Interconversion of Optical Isomers of Chrysanthemic Acid and Related Reactions

Abstract

Chrysanthemic acid (2, 2-dimethyl-3-(2-methyl-l-propenyl) cyclopropanecarboxylic acd) is an acid component of pyrethroidal insecticides. There exist four optical isomers originated from two asymmetric carbon atoms at the C-1 and C-3 positions. Insecticidal activities of the synthetic pyrethroids derived from these optical isomers are shown as follows: 1 R-trans ≥ 1 R-cisy<<1 S-trans S-cis. Optical resolution of racemic mixture of chrysanthemic acid conveniently gives each isomer in optically pure from. Highly efficient epimerization at the position of C-1, C-3 and racemization were achieved as the method for the conversion of ineffective isomers into effective ones. Secondly, the relationship between stereochemical interconversion and regioselective ring opening of chrysanthemic acid derivatives was investigated. Some of the ring opening products were successfully converted into optically active form of tetrahydrolavandulol and tetralin musks. © 1982, The Society of Synthetic Organic Chemistry, Japan. All rights reserved.