Radical-transfer catalysis versus Lewis acid catalysis by the copper(I) chloride/2,2′-bipyridine complex: an illustration of the synthetic significance of captodative radical stabilization

Abstract

The mechanism of the copper(I) chloride/2,2′-bipyridine catalysed π-cyclization of N-(chloromethyl)alk-3-enylcarbamates changes from a cationic process (leading to piperidines) into a radical-transfer process (leading to pyrrolidines) upon introduction of an ester substituent at the reactive carbon atom, owing to the captodative effect.