Electrochemical (3 + 2) cyclization between amides and olefins

Abstract

Amides and olefins are cheap and readily available industrial materials. Hence, the synthesis of oxazolines from amides and olefins is significant. Regio- and site-selective amino-oxygenation of olefins is one of the most desirable transformations for important oxazoline derivatives, which are common motifs in pharmaceuticals, natural products, agrochemicals, and chiral ligands. However, strong oxidants and iodine reagents create challenges for its applications in organic synthesis. Here, we demonstrate an electrochemical (3 + 2) cyclization between amides and olefins. Various oxazolines are delivered in good yields and with excellent site selectivity and diastereoselectivity simultaneously. Mechanistic studies indicate that chlorine anions, generated from inexpensive 1,2-dichloroethane by cathodic reduction, can be oxidized on the anode and react with alkenes to generate chloronium species, which are key intermediates for this electrochemical cyclization.