Process for racemization of vinyl-substituted cyclopropanecarboxylic acid, useful as pyrethrin-type insecticides and intermediates

摘要

Racemization of an optically-active vinyl-substituted cyclopropane-carboxylic acid (I) involves reaction with a nitric compound or an oxide of nitrogen such as nitric acid, a nitrate or nitrogen dioxide. Racemization of an optically-active vinyl-substituted cyclopropane-carboxylic acid of formula (I) involves reaction with a nitric compound or an oxide of nitrogen such as nitric acid, a nitrate or nitrogen dioxide. R<1>, R<2>, R<3> and R<4> = H, halogen, 1-4C alkyl, aryl, or alkoxycarbonyl (all optionally substituted); R<1>+R<2> may optionally = inter-linked to form alkylene (optionally substituted); and X = hydroxyl, halogen, 1-20C alkoxy or aryloxy (both optionally substituted).