Stereochemical Evidence for Aryl Participation in the Ring Opening of Oxiranes. Ring-Opening Reactions of 1-Benzyl-1,2-epoxycyclohexane under Acidic Conditions

Article abstract of DOI:10.1021/jo00136a023

The reactions of 1-benzyl-1,2-epoxycyclohexane (1) have been investigated and compared with the ones of the corresponding methyl-substituted oxirane (3) in order to evaluate the possibility that an aryl group not directly linked to the oxirane ring can participate in the ring-opening processes.The acid-catalyzed ring-opening reactions of 1 are not completly anti stereoselective and give mixtures of syn and anti addition products accompanied by rearrangement compounds.The stereoselectivity and the amounts of rearrangement products vary noticeably with the reactionconditions.The results obtained and in particular the presence of substantial amounts of syn products observed in the ring-opening reactions of 1, markedly higher than those from epoxide 3, strongly suggest the incursion of aryl participation and have been rationalized through a mechanism implying the intermediacy of a phenonium-type ion.