Preparation, absolute configuration, and thermolysis of (3R:5R)-(+)-trans-3,5-dimethyl-1-pyrazoline

Abstract

Thermolysis of (3R:5R)-(+)-trans-3,5-dimethyl-1-pyrazoline produces 25.6% of trans-1,2-dimethyl-cyclopropane of 23% optical purity having the S:S configuration. Thermolysis mechanisms which explain the racemization and the double inversion process are discussed. The absolute configuration of active-2,4-pentanediol and 2,4-dibromopentane is correlated with that of 4-hydroxy-1-pentene.