyl) -6-methyl-4-oxo-4H-1, 3-oxazin-3-yl] -2-methylhept-6-en-3-one ( compound 113, mp 62-63 ° C); l-cyclohexyl-2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methylpropan-l-one (compound 36, mp 94-96 ° C); 2- [2,3-dihydro-6-methyl-4-oxo-5- (2-thienyl) -4H-1,3-oxazin-3-yl] -2-methylhexan-3-one (compound 114, mp. 94 ° C; 2- [2,3-dihydro-6-methyl-4-oxo-5- (2-thienyl) -4H-1,3-oxazin-3-yl] -2-methylheptan-3-one (compound 56, mp. 75-76 ° C); 2- (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl] -2,5-dimethylheptan-3-one (compound 115, mp 55- 56 ° C); 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl] -2,6,6-trimethylheptan-3-one (compound 116, mp 107.5-109 ° C); 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -4-ethyl- 2-methylhexan-3 -one (compound 117), NMR 0.77 (t, 3H), 1.4 (m, 2H), 1.5 (s, 6H), 1.6-1.7 (m, 2H), 1.8 (s, 3H), 2.65 (m, 1H), 5.2 (s, 2H), 7.1-7.3 (m, 5H); 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl] -2,5,5-trimethylhexan-3-one (compound 118 (, NMR 0.92 (s, 9H), 1.33 (s, 6H), 2.1 (s, 3H), 2.4 (s, 2H), 5.2 (S, 2H), 7.15-7.3 (m, 5H); 2- [2, 3-dihydro-6-methyl-4-oxo-5- (2-thienyl) -4H-1,3-oxazin-3-yl] -2-methylhept-6-en-3-one (compound 119, mp 79) -81 ° C); 1-cyclopentyl-2- [2,3-dihydro-6-methyl-4-oxo-5- (2-thienyl) -4H-1,3-oxazin-3-yl] -2- methylpropan-1-one (compound 120, mp 103-104.5 ° C); l-cyclobutyl-2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl] -2-methylpropan-l-one (compound 33, mp 136-137.5 ° C) and 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl] -2-methyl-7,7, 7-trifluoroheptan-3 -one (compound 121, mp 83-84.5 ° C) The same procedure is used but with the exclusion of the molecular sieve to prepare the following compounds: 1- (2-fluoro-5-trifluoromethylphenyl) -2 - (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl] -2-methylpropan-l-one (compound 4), mp 113-114.6 ° C 1- (3-chlorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl] -methylbutan-2-one ( compound 5), mp 134.5-136 ° C; and 1- (3-trifluoromethylphenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3 -yl] -3-methylbutan-2 -one (compound 6), mp 105.9-106.9 ° C; Example 2 Chromic acid [1.7 ml of a solution prepared by the addition of a solution of sodium dichromate (0.4 g) in water (1.2 ml) to concentrated sulfuric acid (0.54 ml) and diluted to 25 ° C is added dropwise at 25 ° C. 2 ml with water] to a stirred solution of 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -3-methylhex-5- en-3-ol (1.0 g) in ether. After 18 hours the ether layer is separated, washed with a solution of sodium bicarbonate (2N) and with brine, dried (magnesium sulfate) and evaporated. The residue is purified by dry column chromatography, on silica gel eluting with dichloromethane to provide 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3) il) -2-methylhex-5-en-3-one (compound 7, 0.12 g) as a yellow oil, NMR d 1.4 (s, 6H), 1.88 (s, 3H), 3.22 (d, 2H), 5.05 (m, 2H), 5.22 (s, 2H), 5.9 (m, 1H), 7.2-7.35 (m, 5H). The following compounds of formula (I) are prepared by proceeding in a similar manner: 4- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -4-methylpent-l-en-3-one (compound 8), mp 123-124 ° C; 1- (4-fluorophenyl) -2- [5- (2-fluorophenyl) -2,3-dihydro-6 -methyl-4-oxo-4H-l, 3-oxazin-3-yl] -2-methylpropan-l-one (compound 9), mp 92-96 ° C; 4- (2,3-dihydro- 6 - methyl -4 -oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -4-methylpent-1-yn-3-one (compound 10) as a yellow oil, XH-NMR 1.45 (s, 6H), 1.9 (s, 3H), 3.05 (s, 1H), 5.25 (s, 2H), 7.2-7.4 (m, 5H), 2- [5- (2-fluorophenyl) -2, 3-dihydro- 6-methyl-4-oxo-4H-1,3-oxazin-3-yl] -1- (2-methylphenyl) -2-methylpropan-1-one (compound 11) as a colorless gum, 1H-NMR 1.7 ( s, 6H), 1.85 (s, 3H), 2.39 (s, 3H), 5.4 (s, 2H), 6.9-7.7 (m, 8H); 1- (4-fluoro-3-methylphenyl) -2- [ 5- (2-fluorophenyl) -2,3-dihydro-6-methyl-4-oxo-4H-1, 3-oxazin-3-yl] -2-methylpropan-1-one (compound 12) as a yellow oil , RMN ^ H d 1.6 (s, 6H ), 1.85 (s, 3H), 2.2 (s, 3H), 5.4 (s, 2H), 6.85-7.9 (m, 7H); 2- (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -2-methyl-1- (2-methylphenyl) propan-1-one (compound 13) as a colorless oil, 2 H NMR 1.6 (s, 6H), 1.85 (s, 3H), 2.35 (s, 3H), 5.3 (s, 2H), 6.9 (dd, 2H), 7.05 (t, 1H), 7. 1-7.3 (m, 5H), 7.55 (d, 1H); 1- (4-fluorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-l-one ( compound 14) as a yellow solid, XE-NMR 1.55 (s, 6H), 1.85 (s, 3H), 5.35 (s, 2H), 6.9-7.05 (m, 4H), 7.15-7.25 (m, 3H), 8.0 (dd, 2H); and 1- (4-fluoro-3-methylphenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan -1 -one (compound 15) as a cream solid, NMR d 1.55 (s, 6H), 1. 85 (s, 3H), 2.2 (d, 3H), 5.35 (s, 2H), 6.9 (m, 3H), 7.1- 7.3 (m, 3H), 7.75-7.9 (m, 2H).

Example 3 Oxalyl chloride (1.05 g) is added to a stirred mixture of dimethyl sulfoxide (1.3 g) in dichloromethane at -60 ° C. After 10 minutes, add 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -2-methyl-1-phenylpropan- 1-ol (1.86 g), followed after 0.5 hours by triethylamine (2.8 g). The mixture is heated to room temperature, poured into water and the organic phase is washed with water, dried (magnesium sulfate) and evaporated to yield, after purification by column chromatography on silica gel and eluting with hexane / ethyl acetate (5: 1), 2- (2,3-dihydro-6) -methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methyl-1-phenylpropan-1-one (compound 16, mp 122-123 ° C). The following compounds of formula (I) are prepared by proceeding in a similar manner: 1- (2-chlorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -2-methylpropan-l-one (compound 17, mp 142-145 ° C); 1- (3-chlorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-l-one ( compound 18, mp 134-136 ° C); 1- (4-chlorophenyl) -2 - (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-l-one ( compound 19, mp 131-132 ° C); 1- (3-trifluoromethylphenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-f-4H-l, 3-oxazin-3-yl) -2-methylpropan-1- ona (compound 20, mp 108-109 ° C); and 1- (3,5-dichlorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-f-4H-l, 3-oxazin-3-yl) -2-methylpropan- l-one (compound 21, mp 164-167 ° C).

Example 4 Isopropylmagnesium chloride (5 ml of a 2M solution in tetrahydrofuran) is added over 10 minutes to a stirred solution of 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3- oxazin-3-yl) -2-methylpropionaldehyde (2 g) in tetrahydrofuran at 0 ° C under an inert atmosphere. The mixture is allowed to warm to 10 ° C for 1 hour, poured into a saturated solution of ammonium chloride and extracted (ether). The organic phase is dried (magnesium sulfate) and evaporated to give 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -2 , 4-dimethylpentan-3-ol (2.26) as a yellow gum, mp 42-54 ° C, 1 H NMR 0.85 (d, 3 H), 0.95 (d, 3 H), 1.4 (s, 3 H), 1.5 (s, 3 H), 1.65 (m, 1 H), 1.85 (s, 3 H) , 3.25 (dd, 1H), 5.0 (d, 1H), 5.1 (d, 1H), 5.25 (d, 1H), 7.15-7.35 (m, 5H). The following compounds of formula (I) are prepared by proceeding in a similar manner: 2- (2,3-dihydro-6-methyl--oxo-5-phenyl-4H-1,3-oxazin-3-yl) - 2-methylheptan-3-ol as a whitish solid, m.p. 76-84 ° C; 2- (2,3-Dihydro-6-methyl-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methylhex-5-en-3-ol as an oil. RMN 4? d 1.35 (s, 3H), 1.49 (s, 3H), 1.88 (s, 3H), 1.9-2.2 (m, 2H), 3.65 (dt, 1H), 4.55 (d, 1H), 5.0 (m, 2H) ), 5.1 (d, 1H), 5.2 (d, 1H), 5.85 (m, 1H), 7.15-7.35 (m, 5H); 4- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -4-methylpent-1-en-3-ol as a yellow oil; NMR XH d 1.35 (s, 3H), 1.5 (s, 3H), 1.85 (s, 3H), 4.05 (m, 1H), 5.0 (d, 1H), 5.1-5.29 (m, 4H), 5.75 (ddd) , 1H), 7.15-7.3 (m, 5H); 1- (4-fluorophenyl) -2- [5- (2-fluorophenyl) -2,3-dihydro-6-methyl-4-oxo-4H-l, 3-oxazin-3-yl] -2-methylpropan- l-ol as a colorless oil, NMR 1.52 (s, 6H), 1.8 (s, 3H), 4.45 (s broad, 1H), 4.75 (s, 2H), 4.8 (s, 1H), 6.9-7.4 (m, 8H); 4- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -4-methylpent-1-yn-3-ol as a yellow oil, NMR XH d 1.5 (s, 3H), 1.55 (s, 3H), 1.85 (s, 3H), 2.35 (s, 1H), 4.35 (dd, 1H), 5.15 (d, 1H), 5.30 (d, 1H) ), 5.85 (d, 1H), 7.15-7.35 (m, 5H); 2- [5- (2-f luorofenyl) -2, 3-dihydro-6-methyl--oxo-4H-1, 3-oxazin-3-yl] -1- (2-methylphenyl) -2-methylpropan -l-ol as a pale yellow oil, NMR XH d 1.4 (s, 3H), 1.65 (s, 3H), 1.8 (s, 3H), 2.3 (s, 3H), 4.7 (d, 1H), 4.88 ( d, 1H), 5.1 (d, 1H), 7.74 (m, 8H); 1- (4-Fluoro-3-methylphenyl) -2- [5- (2-fluorophenyl) -2,3-dihydro-6-methyl-4-oxo-4H-l, 3-oxazin-3-yl] - 2-methylpropan-l-ol as a colorless oil, NMR 4í d 1.3 (s, 3H), 1.8 (s, 3H), 2.2 (s, 3H), 4.65 (s broad, 1H), 4.75 (s, 1H), 5.15 (S, 2H), 6.8-7.4 (m, 7H); 1- (3,5-difluorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-1- ol as a whitish solid, mp 87.6-89 ° C; 1- (2-fluoro-5-trifluoromethylphenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan- l-ol NMR 4í d 1.4 (s, 3H), 1.75 (s, 3H), 1.9 (s, 3H), 4.55 (d, 1H), 4.9 (d, 1H), 5.1 (d, 1H), 6.98 ( d, 1H), 7.12 (t, 1H), 7.28 (dd, 2H), 7.35-7.48 (m, 3H), 7.5-7.6 (m, 1H), 7.7-7.8 (m, 1H); 1- (3-chlorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -3-methylbutan-2-ol as a whitish solid, mp 116.9-118.1 ° C; 1- (3-trifluoromethylphenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methyl-2-butan ol as a whitish solid, mp 67-68.2 ° C; 2 - (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methyl-1- (2-methylphenyl) propan-1-ol as a whitish solid, NMR 4l d 1.3 (s, 3H), 1.55 (s, 3H), 1.7 (s, 3H), 2.3 (s, 3H), 4.7 (d, 1H), 4.88 (d, 1H), 5.1 (d, 1H), 5.55 (d, 1H), 7.0-7.4 (m, 9H); 1- (4-fluorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-1-ol as a colorless oil, NMR 4í d 1.4 (s, 3H), 1.68 (s, 3H), 1.9 (s, 3H), 4. 5 (d, 1H), 4.75 (d, 1H), 4.8 (d, 1H), 5.9 (d, 1H), 7.0 (t, 2H), 7.2-7.45 (m, 7H); 1- (4-fluoro-3-methylphenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan- l-ol as a colorless oil RMN 4í d 1.35 (s, 3H), 1.7 (s, 3H), 2.2 (s, 3H), 4.45 (d, 1H), 4.68 (d, 1H), 4.75 (d, 1H), 5.78 (d, 1H), 6.88 (t, 1H), 6.95-7.05 (m, 2H), 7.2-7.4 (m, 5H); 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methyl-1-methylpropan-1-ol, m.p. 150-154 ° C; 1- (2-chlorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -2-methylpropan-1-ol, pf 141-143 ° C; 1- (3-chlorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -2-methylpropan-1-ol, pf 97-98 ° C; 1- (4-chlorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -2-methylpropan-1-ol, pf 138- 139 ° C; 1- (3-trifluoromethylphenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -2-methylpropan-1-ol, pf 107-108 ° C; and 1- (3,5-dichlorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-1 -ol, pf 141-144 ° C. In proceeding in a similar manner the following compounds of formula (I) were also prepared in which Q is -CH (OH) -. In the table below "Ph" means phenyl, "Me" means methyl, "Et" means ethyl, "Pr" means propyl and "Bu" means butyl. Where the subscripts are omitted they are considered implicit, for example, CH = CH2 means CH = CH2.

Rl R2 R3 R4 R5 p.f. ° C or NMR Ph Me n-octyl Me Me 64.5-67 Ph Me -CH (Me) CH2Me Me Me b Ph Me Cyclopropyl Me Me 64-64.5 Ph Me t-Bu Me Me 122-123 Ph Me 3.4-C12 Benzyl Me Me 112-113 Ph Me 3.5-C12 benzyl Me Me 100.5-101.5 Ph Me 3.5-Me2 benzyl Me Me 108-109 Ph Me 4-C1 benzyl Me Me 91.5-92.5 Ph Me cyclopentyl Me Me 89.5-90 Ph Me 3-Me benzyl Me Me 108.5-109.5 Ph Me n-hexyl Me Me 77.5-79 Ph Me n-pentyl Me Me 78.5-79.5 Ph Me benzyl Me Me 142-143 Ph Me 3.5-F2 Benzyl Me Me 129-130.5 Ph Me - (CH2) 2CHMe2 Me Me 112-112.5 Ph Me 2,5-F2 benzyl Me Me 113-114 Ph Me 2-Cl benzyl Me Me 94.5-95.5 Ph Me 2,4-F2 benzyl Me Me 105.5-106.5 Ph Me 4-F benzyl Me Me 76-78 Ph Me - (CH2) 2CH = CH2 Me Me 74-75 Ph Me -CH (Me) CH2CH2Me Me Me 88.5-90 2-F Ph Me n-Bu Me Me 84.5-86 Ph Me -CH2CH = CHMe Me Me 2-F Ph Me n-Pr Me Me c 2-Ome-Ph Me n-Pr Me Me d 2-Ome-Ph Me n-Bu Me Me e 2-OMe-Ph Me - (CH2) 2CH) CH2 Me Me f Ph Me ciciohexyl Me Me 58.5-60 2-thienyl Me n-Pr Me Me 88-89 2-thienyl Me "n-Bu Me Me 98.5-99 Ph Me -CH2CH (Me) CH2Me Me Me g Ph Me - (CH2) 2CMe3 Me Me Ph Me -CH (CH2Me) CH2Me Me Me RI R2 R3 R4 R5 pf- (° Q Ph Me -CH2CMe3 Me Me 2 -thienyl Me - (CH2) 2CH = CH2 Me Me 66-69 2-thienyl Me cyclopentyl Me Me 81-83 Ph Me cyclobutyl Me Me 109.5-110 Ph Me - (CH2) 3CF3 Me Me 91-92 1-H NMR (ppm): (a) 1.1 (d, 3H), 1.4 (s, 3H), 1.53 (s, 3H), 1.9 (s, 3H), 3.82 (c, 1H), 5.09 (d, 1H), 5.15 and 5.28 (dd, 2H), 7-2-7.4 (m, 5H) (b) 0.95 (m, 6H), 1.3 (m, 3H), 1.4 (d, 3H), 1.6 (d, 3H), 1.9 (s, 3H), 3.4 (c, 1H), 5.0 (c, 1H), 5.15 (d, 1H), 5.35 (d, 1H), 7.35 (m, 5H) (c) 0.9 (t , 3H), 1.2 (m, 2H), 1.35 (s, 3H), 1.5 (s, 3H), 1.6 (m, 2H), 1.9 (s, 3H), 3.5 (t, 1H), 4.6 (d, 1H), 5.1 (d, 1H), 5.3 (d, 1H), 7.0-7.3 (m, 5H) (d) 1.3 (s, 6H), 1.5 (m, 2H), 1.9 (m, 3H), 3.78 (s, 3H), 4.9-5.2 (m, 2H), 5.24 (s, 2H), 6.95 (m, 2H), 7.25 (m, 2H) (e) 0.8 (m, 3H), 1.12 (t, 3H) ), 1.1-1.5 (m, 2H), 1.8 (m, 3H), 3.4 (c, 2H), 3.7 (s, 3H), 4.85 (broad, 1H), 5.1 (m, 1H), 5.2 (m, 1H), 6.9 (m, 2H) ), 7.2 (m, 2H) (f) 1.4 (s, 6H), 1.88 (s, 3H), 2.35 (m, 2H), 2. 6 (m, 2H), 3.75 (s, 3H), 5.0 (m, 2H), 5.27 (s, 2H), 5.75-5.9 (m, 1H), 6.9 (m, 2H), 7.17 (m, 1H) , 7.25 (m, 1H), 9.4 (s, 1H) (g) 0.9 (t, 1H), 0.9 (d, 3H), 1.0-1.3 (m, 4H), 1.4 (s, 3H), 1.55 (s) , 3H), 1.7 (m, 1H), 1.9 (s, 3H), 3.6 (d, 1H), 5.1 (d, 1H), 5.3 (d, 1H), 7.2-7.4 (m, 5H).

Example 5 A solution of sec-butylmagnesium chloride (1.14 ml of a 2M solution in tetrahydrofuran) is added to a stirred solution of 4- (2, 3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -4-methylpent-l-en-3 -one (0.5 g) in tetrahydrofuran which is maintained below 0 ° C under an inert atmosphere. After 2 hours, ethyl acetate and an ammonium chloride solution are added, and the organic phase is washed (brine) and evaporated to give 2- (2,3-dihydro-6-methyl-4-oxo-5-). phenyl-4H-1, 3-oxazin-3-yl) -2,6-dimethyloctane-3-one (compound 122, 0.48 g), NMR 1.55 (s, 3H), 1.6 (s, 3H), 2.1 (s) , 3H), 2.5 (s, 1H), 5.2 (m, 3H), 5.6 (d, 1H), 5.8 (c, 1H), 7.25 (m, 5H). The following compound is obtained by proceeding in a similar manner: 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylhepta- 6-in-3 -one (compound 123), NMR 0.9 (t, 3H), 1.2 (m, 5H), 1.45 (s, 6H), 1.9 (s, 3H), 2.5 (m, 2H), 5.3 ( s, 2H), 7.3 (m, 5H).

Example 6 2-Thienyllithium (4.25 ml) of a 1M solution in tetrahydrofuran is added to a solution of 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3 - il) -2-methylpropion-aldehyde (1.0 g) in tetrahydrofuran while stirring at room temperature under an inert atmosphere. After 72 hours, hydrochloric acid (2M) and ethyl acetate are added, the organic phase is dried (MgSO 4) and evaporated. The residue is purified by chromatography on silica gel eluting with hexane / ethyl acetate (3: 1) to give, after trituration with hexane, 2- (2,3-dihydro-6-methyl-4-oxo-5- phenyl-4H-l, 3-oxazin-3-yl) -2-methyl-l- (2-thienyl) propan-l-ol (0.36 g), m.p. 149-151 ° C. The following compounds are also obtained by proceeding in a similar manner: 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -1- (3 -furyl) -2-met ilpropan- 1 -ol, pf 132-132.5 ° C; 2- (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methyl-1- (6-methyl-2-pyridyl) -1-ol, NMR 1.6 (s, 6H), 1.9 (s, 3H), 2.5 (s, 3H), 4.75 (d, 1H), 5.0 (d, 1H), 5.65 (d, 1H), 7.05 ( d, 1H), 7.15 (d, 1H), 7.2-7.4 (m, 5H), 7.55 (t, 1H); and 2- (2,3-dihydro-6-methyl-4-oxo-5-f-4H-1, 3-oxazin-3-yl) -2-methyl-1- (4-trif luoromethyl) -2- pyridyl) propan-1-ol, NMR 1.6 (s, 3H), 1.6 (s, 3H), 1.85 (s, 3H), 4.5 (d, 1H), 4. 95 (d, 1H), 5.1 (d, 1H), 6.2 (d, 1H), 7.1 (d, 1H), 7.2-7.4 (m, 5H), 7.7 (s, 1H), 8.7 (d, 1H).

Reference Example 1 A solution of 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -2-methylpropanoate (43 g) in tetrahydrofuran is added, lithium aluminum hydride (220 ml of a 1M solution in ether) with stirring at -40 ° C. After 1 hour, the solution is cooled to -70 ° C, diluted with ether and treated with brine by dropwise addition, initially at -70 ° C and then at -30 ° C. After warming to room temperature, the organic layer is dried (magnesium sulfate), evaporated and the residue is purified by dry column chromatography on silica gel eluting with dichloromethane to provide 2- (2,3-dihydro-6-). methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropionaldehyde as a cream solid (22.5 g), 4 NMR? d 1.35 (s, 6H), 1.95 (S, 3H), 5.25 (s, 2H), 7.22-7.38 (m, 5H), 9.42 (s, 1H).

The following compounds were also prepared by proceeding in a similar manner.- 2- [5- (2-fluorophenyl) -2,3-dihydro-6-methyl-4-oxo-4H-1, 3-oxazin-3-yl ] -2-methylpropionaldehyde as a white solid, X H NMR 1.38 (s, 6H), 1.93 (s, 3H), 4.29 (s, 2H), 7.74 (m, 4H), 9.42 (s, 1H); 2- [2,3-dihydro-6-methyl-4-oxo-5- (2-thienyl) -4H-1, 3-oxazin-3-yl] -2-methylpropionaldehyde, NMR 1.38 (s, 6H), 2.12 (s, 3H), 5.22 (s, 2H), 7.0 (m, 2H), 7.3 (m, 1H), 9.42 (s, 1H); and 2- [2,3-dihydro-5- (2-methoxyphenyl) -6-methyl-4-oxo-4H-l, 3-oxazin-3-yl] -2-methylpropionaldehyde, NMR 1.35 (s, 6H) , 1.85 (s, 3H), 3.8 (s, 3H), 5.25 (s, 2H), 6.9-7.3 (m, 4H), 9.4 (S, 1H).

Reference Example 2 A mixture of 5- (2-fluorophenyl) -2,2-dimethyl-6-methyl-4H-l, 3-dioxin-4-one (2.0 g) and ethyl 2- (N-methyleneamino) -2-methylpropionate (1.45 g) is heated under reflux in xylene for 10 hours. After evaporation to dryness, the residue is purified by dry column chromatography on silica gel eluting with cyclohexane / ethyl acetate to provide [5- (2-fluorophenyl) -2,3-dihydro-6-methyl-4-oxo Ethyl 4H-l, 3-oxazin-3-yl] -2-methylpropanoate as a light yellow solid (1.7 g), NMR 1.24 (t, 3H), 1.42 (s, 6H), 1.57 (s, 3H) , 4.15 (c, 2H), 5.3 (s, 2H), 7.74 (m, 4H). The following compound is prepared by proceeding in a similar manner: ethyl propane (2, 3-dihydro-6-methyl-4-oxo-4H-1, 3-oxazin-3-yl) -2-methyl, NMR 1.2 ( t, 3H), • 1.5 (s, 6H), 1.98 (s, 3H), 2.25 (m, 1H); 4.15 (c, 2H), 5.16 (s, 2H).

Reference Example 3 A solution of ethyl 2- (N-methyleneamino) -2-methylpropionate (10.3 g) in xylene is added over 1 hour to a solution of ethyl 2- (2-methoxyphenyl) acetoacetate. (8.51 g) in xylene while heating under reflux. The rate of addition is controlled so that it is equal to the azeotropic distillation rate (by means of a Dean and Stark separator). Subsequently, additional xylene is added and the distillation continues for 3 hours. The mixture is evaporated in vacuo to give 2- [2, 3-dihydro-5- (2-methoxyphenyl) -6-methyl-4-oxo-4H-l, 3-oxazin-3-yl] -2-methylpropanoate. ethyl (14.1 g), NMR 1.25 (t, 3H), 1.55 (s, 6H), 1.8 (s, 3H), 3.75 (s, 3H), 4.15 (m, 2H), 5.3 (s, 2H), 6.9 -7.3 (m, 4H).

Reference Example 4 A mixture of ethyl 2-methoxyphenylacetate (11.6 g), sodium tert -butoxide (12.7 g) and ethyl acetate (15.8 g) in diisopropyl ether is heated at 70 ° C for 2.5 hours and stirred at room temperature for the night . Ethyl acetate and hydrochloric acid (2M) are added and the organic phase is dried (magnesium sulfate) and evaporated. The residue is distilled in vacuo to provide ethyl 2- (2-methoxyphenyl) acetoacetate as a liquid (8.5 g), NMR 1.15 and 1.13 (t, 3H), 1.8 and 2.2 (s, 3H), 3.75 and 3.85 (s). , 3H), 4.1-4.3 (2c, 2H), 5.15 (s, 1H), 6.9-7.3 (m, 4H), 13.1 (s, 1H).

Reference Example 5 A mixture of ethyl 2- (2, 3-dihydro-5-iodo-6-methyl-4-oxo-4H-l, 3-oxazin-3-yl) -2-methylpropanoate (30.0 g), 2- ( tributylstannyl) thiophene (33.5 ml), bis-triphenylphosphine chloride and palladium (3.08 g) and lithium chloride (20.5 g) in tetrahydrofuran is heated at 50 ° C for 24 hours. Additional 2- (tributylstannyl) thiophene (2.8 ml) is added and the mixture is heated for an additional 18 hours. Palladium bis-triphenylphosphine chloride (0.62 g) is added and heating is continued for 18 hours. The mixture is poured into water, extracted (ether) and the organic phase is washed (brine), dried (magnesium sulfate) and evaporated. Purification by chromatography on silica gel provides [ethyl 2, 3-dihydro-6-methyl-4-oxo-5- (2-thienyl) -4H-1, 3-oxazin-3-yl] -2-methylpropanoate (14.5 g), NMR 1.15 (t, 3H), 1.55 (s, 6H), 2.1 (s, 3H), 4.15 (c, 2H), 5.25 (s, 2H), 6.9-7.4 (m, 3H).

Reference Example 6 N-Iodosuccinimide (238 g) is added to a stirred solution of ethyl 2- (2,3-dihydro-6-methyl-4-oxo-4H-l, 3-oxazin-3-yl) -2-methylpropanoate ( 200 g) in acetic acid. The mixture is stirred at 40-45 ° C for 5 hours and then at room temperature overnight, and evaporated. The residue is diluted with ether, washed with water, a solution of sodium carbonate (2M) and brine, dried (MgSO4) and evaporated. A solution of the residue in ethanol is cooled to -40 ° C to provide 2- (2,3-dihydro-5-iodo-6-methyl-4-oxo-4H-1, 3-oxazin-3-yl) -2 ethyl-methylpropanoate (66.9 g), p.f. 85-87 ° C. According to a further feature of the present invention, suitable compositions for herbicidal use are provided consisting of one or more 1,3-oxazin-4-one derivatives of formula I or an agriculturally acceptable salt thereof, in association with, and preferably homogeneously dispersed in, one or more compatible agriculturally acceptable diluents or carriers and / or surfactants (ie, diluents or carriers and / or surfactants of the type generally accepted in the art which are suitable for use in herbicidal compositions and which are compatible with compounds of formula I). The term "homogenously dispersed" is used to include compositions in which the compounds of formula I are dissolved in other components. The term "herbicidal compositions" is used in a broad sense to include not only compositions which are ready for use as herbicides but also concentrates which must be diluted before use. Preferably, the compositions contain from 0.05 to 90% by weight of one or more compounds of formula I. The herbicidal compositions may contain a diluent or carrier as well as a surfactant (for example humectant, dispersant or emulsifier). The surfactants which may be present in herbicidal compositions of the present invention can be of ionic or non-ionic types, for example sulphurocyanates, quaternary ammonium derivatives, condensate-based products of ethylene oxide with alkylphenols or polyarylphenols, for example nonylphenols or octylphenols, or carboxylic acid esters of anhydrosorbitols which have been rendered soluble by etherification of the free hydroxy groups by condensation with ethylene oxide, alkali metal or alkaline earth metal salts of sulfuric acid esters and sulfonic acids and such as dinonylsodium and dioctylsodium sulfosuccinates, and alkali metal and alkaline earth metal salts of high molecular weight sulfonic acid derivatives such as lignosulfonates sodium and calcium and sodium and calcium alkylbenzenesulfonates. Suitably, the herbicidal compositions according to the present invention can constitute up to 10% by weight, for example from 0.05% to 10% by weight of surfactant but, if desired, the herbicidal compositions according to the present invention can constitute proportions Higher surfactants, for example, up to 15% by weight in emulsifiable liquid suspension concentrates and up to 15% by weight in liquid water-soluble concentrates. Examples of suitable solid diluents or carriers are aluminum silicate, microfine silicon dioxide, talc, gypsum, calcined magnesia, kieselguhr, tricalcium phosphate, powdered cork, absorbent carbon black, and clays such as kaolin and bentonite. The solid compositions (which can take the form of wettable powders, granules or powders) are preferably prepared by grinding the compounds of formula I with solid diluents or by impregnating solid diluents or carriers with solutions of the compounds of formula I in volatile solvents. , evaporation of the solvents and, if necessary, grinding the products in such a way that powders are obtained. Granular formulations can be prepared by absorbing the compounds of formula I (dissolved in suitable solvents which, if desired, can be volatile) on solid diluents or carriers in granular form and, if desired, evaporating the solvents or by compositions of granulation in the form of powder obtained as described above. The solid herbicidal compositions, particularly powders and wettable granules may contain wetting or dispersing agents (for example of the types described above) which can also serve, as solids, as diluents or carriers. The liquid compositions according to the invention can take the form of aqueous, organic or aqueous-organic solutions, suspensions and emulsions which can incorporate a surfactant. Suitable liquid diluents for incorporation into liquid compositions include water, glycols, glycol ethers, tetrahydrofurfuryl alcohol, acetophenone, cyclohexanone, isophorone, N-alkylpyrrolidones, toluene, xylene, mineral, animal and vegetable oils, esterified vegetable oils and light and naffenic aromatic fractions. of oil (and mixtures of these diluents). The surfactants which may be present in the liquid compositions can be ionic or non-ionic (for example of the types described above) and, when they are liquids, they can also serve as diluents or carriers. The powders, dispersible granules and liquid compositions in the form of concentrates can be diluted with water or other suitable diluents, for example mineral or vegetable oils, particularly in the case of liquid concentrates in which the diluent or carrier is an oil, to provide compositions ready for use. When desired, liquid compositions of the compound of formula I can be used in the form of self-emulsifying concentrates containing the dissolved active substances in the emulsifying agents or in solvents containing emulsifying agents compatible with the active substances, the simple addition of such concentrates to water produces ready-to-use compositions. Liquid concentrates can be used in which the diluent or carrier is an oil, without further purification using an electrostatic spraying technique.

The herbicidal compositions according to the present invention may also contain, if desired, conventional adjuvants such as adhesives, protective colloids, thickeners, penetrating agents, dispersing agents, stabilizers, sequestering agents, antitorta agents, coloring agents and corrosion inhibitors. These adjuvants can also serve as carriers or diluents. Unless indicated otherwise, the following percentages are by weight. Preferred herbicidal compositions according to the present invention are aqueous suspension concentrates which comprise from 10 to 70% by weight of one or more compounds of formula I, from 2 to 10% of surfactant, from 0.1 to 5% of thickener and from 15 to 87.9% of water; wettable powders which comprise to 90% of one or more compounds of formula I, from -2 to 10% surfactant and from 8 to 88% of a diluent or solid carrier; water-soluble or water-dispersible powders which comprise from 10 to 90% of one or more compounds of formula I, from 2 to 40% of sodium carbonate and from 0 to 88% of solid diluent; liquid water-soluble concentrates which comprise from 5 to 50%, for example from 10 to 30%, of one or more compounds of formula I, from 0 to 25% of surfactant and from 10 to 90%, for example 45 to 85% water-miscible solvent, for example triethylene glycol, or a mixture of solvent miscible in water and water; liquid concentrates in emulsifiable suspension which comprise from 10 to 70% of one or more compounds of formula I, from 5 to 15% of surfactant, from 0.1 to 5% of thickener and from 10 to 84.9% of an organic solvent, per mineral oil example; water-dispersible granules which comprise from 1 to 90%, for example from 25 to 75% of one or more compounds of formula I, from 1 to 15%, for example from 2 to 10% of surfactant and from 5 to 95 %, for example from 20 to 60% solid diluent, for example granulated clay with the addition of water to form a paste and then dried, and emulsifiable concentrates which comprise from 0.05 to 90% and preferably from 1 to 60% of one or more compounds of formula I, from 0.01 to 10%, and preferably from 1 to 10% surfactant, and from 9.99 to 99.94%, and preferably from 39 to 98.99% organic solvent.

The herbicidal compositions according to the present invention can also comprise compounds of formula I in association with, and preferably homogeneously dispersed in, one or more additional pesticidal active compounds and, if desired, one or more diluents or carriers, surfactants and adjuvants conventional acceptable compatible pesticides, as described above. Examples of pesticidal active compounds which may be included in, or may be used in conjunction with the herbicidal compositions of the present invention include herbicides, for example, to increase the range of controlled weed species, for example, alachlor [2-chloro- 2,6 '-diethyl-N- (methoxy-methyl) -acetanilide], atrazine [2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine], bromoxynil [3, 5-dibromo-4] -hydroxybenzonitrile], clortoluron [N '- (3-chloro-4-methylphenyl) -N, N-dimethylurea], cyanazine [2-chloro-4- (1-cyano-l-methylethylamino) -6-ethylamino-1, 3, 5-triazine], 2, 4-D [2,4-dichloro-enoxyacetic acid], dicamba [3,6-dichloro-2-methoxybenzoic acid], diphenzoquat [1,2-dimethyl-3,5-diphenylpyrazolium salts], flampromethyl [N-2- (N-benzoyl-3-chloro-4-fluoroanilino) methyl propionate], fluometuron [N '- (3-fluoro-methylphenyl) -NN-dimethylurea], isoproturon [N' - (4-isopropylphenyl) ) -N, N-dimethylurea], diclofop. { RS acid) - 2 - [4 - 2,4-diclofophenoxy) phenoxy] - propionic acid} , fenoxaprop and fenaxaprop-P. { 2- [4- (6-chloro-l acid, 3-benzoxazol-2-yloxy) phenoxy] -propyromic} , diflufenican. { N- (2,4-difluorophenyl) -2- [3- (trifluoromethyl) phenoxy] -3-pyridinecarboxamide} , tralcoxidim. { 2- [1- (ethoxyimino) propyl] -3-hydroxy-5-mesitylcyclohex-2-enone} , clodinafop. { 2- [4- (5-Chloro-3-fluoro-2-pyridyloxy) -phenoxy] propionic acid} , sulcotrione [2 - (2-chloro-4-methylsulfonylbenzoyl) cyclohexane-1,3-dione], flurtamone. { 5-methylamino-2-phenyl-4- [3- (trifluoromethyl) phenyl] -3 (2H) -furanone} , aclonifen (2-chloro-6-nitro-3-phenoxyaniline), and sulfonylureas (for example nicosulfuron); insecticides, for example synthetic pyrethroids, for example permethrin and cypermethrin, and fungicides, for example carbamates, for example methyl N- (l-butyl-carbamoyl-benzimidazol-2-yl) carbamate and triazoles, for example, 1- (4 -chloro-phenoxy) -3,3-dimethyl-1- (1,2,4-triazol-1-yl) -butan-2-one. Pesticidal active compounds and other biologically active materials which may be included in, or may be used in conjunction with the herbicidal compositions of the present invention, for example those mentioned above and which are acidic, if desired, may be used. in the form of conventional derivatives, for example, amine salts and esters, of alkali metal.

According to a further feature of the present invention, there is provided an article of manufacture comprising at least one of the 1,3-oxazin-4-one derivatives of formula I, or, if preferred, a herbicidal composition as described above, and preferably a herbicidal concentrate which must be diluted before use, comprising at least one of the 1,3-oxazin-4-one derivatives of formula I within a container for the derivative or derivatives mentioned above of formula I, or the herbicidal composition, and instructions physically associated with the aforementioned container that establishes the manner in which the above-mentioned derivative or derivatives should be used before formula I or the herbicidal composition contained therein, to control the growth of weeds. The containers will normally be of the types conventionally used for the storage of chemical substances which are solid at normal ambient temperatures, and herbicide compositions particularly in the form of concentrates, for example metal cans or drums, which may be internally lacquered, and plastic materials, glass jars and plastic materials and, when the contents of the container is a solid, for example granular herbicidal compositions, boxes, for example made of cardboard, plastics and metals, or bags. Containers will normally be of sufficient capacity to contain quantities of the 1,3-oxazin-4-one derivative or herbicidal compositions sufficient to treat at least one acre of soil to control weed growth therein but not to exceed a size which is convenient for conventional management methods. The instructions will be physically associated with the container, for example, by being printed directly on the container or on a label or a fixed label thereto. The instructions will normally indicate that the contents of the container, after dilution if necessary, should be applied for the control of weed growth at application rates between 0.5 g and 5000 g of active material per hectare in the manner and for the purposes described. in the above. The following examples illustrate the herbicidal compositions according to the present invention. The following trademarks appear in the description: Ethylan, Soprophor, Sopropo, Rhodorsil, Atagel, Synperonic, Solvesso, Arkopon, Tixosil.

Example Cl: A suspension concentrate is made from: Derivative of oxazinone (compound 1) 20% Ethylan BCP (surfactant) 0.5% Soprophor FL 0.5% Sopropon T36 (Dispersant) 0.2% Rhodorsil 426R (antifoaming agent) 0.01% Propylene glycol (antifreeze) 5.0% Atagel 50 (anti-settling agent) 2.0% Water up to 100% Their suspension concentrates similar to compound 1 can be prepared with another oxazinone derivative of formula I. Example C2; An emulsion concentrate is made from the following: Derivative of oxazinone (compound 1) 10% Synperonic NPE 1800 (surfactant) 4.9% Arylan CA (surfactant) 5.0 Cyclohexanone (solvent) 9.8% NMP (solvent) 9.8% Solvesso 150 (mixing agent) 5.0% Water up to 100% Note: NMP means N-methylpyrrolidine. Similar suspension concentrates can be prepared by replacing compound 1 with another oxazinone derivative of formula I.

Example C3 A wettable powder is made from the following: Oxazinone derivative (compound 1) 20.0% Arylan SX flakes (surfactant) 3.0% Arkopon T (surfactant) 5.0% Sodium polycarboxylate (dispersant) 1.0% Tixosil 38 (adjuvant) flow) 3.0% Chinese clay 68.0% Similar wettable powders can be prepared by substituting compound I with other oxazinone derivatives of formula I. According to a feature of the present invention, there is provided a method for controlling the growth of weeds (i.e., unwanted vegetation) at a location, which comprises applying to the site an effective herbicidal amount of at least one derivative of the invention., 3-oxazin-4-one of formula I or an agriculturally acceptable salt thereof. For this purpose, the 1,3-oxazin-4-one derivatives are commonly used in the form of herbicidal compositions (ie, in association with compatible diluents or carriers and / or surfactants, suitable for use in herbicidal compositions), example as described in the following. The compounds of formula I show herbicidal activity against dicotyledons (ie, broadleaf weeds) and monocots (eg grasses) by pre-application and / or post-germination. In particular, the compounds show interest in the control of Echinochloa crus-galli, with selectivity in rice. By the term "pre-germination application" it is meant the application to the soil in which the seeds or seedlings of the weeds are present before the germination of the weeds above the surface of the soil. By the term "post-germination application" it is meant the application to the aerial or exposed portions of the weeds which have germinated above the soil surface. For example, compounds of formula I can be used to control the growth of broadleaf weeds, for example, Abutilon theophrasti, Amaranthus retroflexus - Bidens pilosa - Chenopodium album, Galium aparine - Ipomoea spp. for example, Ipomoea purpurea, Sesbania exaltata, Sinapis arvensis, Solanum nigrum and Xanthium strumarium- and grass weeds, for example Alopecurus myosuroides. Avena fatua. Digitaria sanguinalis. Echinochloa crus-galli. Eleusine indica and Setaria spp. for example, Setaria faberii or Setaria viridis, and shrubs, for example, Cyperus esculentus. The amounts of compounds of formula I applied vary with the nature of the weeds, the compositions used, the time of application, the climatic and pedological conditions and (when used to control the growth of weeds in areas where crops grow) the nature of the the crops. When applied to an area where crops grow, the application regime will be sufficient to control the growth of weeds without causing substantial permanent damage to the crop. In general, when considering these factors, the application regimes between 1 g and 1000 g of active material per hectare provide good results. However, it should be understood that higher or lower application regimes may be used, based on the particular weed control problem that arises. The compounds of formula I can be used to control the selectivity of weed growth, for example, to control the growth of other species mentioned in the above by means of prior or subsequent germination application in a directional or nondirectional manner, for example by spraying Directional or non-directional, in a place of infestation with weeds which is an area used, or that will be used for crop growth, for example cereals, for example wheat, barley, oats, corn and rice, soybeans, wild beans and dwarf beans, peas, alfalfa, cotton, peanuts, flax, onions, carrots, cabbage, oilseed turnip, sunflower, sugar beet, and permanent land pasture or sown before or after planting the crop or before or after the germination of the harvest. For the selective control of weeds in a place of infestation with weeds which is an area used, or to be used for the growth of crops, for example the crops mentioned in the above, the application regimes are particularly suitable. and 500 g, and preferably between 25 g and 250 g of active material per hectare. The compounds of the invention are especially useful for controlling grass weed species. The compounds of formula I can also be used to control the growth of weeds, especially those indicated above, by previous or subsequent application to germination in established orchids, other areas of tree growth, for example mountains, forests and parks, and plantations, for example sugarcane, oil palm and sugar plantations. rubber. For this purpose they can be applied in a directional or nondirectional manner (for example by directional or non-directional spraying) to the weeds or on the ground in which they are expected to appear, before or after the planting of trees or plantations in application rates between 50 g and 5000 g, and preferably between 50 g and 2000 g, more preferably between 100 g and 1000 g of active material per hectare. The compounds of fla I can also be used to control the growth of weeds, especially those indicated above, in places which are not crop growing areas, but nevertheless in which weed control is desirable. Examples of such areas where there is no crop growth include airfields, industrial sites, railroad tracks, side roadsides, irrigation routes or other aqueducts, scrub lands and fallow or uncultivated land, particularly where it is desired to control Weed growth in order to reduce fire risks. When used for such purposes in which a total herbicidal effect is often desired, the active compounds are usually applied at higher dosage regimes than those used in crop growing areas as described above. The precise dosage will depend on the nature of the treated vegetation and the desired effect. For this purpose, the application prior to or subsequent to germination, and preferably the application prior to germination, in a directional or non-directional manner (for example by means of directional or non-directional spraying) at application rates between 50 g and 5000 is particularly suitable. g, and preferably between 50 g and 2000 g, more preferably between 100 g and 1000 g of active material per hectare. When used to control the growth of weeds by application prior to germination, the compounds of fla I can be incorporated into the soil in which the weeds are expected to germinate. It will be appreciated that when the compounds of fla I are used to control the growth of weeds by post-germination application, ie, by application to the aerial or exposed portions of germinated weeds, the compounds of fla I will nlly also come into contact with soil and can also exert a control prior to germination in weeds that germinate later in the soil..

When especially long weed control is required, the application of the compounds of formula I can be repeated if desired.

METHOD OF USE OF THE HERBICIDAL COMPOUNDS: TEST METHOD. (TO) a) General Appropriate amounts of the compounds used to treat the plants are dissolved to provide equivalent solutions at application rates of up to 1000 g of test compound per hectare (g / ha). These solutions are applied from a standard laboratory sprayer for herbicide that supplies the equivalent of 290 liters of fluid per spray per hectare. b) Weed Control: Prior to germination Seeds are planted, in 70 mm boxes, and 75 mm deep plastic containers in non-sterile soil. The quantities of seeds per pot are the following: Weed species approximate number of seeds / pot 1) Broadleaf weeds Abutilon theophrasti 10 Amaranthus retroflexus 20 Galium aparine 10 Ipomoea purpurea 10 Synapse arvensis 15 Xanthium strumarium 2. 2) Grass weeds Alopecurus myosuroides 15 Avena fatua 10 Echinochloa crus-galli 15 Setaria viridis 20 3) Juncias Cyperus esculentus 3 Harvest 1) Broad leaf Cotton 3 Soy 3 2) Pastures Corn 2 Rice 6 Wheat 6.

The compounds of the invention are applied to the soil surface containing the seeds, as described in (a). A single pot for each crop and each weed is assigned to each treatment, with non-sprayed controls and controls sprayed with acetone only. After the treatment, the pots are placed on a capillary mat that is kept in a greenhouse and water is added from the top. A visual determination of damage to the crop is made 20-24 days after spraying. The results are expressed as reduction of the percentage in the growth or damage to the crop or weeds, in comparison with the plants in the control pots. c) Weed control: post-germination Weeds and crops are sown directly in John Innes pot, in 75 mm deep and 70 mm square pots, except for Amaranthus, which is extracted in the seedling stage and transferred to the pots a week before spraying. Then the plants are grown in a greenhouse until they are ready for sprinkling with the compounds used to treat the plants. The number of plants per pot is as follows: 1) Broadleaf weeds Number of plants Stage of Species of weeds per growing pot Abutilon theophrasti 3 1-2 leaves Amaranthus retroflexus 4 1-2 leaves Galium aparine 3 l? T whorl Ipomoea purpurea 3 1-2 leaves Sinapis arvensis 4 2 leaves Xanthium strumarium 1 2-3 leaves 2) Grass weeds Number of plants Stage of Species of weeds per growing pot Alopecurus myosuroides 8-12 1-2 leaves Avena fatua 12-18 1-2 leaves Echinochloa crus galli 4 2-3 leaves Setaria viridis 15-25 1-2 leaves 3) Juncias Number of floors Stage of Weed species per growing pot Cyperus esculentus 3 leaves 1) Broad leaf crops Number of floors Stage of Crops by growth pot Cotton 1 leaf Soya 2 leaflets 2) Grass crops Number of plants Stage of Crops per pot growth Corn 2 2-3 leaves Rice 4 2-3 leaves Wheat 5 2-3 leaves The compounds for treating the plants were applied to the plants as described in part (a). Each treatment is assigned a single pot for each crop and each weed species, with controls without spraying and controls sprayed only with acetone. After the treatment, the pots are placed on a capillary mat in a greenhouse, and water is added from the top once after 24 hours and then by controlled irrigation. A visual determination of crop damage and weed control is made 20-24 days after spraying. The results are expressed as reduction of the percentage in growth damage to the crop or to the weeds, in comparison with the plants in the control pots.

TEST METHOD B a) General As in test method A above, but the solutions are applied from an automated sprinkler that supplies the equivalent of 720 liters of spray fluid per hectare. b) Weed Control: Prior to germination Seeds are sown in 70 mm square plastic pots, with 75 mm depth in non-sterile soil, 3 species per pot. The quantities of seeds per pot are the following: Weed species approximate number of seeds / species 1) Broadleaf weeds Abutilon theophrasti 7-8 Amaranthus retroflexus 20 (pinch) Galium aparine 4-5 Ipomoea purpurea 5 Synapse arvensis 7-8 Matricaria odorless 20 (whit) Stellaria media 20 (whit) 2) Grass weeds Alopecurus myosuroides 15-20 Avena fatua 10 Echinochloa crus-galli 15 Setaria viridis 15 Setaria faberi 15 Apera spica-venti 20 (pinch) Harvest 1) Broadleaf Cotton 3 Soy 2 2) Pastures Corn 2 Rice 5 Wheat 5 The compounds of the invention were applied to the soil surface containing the seeds, as described in (a). The pots containing the represented species were assigned to each treatment, with non-sprayed controls and controls sprayed only with acetone. After the treatment, the pots are placed on a capillary mat that is kept in a greenhouse, and water is added from the top. A visual determination of the damage to the harvest is made 17 days after the spraying. The results are expressed as reduction of the percentage in the growth or damage of the crop or weeds, in comparison with the plants in the control pots.

METHOD OF TEST C Subsequent application to germination in paddy, in greenhouse Paddy field soil is filled in 170 cm2 plastic pots, an adequate amount of water and chemical fertilizers are added to it and kneaded to convert it to a state of a paddy. They are transplanted to each pot (two seedlings per pot), rice husked plants (variety, Koshihikaru), which has grown in advance in the greenhouse to a stage of 2 leaves. Then, in each pot, predetermined amounts of Echinochloa oryzicola seeds are sown. Monochoria vaginalis, Lindernia procumbens and Scirpus juncoides respectively, and water is added to a depth of 3 cm. After growing the plants in a greenhouse until Echinochloa oryzicola reaches a 1.5-leaf stage, solutions in 100% acetone are prepared using compounds described in the examples so as to contain the active ingredients in an amount equivalent to 75, 300 and 1200 g / ha. The solutions are applied by dripping with a pipette. After 21 days from application with the chemicals, the herbicidal effects on each weed and the phytotoxicity on the husked rice plants are visually determined, and the results are expressed as a percentage of growth reduction or damage to the harvest or weeds compared to the plants in the control pots. When applied at 1000 g / hectare or less prior to germination in test method A, compounds 1-6, 9-21, 27-36, 38, 39, 43, 56, 90-111, 114-116 , 118-123 of the invention provide at least 80% reduction in the growth of one or more weed species mentioned above; At toxic application levels for weeds, these compounds are selective in at least one crop species. When applied at 1000 g / hectare or less prior to germination in test method B, compounds 7 and 8 of the invention provide at least 90% reduction in the growth of one or more species of weeds listed above .

When applied at 1000 g / ha or less after germination in test method A, compounds 1, 2, 5, 6, 15, 16 and 18 of the invention provide at least 80% reduction in growth of one or more of the weed species mentioned above; At toxic application levels for weeds, these compounds are selective in at least one crop species. When applied at 1200 g / hectare or less, in test method C, compounds 1-10, 13-21, 27-36, 39, 43, 48, 56, 90, 91, 93-100, 102, 104-109, 111-114 and 116-123 and of the invention, provide at least 80% reduction in the growth of one or more weed species listed above. It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it refers. Having described the invention as above, property is claimed as contained in the following:

Claims (18)

REIVINDIC-ATIONS

1. A 1,3-oxazin-4-one derivative of formula

(I) characterized in that: R1 represents phenyl optionally substituted by one to five groups which may be the same or different, which are selected from halogen, hydroxy, lower alkyl, lower haloalkyl, lower alkoxy, lower haloalkoxy, -S (0) nR7, -COzR7 , -COR7, cyano, nitro, -O (CH2) qC02R7 and phenoxy; a five to seven member heteroaromatic ring having from one to four heteroatoms in the ring which may be the same or different which are selected from nitrogen, oxygen and sulfur, the ring may optionally be substituted by one to four groups which may be the same or different, which are selected from halogen, hydroxy, lower alkyl, lower haloalkyl, lower alkoxy, lower haloalkoxy, -S (0) nR7, -C02R7, -COR7, cyano, nitro, -O (CH2) qC02R7 and phenoxy; or an optionally halogenated straight or branched chain alkyl, alkenyl or alkynyl group containing up to ten carbon atoms; R2 represents: a hydrogen atom; or a straight or branched chain alkyl group containing from one to ten carbon atoms which is optionally substituted by one or more groups R8 which may be the same or different, - a straight or branched chain alkenyl or alkynyl group, optionally halogenated, which has up to ten carbon atoms; or a group that is selected from cyano, -CHO,

-COR7 -COzH, -C02R7, -COSR7, -CONR9R10, -CH = NOH, -CH = NOR7, -CH = NOCOR7, -CH = NNR9R10, -CH2CN, -CH2N02 and oxiranyl; R3 represents - (CH2) r- (phenyl or naphthyl optionally substituted by one to five groups which may be the same or different which are selected from halogen, hydroxy, lower alkyl, lower haloalkyl, lower alkoxy, lower haloalkoxy, -S (0 ) nR6, -C02R6, -COR6, cyano, nitro, -O (CH2) qC02R6, phenoxy and -SF5); a - (CH2) s- (five to seven membered heteroaromatic ring having from one to four ring heteroatoms, which may be the same or different, which are selected from nitrogen, oxygen and sulfur, the ring is optionally fused to a phenyl ring or a second heteroaromatic ring of five to seven members having one to four heteroatoms which may be the same or different which are selected from nitrogen, oxygen and sulfur, to form a bicyclic ring system, the monocyclic ring or any ring in the bicyclic system is optionally substituted by one to four groups which may be the same or different, which are selected from halogen, hydroxy, lower alkyl, lower haloalkyl, lower alkoxy, lower haloalkoxy, -S (0) nR6, -C02Rs , -COR6, cyano, nitro, -O (CH2) qC02R6, and phenoxy); an optionally halogenated straight or branched chain alkyl, alkenyl or alkynyl group containing up to ten carbon atoms; an optionally halogenated straight or branched chain alkyl, alkenyl or alkynyl group of up to ten carbon atoms which is substituted by cycloalkyl containing from three to six carbon atoms; or cycloalkyl containing from three to six carbon atoms or cycloalkenyl containing five to six carbon atoms, ring systems which are optionally substituted by a group R6 or one or more halogen atoms, which may be the same or different; R4 and R5 independently represent lower alkyl; R6 and R7 independently represent lower alkyl or lower haloalkyl; n represents zero, one or two; q represents one or two, - r represents zero, one or two, s represents zero or one, - R8 is halogen, '-OH, -OR7, -OCOR7, -S (0) nR7, -NR9RX or azide; R9 and R10 independently represent hydrogen, lower alkyl or lower haloalkyl; Q represents -C (= 0) -, -CH (OH) - or -COR11) (OR11); wherein R 11 represents lower alkyl; or the two groups -OR11, together with the carbon atom to which they are attached, form a cyclic ketal group of five or six members; or an agriculturally acceptable salt thereof. 2. The 1,3-oxazin-4-one derivative of formula

(I), according to claim 1, characterized in that; R1 represents phenyl optionally substituted by one to five groups which may be the same or different, which are selected from halogen, hydroxy, lower alkyl, lower haloalkyl, lower alkoxy, lower haloalkoxy, -S (0) nR7, -C02R7, -COR7 , cyano, nitro, -O (CH2) qC02R7 and phenoxy; or a five to seven member heteroaromatic ring having one to four heteroatoms in the ring which may be the same or different which are selected from nitrogen, oxygen and sulfur, the ring may be optionally substituted by one to four groups which may be be the same or different, which are selected from halogen, hydroxy, lower alkyl, lower haloalkyl, lower alkoxy, lower haloalkoxy, -S (0) nR7, -C02R7, -COR7, cyano, nitro, -0 (CH2) qC02R7 and phenoxy; or an optionally halogenated straight or branched chain alkyl, alkenyl or alkynyl group containing up to ten carbon atoms; R2 represents: a hydrogen atom; or a straight or branched chain alkyl group containing from one to ten carbon atoms which is optionally substituted by one or more R8 groups which may be the same or different; a straight or branched chain, optionally halogenated alkenyl or alkynyl group, having up to ten carbon atoms; or a group that is selected from cyano, -CHO, -COR7. -C02H, -C02R7, -COSR7, -CONR9R10, -CH = NOH, -CH = NOR7, -CH = NOCOR7, -CH = NNR9R10, -CH2CN, -CH2N02 and oxiranyl; R3 represents - (CH2) r- (phenyl optionally substituted by one to five groups which may be the same or different which are selected from halogen, hydroxy, lower alkyl, lower haloalkyl, lower alkoxy, lower haloalkoxy, -S (0) nR6 , -C02R6, -COR6, cyano, nitro, -0 (CH2) qC02R6, phenoxy; - (CH2) s- (five to seven membered heteroaromatic ring having from one to four ring heteroatoms which may be the same or different, which are selected from nitrogen, oxygen and sulfur, the ring is optionally fused to a phenyl ring or a second aromatic ring of five to seven members having one to four heteroatoms which may be the same or different which are selected from nitrogen , oxygen and sulfur, to form a bicyclic ring system, the monocyclic ring or any ring in the bicyclic system is optionally substituted by one to four groups which may be the same or different, which is selected halogen, hydroxy, lower alkyl, lower haloalkyl, lower alkoxy, lower haloalkoxy, -S (0) nR6, -C02R6, -COR6, cyano, nitro, -O (CH2) qC02R6, and phenoxy), - or a linear or branched, optionally halogenated, alkyl, alkenyl or alkynyl group containing up to ten carbon atoms; or cycloalkyl containing from three to six carbon atoms which is optionally substituted by a group R6 or one or more halogen atoms, which may be the same or different, - R4 and R5 independently represent lower alkyl; R6 and R7 independently represent lower alkyl or lower haloalkyl; n represents zero, one or two; q represents one or two; r represents zero or one, s represents zero or one; R8 is a group selected from halogen, -OH,

-OR7, -OCOR7, -S (0) nR7, -NR9R10; R9 and R10 independently represent hydrogen, lower alkyl or lower haloalkyl; Q represents -C (= 0) -, -CH (OH) - or -C (0R13-) (OR11); wherein R 11 represents lower alkyl; or the two groups

-OR11, together with the carbon atom to which they are attached, form a cyclic ketal group of five or six members; or an agriculturally acceptable salt thereof. 3. The compound according to claim 1 or 2, characterized in that R1 represents phenyl or thienyl optionally substituted by one or more groups which are selected from halogen, lower alkyl and lower haloalkyl. 4. The compound according to claim 3, characterized in that R1 represents phenyl. 5. The compound according to any of claims 1 to 4, characterized in that R2 represents a straight or branched chain alkyl group having from one to six carbon atoms. 6. The compound according to claim 5, characterized in that R2 represents methyl.

7. The compound according to any of claims 1 to 6, characterized in that R4 and R5 each represent methyl.

8. The compound according to any of claims 1 to 7, characterized in that Q represents -C (= 0) -.

9. The compound according to any of claims 1 to 8, characterized in that R3 is cyclopentyl.

10. The compound according to any of claims 1 to 8, characterized in that R3 is n-butyl or butenyl.

11. The compound according to claim 1 or 2, characterized in that: R1 represents: phenyl optionally substituted by halogen; R2, R4 and R5 each represent methyl; Q represents -C (= 0) -; R3 represents: - (CH2) r- (phenyl optionally substituted by one or two groups which are selected from halogen and an optionally halogenated alkyl group containing one or two carbon atoms); or a straight or branched chain alkyl, alkenyl or alkynyl group containing up to four carbon atoms; and r is zero or one.

12. The compound according to claim 1 or 2, characterized in that: R1 represents: phenyl or thienyl optionally substituted by halogen or methyl; R2, R4 and R5 each represent methyl; Q represents -C (= 0) -; R3 represents - (CH2) r- (phenyl optionally substituted by one or two groups which are selected from halogen or an optionally halogenated alkyl group containing one or two carbon atoms), - a straight or branched chain alkyl or alkenyl group which contains up to six carbon atoms; or cycloalkyl containing from three to six carbon atoms; and r is zero or one.

13. The compound according to claim 1, characterized in that it has one or more of the following characteristics: R1 represents phenyl or thienyl optionally substituted by halogen or methoxy; R2, R4 and R5 each represent methyl; Q represents -C (= 0) -; R3 represents - (CH2) r- (phenyl optionally substituted by one or two groups which are selected from halogen or methyl); a thienyl, furyl, benzothiazolyl or pyridyl group, optionally substituted by halogen, or methyl (optionally halogenated); an optionally halogenated straight or branched chain alkyl, alkenyl or alkynyl group containing up to eight carbon atoms; or cycloalkyl containing from three to six carbon atoms; and r is zero or one.

14. The compound according to claim 1, characterized in that it is: 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2, 4 -dimethylpentan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methylheptan-3-one; 1- (3, 5-difluorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-l- ona; 1- (2-Fluoro-5-trifluoromethylphenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan- canvas; 1- (3-chlorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -3 -me i lbut an- 2- ona; 1- (3-trifluoromethylphenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methyl-2-butane; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methylhex-5-en-3-one; 4- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -4-methylpent-en-3-one; 1- (4-fluorophenyl) -2- [5- (2-fluorophenyl) -2,3-dihydro-6-methyl-4-oxo-4H-l, 3-oxazin-3-yl) -2-methylpropan- canvas; 4- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -4-methylpent-l-3-one 2- [5- (2-f luorofenyl) -2, 3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -1- (2-methylphenyl) -2- methylpropan-1-one; 1- (4-fluoro-3-methylphenyl) -2- [5 - (2-fluorourenyl) -2,3-dihydro-6-methyl-4-oxo-4H-1, 3 -oxazin-3-yl) -2-methylpropan-1-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methyl-1- (2-methylphenyl) propan-1-one , - 1- (4-fluorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-1- ona; 1- (4-fluoro-3-methylphenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan- canvas; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methyl-1-phenylpropan-1-one; 1- (2-chlorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-1-one; 1- (3-chlorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-1-one; 1- (2-chlorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-l-one; 1- (3-trifluoromethylphenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methylpropan-1-one; 1- (3,5-dichlorophenyl) -2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-1- ona; 3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methylbutan-2-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -3-methylhexan-2-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2,5-dimethylhexan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methyl-pentan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -2-methylundencan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4 H -1,3-oxazin-3-yl) -2,4-dimethylhexan-3-one; 1- cyclopropyl-2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -2-methylpropan-1-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2,4,4-trimethylpentan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methyl-1- (2-thienyl) propan-1 -one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -1- (3-furyl) -2-methylpropan-1-one; 1- (2-benzothiazole) -2- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -2-methylpropan-l-one , 1- (3,4-dichlorofenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -3- me ti lbut an- 2 -ona; 1- (3,5-dichlorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) - 3 -methylbutyl an- 2- ona; 3 - (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) - (3,5-dimethylphenyl) -3-methylbutan-2-one; 1- (4-dichlorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -3-methylbutan-2-one; 1- cyclopentyl -2 - (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -3-methylpropan-2-one; 3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -3-methyl) -1- (3-methylphenyl) butan-2 -one; 2- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-1,3-oxazin-3-yl) -2-ylnonan-3-one; 2- (2,3-Dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methyloctane-3-one; 3- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-1,3-oxazin-3-yl) -3-methyl-1- (phenyl) -butan-2-one, - 1- (3, 5 -dif luorofenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methylbutan -2-ona; 2- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -2-methyl-1- (6-methylpyrid-2-yl) propan-1-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -2,6-dimethylheptan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-f-enyl-4H-l, 3-oxazin-3-yl) -2-methyl-1- (4-trif luoromethylpyrid-2-yl) propan-l-one; 1- (2,5-difluorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-pheny1-4H-1,3-oxazin-3-yl) -3-methylbutan-2 - ona; 1- (2-chlorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl) -3-methylbutan-2-one; 1- (2,4-difluorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methylbutan-2- ona; 1- (4-fluorophenyl) -3- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methylbutan-2-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl) -2-methylhept-6-en-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4 H -1,3-oxazin-3-yl) -2,4-dimethylheptan-3-one; 2- [2,3-dihydro-5- (2-fluorophenyl) -6-methyl-4-oxo-4H-1,3-oxazin-3-yl] -2-methylheptan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl) -3-methylhept-5-en-3-one; 2- [2,3-dihydro-5- (2-fluorophenyl) -6-methyl-4-oxo-4H-1,3-oxazin-3-yl] -2-methylhexan-3-one; 2- [2,3-dihydro-5- (2-methoxyphenyl) -6-methyl-4-oxo-4 H -1,3-oxazin-3-yl] -2-methylhexan-3-one; 2- [2,3-dihydro-5- (2-methoxyphenyl) -6-methyl-4-oxo-4H-1,3-oxazin-3-yl] -2-methylheptan-3-one; 2- [2,3-dihydro-5- (2-methoxyphenyl) -6-methyl-4-oxo-4 H -1,3-oxazin-3-yl] -2-methylhept-6-en-3-one; l-cyclohexyl-2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl] -2-methylpropan-l-one; 2- [2 , 3-dihydro-6-methyl-4-oxo-5- (2-thienyl) -4H-1,3-oxazin-3-yl] -2-methylhexan-3-one; 2- [2,3-dihydro] -6-methyl-4-oxo-5- (2-thienyl) -4H-1,3-oxazin-3-yl] -2-methylheptan-3-one; 2- (2,3-dihydro-6-) methyl-4-oxo-5- (2-thienyl) -4H-1,3-oxazin-3-yl] -2,5-dimethylheptan-3-one; 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl] -2,6,6-trimethylheptan-3 -one; , 3-dihydro-6-methyl-4-oxo-5-phenyl-4H-l, 3-oxazin-3-yl] -4-ethyl-2-methylhexan-3 -one; 2- (2,3-dihydro) - 6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl] -2,5,5-trime-1-yl-3-one-2- [2,3-dihydro-6-] methyl-4-oxo-5- (2-thienyl) -4H-1,3-oxazin-3-yl] -2-methylhept-6-en-3-one; l-cyclopentyl-2- [2, 3- dihydro-6-methyl-4-oxo-5- (2-thienyl) -4H-1, 3-oxazin-3-yl] -2-methylpropan-l-one, -l-cyclobutyl-2- (2, 3 -dihydro-6-methyl-4-oxo-5-phenyl-4H-1, 3-oxazin-3-yl] -2-methylpropan-l-one; 2- (2,3-dihydro-6-methyl-4) -oxo-5-phenyl-4H-1,3-oxazin-3-yl] -2-methyl-7,7,7-trifluoroheptan-3-one, • 2- (2,3-dihydro-6-methyl- 4-oxo-phenyl-4H-1,3-oxazin-3-yl] -2,6-dimethyloctane-3-one; or 2- (2,3-dihydro-6-methyl-4-oxo-5-phenyl) -4H-1; 3-oxazin-3-yl] -2-methylhept-6-yn-3-one

15. A herbicidal composition, characterized in that it comprises an effective amount of a 1,3-oxazin-4- derivative. ona, conf The composition according to any one of claims 1 to 14, or an agriculturally acceptable salt thereof, in association with a diluent or carrier and / or an agriculturally acceptable surfactant.

16. A method for weed control in a location, characterized in that it comprises applying to the site an effective amount of a 1,3-oxazin-4-one derivative according to any one of claims 1 to 14, or a salt agriculturally acceptable thereof, or a herbicidal composition according to claim 15.

17. The method according to claim 16, characterized in that the site is an area used, or to be used, for the growth of crops, and the 1,3-oxazin-4-one derivative is applied at an application rate from 0.001 to 1.0 kg / ha.

18. A process for the preparation of a 1,3-oxazin-4-one derivative of formula (I), according to claim 1 or 2, characterized in that it comprises: (a) when Q represents -C (= 0 ) -, oxidizing the corresponding compound of formula (I) in which Q represents -CH (OH) -; (b) when Q represents -CH (OH) -, reacting an aldehyde of formula (II) wherein R1, R2, R4 and R5 are as defined according to claim 1 or 2, with an organometallic compound of formula R3-M, wherein R3 is as defined according to claim 1 or 2 and M represents a metal group; (c) when Q represents -C (OR11) (OR11) - reacting the corresponding compound of formula (I) in which Q represents -C (= 0) - with an alcohol of formula R11-OH, wherein R11 is as defined in accordance with claim 1; or (d) when n is one or two, oxidize the sulfur atom of the corresponding compound of formula (I) in which n is zero or one; optionally, followed by the conversion of the compound of formula (I) obtained in this way, into an agriculturally acceptable salt thereof.