Electroreductive Intramolecular Heck-Type Cyclization for the Synthesis of Benzofused Oxygenated Heterocycles

Abstract

Conventional synthetic routes to benzofused oxygenated heterocycles, such as dihydrobenzofuran, chromane, and isochromane derivatives, often involve complex synthetic conditions, high costs, and environmental concerns. The key to addressing this challenge lies in achieving transition-metal-free C(sp²)I bond cleavage to enable intramolecular radical cyclization. Inspired by electroreductive strategies, a convenient, transition-metal-free electroreductive tandem reaction is developed for synthesizing dihydrobenzofuran, chromane, and isochromane derivatives. Comprehensive evaluation demonstrates that this approach not only simplifies synthetic conditions but also suppresses competing hydrogenation and halogenation pathways at the exocyclic carbon radical center.