Reaction of iridium with cyclopropanes contained in rigid ring systems

Abstract

The reaction of IrCl(CO)(Ph 3P) 2 (Vaska's catalyst) with cyclopropane moieties contained within rigid ring systems was investigated. A variety of substrates were investigated, and several were labeled with deuterium. The results show that exocyclic methylene products predominate in most cases, but a diversity of other products was also obtained. Analysis of products demonstrates a great deal of regioselectivity of reaction. Further, mechanistic pathways leading to products are varied and highly dependent on the electronic and steric environment provided by the substrate. Endocyclopropane compounds seem to be more reactive (when chloroform is used as the reaction solvent) than their exo-counterparts. Catalytic reaction is enhanced in the presence of oxygen and when chloroform is used as the reaction solvent, but regioselectivity of reaction is somewhat decreased. Olefin products and substrates are capable of reaction with Vaska's catalyst and have been shown to establish a dynamic equilibrium in some cases.