Preparation of cyclopropanecarboxylic acid esters

摘要

A process is disclosed for the preparation of an optically active or racemic cyclopropanecarboxylic acid of the formula (I) <IMAGE> (I) wherein R1 and R2 are the same or different and each is lower alkyl or halogen; R is a member of a group which contains various cyclic structures as set forth in the specification, the DIFFERENCE valency bond represents alpha - and/or beta -configuration; the - valency bond represents beta -configuration, which comprises reacting an optically active or racemic cyclopropanecarboxylic acid of the formula (VII) <IMAGE> (VII) with a dimethyl-methylidene-ammonium salt of the formula (VIII) <IMAGE> (VIII) wherein X is halogen or lower alkoxy and Y- is a halide or lower alkylsulfate ion in an anhydrous, inert organic solvent, and sebsequently reacting a dimethyl-acloxy-methylidene-ammonium salt thus obtained with an optically active, inactive or racemic alcohol of the formula R-OH without isolation, in the presence of an organic base.