Process for the preparation of dialkyl (3-chloro-n-propyl)malonates or alkyl (3-chloro-n-propyl)cyanoacetates

摘要

The invention relates to a process for the preparation of dialkyl (3-chloro-n-propyl)malonates or alkyl (3-chloro-n-propyl)cyanoacetates of the general formula I IMAGE in which R1 represents an alkyl radical having 1 to 4 carbon atoms, R2 denotes hydrogen, an alkyl radical having 1 to 4 carbon atoms or denotes a 3-chloro-n-propyl radical and R3 denotes a cyano group or an alkoxycarbonyl radical of the general formula II IMAGE in which latter formula R1' represents an alkyl radical having 1 to 4 carbon atoms, it being possible for R1 and R1' to be identical or different, by reaction of dialkyl malonates or alkyl cyanoacetates of the general formula III IMAGE in which R1, R2 and R3 are as stated above, with 1-bromo-3-chloro-n-propane in solvents in the presence of alkali metal alcoholates at temperatures of not more than 60 DEG C, in which process the solvents used are dipolar aprotic solvents. In this process, the chloro-n-propylation proceeds without side-reactions and produces almost quantitative yields.