Metal- and Oxidant-Free Electrosynthesis of Heterocycles from 1,2-Diarylalkene Derivatives

Abstract

Synthesis of heterocycles from 1,2-diarylalkene derivatives through electrosynthesis under metal- and oxidant-free conditions has been discovered. Cathodic reduction of 2-alkenylbenzoic acid or anodic oxidation of 2-alkenylbenzamide, 2-alkenylphenol and 2-alkenylaniline leads to the formation of reactive radical intermediates which afford corresponding phthalide, isochroman-1-one, isoindolin-1-one, benzofuran, and indole in satisfying yields with good functional group tolerance. Interestingly, different chemoselectivities were found in different reaction solvents. Several mechanistic investigations including cyclic voltammetry studies and control experiments were carried out to elucidate the reaction mechanisms.