Initiated, tert-butyl hydroperoxide-loaded, low-temperature autoxidation of alkenes: a chemoselective synthesis of allylic hydroperoxides, allowing analysis of the regioselectivity of hydrogen atom abstraction from some unsymmetrically substituted substrates

Abstract

A method for the preparation of allylic hydroperoxides is introduced: the method involves the rapid, low-temperature, initiated autoxidation of an alkene (in these instances 1-methylcyclohexene and the isomeric 4-methyloct-4-enes) in the presence of tert-butyl hydroperoxide. The success of the method relies upon the selectivity of hydrogen atom abstraction from the substrate by the chain-carrying tert-butylperoxyl radicals, according to the preference for formation of the most stable intermediate allylic radicals, and the reduced rates of chain termination via these same radicals. The method gives a regioselectivity for attack broadly in agreement with predictions from Bolland's rules, and a sufficiently high chemoselectivity for allylic hydroperoxide formation that ready isolation of these products in good yield is achieved.