Cyclization and cupric-ion oxidation of 4-(Cyclohex-1-enyl)butyl radical

Abstract

4-(Cyclohex-1-enyl)butyl radical (45), generated by thermolysis of the appropriate diaoyl peroxide (32), or by treatment of 4-(oyclohex-1-enyl)butyl bromide (34) with tributylstannane, readily undergoes intramolecular homolytic addition. The rate constants for the 1,5- and 1,6-modes of oyclization in benzene at 65º have been determined as 3.8 x 10⁴ s^-l and 3.2 x 10⁴ s^-l respectively. The mechanisms of homolytic addition and of other processes leading to the formation of the observed products are discussed. Cuprio-ion oxidation of 4-(cyclohex-1-enyl)butyl radical (45) affords mainly 4-(cyclohex-1-enyl)but-1-ene (43); the rate constant for the reaction in benzene at 80º is estimated to be c. 4 x 10⁸ 1. mol^-1 s^-1. Evidence for the intermediacy of organo-copper species in this and related oxidation reactions is presented.