A mechanistic study on cationic Li prompted Diels–Alder cycloaddition of cycloparaphenylene

Abstract

We introduce Li⁺ involving cycloadditions between acetylene and ring-like cycloparaphenylenes (CPPs) in theory. Orbital analysis suggests an inverse electron-demand mechanism in which the diene CPP acts as an electron acceptor. Partial electron transfer to Li⁺ results in a reduced and localized π* orbital of CPP, giving rise to a site-selective reaction with a much smaller barrier.