| 摘要 |
The present invention relates to a three-step method for the preparation of alkyl esters of 4,4-difluoroacetoacetic acid in which in the first step alkyl esters of 4-chloro-4,4-difluoroacetic acid are reacted with trialkylphosphites of formula (III) <?in-line-formulae description="In-line Formulae" end="lead"?>P(OR<SUP>1</SUP>)<SUB>3 </SUB> (III) <?in-line-formulae description="In-line Formulae" end="tail"?> in which R<SUP>1 </SUP>stands for C<SUB>1</SUB>-C<SUB>4</SUB>-alkyl, whereby the residues R<SUP>1 </SUP>can in each case be the same or different, to form alkyl phosphonates of formula (IV) which in the next step are reacted with an amine of formula (V), in which R<SUP>2 </SUP>and R<SUP>3 </SUP>independent of each other stand for hydrogen or C<SUB>1</SUB>-C<SUB>4</SUB>-alkyl or together form -CH<SUB>2</SUB>-CH<SUB>2</SUB>-O-CH<SUB>2</SUB>-CH<SUB>2</SUB>-, to form enamines of formula (VI), in which R<SUP>2 </SUP>and R<SUP>3 </SUP>have the meanings described above, which in the third step are hydrolyzed in the presence of an acid.
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