Competition of (3+2) annulation and (3+2) cycloaddition in the reaction of alkenes with donor-acceptor cyclopropanes

Lewis acid-initiated reaction of (het)aryl-substituted donor-acceptor cyclopropanes with styrenes was studied. The initiation of the process by tin( IV ) chloride caused the reaction to proceed in two alternative directions, namely, with the formation of substituted cyclopentanes ((3+2) cycloaddition products) and substituted indanes or their hetero analogs ((3+2) annulation products). The chemoselectivity of the reaction was controlled by several factors, such as the reaction conditions and the nature of reacting compounds and initiator.