Cis-(1R,2S)-3,3-dimethyl-2-((4S)-3-methyl-2-(2-propynyl)cyclopent-2-en-1-on-4-yloxyhydroxymethyl)-cyclopropanecarboxylic lactone and method of producing (S)-4-hydroxy-3-methyl-2-(2-propynyl)-cyclopent-2-en-1-on

摘要

The present invention relates to a process for preparing (S)-4-hydroxy-3-methyl-2-(2-propynyl)-cyclopent-2-en-1-one, an important intermediate for the synthesis of insecticides, which comprises condensing cis-(1R,2S)-3,3-dimethyl-2-(dihydroxymethyl)-cyclopropanecarboxylic-lactone, wherein R₂ is a hydrogen atom or a C₁-C₄ alkyl group, with (RS)-4-hydroxy-3-methyl-2-(2-propynyl)-cy- clopent-2-en-1-one in the presence of an acidic catalyst while removing a compound of the formula, R₂OH wherein R₂ is as defined above, the byproduct from the reaction system, to form cis-(1R, 2S)-3,3-dimethyl-2-[(4S)-3-methyl-2-(2-propynyl)-cyclopent-2-en-1-on-4-yloxyhydroxymeth- yl]-cyclopropanecarboxylic lactone as a crystalline form separated from the mixture, and solvolyzing the cis-(1R, 2S)-3,3-dimethyl-2-[(4S)-3-methyl-2-(2-propynyl)-ciclo- pent-2-en-1-on-4-yloxyhydroxymethyl]-cyclopropane-carboxylic lactone with a compound of the formula, R₁OH wherein R, is a hydrogen atom or a C₁-C₄ alkyl group, in an alkaline condition or in the presence of an acidic catalyst.