Isomerisation and fragmentation of bitropyl by hydride abstraction and proton addition

Abstract

Hydride abstraction from bitropyl by triphenylmethyl cation yields benzyltropylium ion, presumably via intermediate formation of 7-cycloheptatrienyltropylium ion and subsequent cyclopropylcarbinyl–allylcarbinyl interconversion. In contrast reaction of bitropyl with perchloric acid in acetic acid gives tropylium ion by a carbonium-ion fragmentation process. Mechanisms for these reactions are discussed.