Patent GB-1351852-A (GB)
Title: Process for the manufacture of 2,2,-disubstituted cycloalkane- 1,3-diones
IPC: C07C45/29
Filed: 1971-04-19
Abstract: 1351852 2,2-Disubstituted cycloalkane-1,3- diones; intermediates therefor SCHERING AG 19 April 1971 [4 April 1970] 25625/71 Heading C2C The invention comprises a process for the manufacture of 2,2-disubstituted cycloalkane- 1,3-diones of the general formula in which n is 1 or 2, R 1  is a C 1 -C 4  aliphatic hydrocarbon group and R 2  is hydrogen or an organic group by reacting a 2-substituted cycloalkane-1,3-dione of the general formula in a liquid medium and in the absence of a basic catalyst with a vinyl ketone of formula R 2 CH 2 COCH 2  = CH 2  and also certain of the 2,2-disubstituted cycloalkane-1,3-diones per se. Preferred starting vinyl ketones are those in which R 2  represents R 3 -(CH 2 ) m - in which m is 0, 1 or 2 and R 3  is hydrogen, a free or esterified carboxyl group; a free, etherified or esterified alpha-hydroxyalkyl group containing 2-4 carbon atoms; a halogen-alkenyl group containing 2-5 carbon atoms; a ketalized oxoalkyl group containing 2-4 carbon atoms; or a phenyl group optionally substituted by one or more halogen atoms or alkyl, amino, alkylamino, acylamino, hydroxyl, alkoxy or acyloxy groups. The Examples describe the preparation of (a) 2 - methyl - 2 - (3<SP>1</SP> - oxobutyl) - cyclopentane- 1,3-dione; (b) 2-ethyl-2-(3<SP>1</SP>-oxobutyl)-cyclopentane-1,3-dione; (c) 2-methyl-(3<SP>1</SP>-oxobutyl)-cyclohexane-1,3-dione; (d) 2-ethyl-2-(3<SP>1</SP>-oxobutyl)-cyclohexane-1,3-dione; (e) 2-butyl-2-(3<SP>1</SP>- oxobutyl)-cyclohexane-1,3-dione; (f) 5-oxo-7-  (1<SP>1</SP> - methyl - cyclopentane - 2<SP>1</SP>,5<SP>1</SP> - dion - 1<SP>1</SP>- yl) heptoic acid methyl ester; (g) 5-oxo-7-4<SP>1</SP>-ethylcyclopentane-2<SP>1</SP>,5<SP>1</SP>-dion-1<SP>1</SP>-yl)-heptoic acid methyl ester; (h) 2-methyl-2-(3<SP>1</SP>-oxopentyl)-cyclopentane-1,3-dione; (j) 2 methyl-2-[3<SP>1</SP>-oxo-6<SP>1</SP>-(mmethoxyphenyl) - hexyl] - cyclopentane - 1,3- dione; (k) 2-methyl-2-[3<SP>1</SP>-oxo-7<SP>1</SP>,7<SP>1</SP>-(o-phenylenedioxy)-octyl]-cyclopentane-1,3-dione; and (1) 2-methyl-2-(3<SP>1</SP>-oxo-7<SP>1</SP>-chloro-6<SP>1</SP>-octenyl)-cyclopentane-1,3-dione. Compounds (a), (b), (c), (d), (e), (g), (k) and (l) are claimed per se. Intermediates in the preparation of compounds (k) and (l) are made as follows. In the production of (k) 5-keto-hexanoic acid ethyl ester is reacted with pyrocatechol to give 5,5-(o-phenylenedioxy)-hexanoic acid ethyl ester; this ester is reduced with lithium aluminium hydride to replace the carboxylic group by a hydroxyl group; this alcohol is oxidized with Collins reagent to give 5,5-(o-phenylenedioxyhexanol); this aldehyde is treated with a Grignard solution (obtained from magnesium, tetrahydrofuran and vinyl chloride) and the product oxidized to give 7,7-(o-phenylenedioxy)-1-octen- 3-one which is converted to compound (k). In the production of compound (1) malonic acid diethyl ester is reacted with dichlor-2-butene to give 4-chloro-3-pentene-1,1-dicarboxylic acid diethyl ester; this diester is reacted with alcoholic potash to give 5-chloro-4-hexenic acid which is reduced with lithium aluminium hydride to give 5-chloro-4-hexen-1-ol; this alcohol is oxidized with Collins reagent to give the corresponding aldehyde which is treated with the above-mentioned Grignard agent followed by oxidation to give 7-chloro-1,6- octadien-3-one; this is converted to compound (1) by the process of the invention.