Patent ID: 7585998

Claim:
A method of preparing alkyl esters of 4,4-difluoroacetoacetic acid of formula (I) in which R represents alkyl, comprising (a) in a first step, reacting an alkyl ester 4-chloro-4,4-difluoroacetoacetic acid of formula (II) in which R represents alkyl, with a trialkylphosphite of formula (III) P(OR 1 ) 3 (III) in which each R 1 independently of the others represents C 1 -C 4 -alkyl, to give a alkylphosphonate of formula (IV) in which R and R 1 have the meanings described above, (b) in a second step, reacting the alkylphosphonate of formula (IV) with an amine of formula (V) in which R 2 and R 3 independently of each other represent hydrogen or C 1 -C 8 -alkyl, or R 2 and R 3 together represent —CH 2 —CH 2 —O—CH 2 —CH 2 —, —CH 2 —CH 2 —S—CH 2 —CH 2 —, or —CH 2 —CH 2 —N(R 4 )—CH 2 —CH 2 —, and R 4 stands for hydrogen or C 1 -C 8 -alkyl, optionally in the presence of a diluent, to give an enamine of formula (VI) in which R, R 2 , and R 3 have the meanings described above, and (c) in a third step, condensing the enamine of formula (VI) in the presence of an acid.