Patent ID: 6844288

Claim:
A process for the preparation of a compound of formula (II): wherein substituents R1 are hydrogen atoms; the R 2 and R 3 substituents are, independently from each other, C 1 -C 20 -alkyl, C 3 -C 20 -cycloalkyl, C 2 -C 20 -alkenyl, C 6 -C 20 -aryl, C 7 -C 20 -alkylaryl or C 7 -C 20 -arylalkyl radicals.optionally containing silicon or germanium atoms, or where R 2 and R 3 can be joined together to form a 4 to 6 membered ring or a 6 to 20 fused ring system; the R 4 and R 5 substituents, same or different, are hydrogen atoms or —CHR 8 R 9 groups, and R 4 and R 5 can form a ring having 3 to 8 carbon atoms which can contain hetero atoms; the R 6 and R 7 substituents, same or different, are hydrogen, C 1 -C 20 -alkyl, C 3 -C 20 -cycloalkyl, C 2 -C 20 -alkenyl, C 6 -C 20 -aryl, C 7 -C 20 -alkylaryl or C 7 -C 20 -arylalkyl radicals, optionally containing silicon or germanium atoms; and optionally two adjacent R 6 and R 7 substituents can form a ring comprising from 5 to 8 carbon atoms; the R 8 and R 9 substituents, same or different, are hydrogen atoms, C 1 -C 20 -alkyl, C 3 -C 20 -cycloalkyl, C 2 -C 20 -alkenyl, C 6 -C 20 -aryl, C 7 -C 20 -alkylaryl or C 7 -C 20 -arylalkyl radicals, which can form a ring having 3 to 8 carbon atoms which can contain hetero atoms, and/or its double bond isomers comprising the following steps: a) contacting a compound of formula (III): and/or its double bound isomer with a base selected from the group consisting of alkali and earth alkali metal hydroxides or alkoxides in the presence of dimethylsulfoxide or 1-Me-2-pyrrolidinone, thereby forming a corresponding anionic form of formula (III); b) treating the corresponding anionic form of formula (III) with a compound of general formula R 4 R 5 CO, in order to obtain a compound of the formula (IV): c) contacting the compound of formula (IV) with a base, wherein the molar ratio between the base and the compound of formula (IV) is equal to or greater than 2, thereby forming a corresponding di-anionic form of formula (IV); d) treating the corresponding di-anionic form of formula (IV) with a compound of formula (V) CHR 2 R 3 L, wherein L is a halogen atom selected from the group 17 of the Periodic Table of the Elements, and the molar ratio between the compound (V) and the corresponding di-anionic form of formula (IV) is equal to or greater than 2.