| 摘要 |
PURPOSE:To obtain a racemic modification of chrysanthemum-monocarboxylic acid derivative, rich in the trans isomer, and useful for producing insecticidal esters, by racemizing an optically active chrysanthemum-monocarboxyic acid derivative efficiently with boron bromide. CONSTITUTION:One mol optically active chrysanthemum-monocarboxylic acid derivative of the formula (R is H, 1-20C alkyl, cycloalkyl or aralkyl; * is asymmetric carbon atom) useful as a raw material for pyrethroid based insecticides is racemized with 1/1,000-1/2mol BBr3 in an inert solvent, e.g. n-hexane, at -30-+130 deg.C for 10min-20hr. Thus, the derivative of the formula can be converted into more useful (+) isomer by combination with various optical resolution methods, and the racemic modification of the chrysanthemum-monocarboxylic acid derivative useful for producing insecticidal esters by esterification reaction with various pyrethroid alcohols is obtained. |
