Solvent effects in the β-(phosphatoxy)alkyl radical migration as revealed by deuterium labelling and 1H NMR spectroscopy

Abstract

It has been demonstrated through use of a deuterium labelled probe that the β-(phosphatoxy)alkyl radical migration of 1a, previously shown to be non-dissociative in benzene, occurs through a fragmentation recombination mechanism in the polar, protic solvent tert-butanol. Most likely the reaction occurs through the intermediacy of a contact ion pair which does not allow crossover with an external nucleophile. Parallel experiments for the β-(acyloxy)alkyl migration, however, provided no evidence for a dissociative mechanism in any of the solvents tested.