Photoredox-Catalyzed Multicomponent Cyclization Of 2-Vinyl Phenols, N-Alkoxypyridinium Salts, And Sulfur Ylides For Synthesis Of Dihydrobenzofurans

The 2,3-dihydrobenzofuran ring systems are a privileged class of oxygen heterocycles, and their synthesis continues to attract considerable effort. Herein, a visible-light-driven photoredox-catalyzed radical multicomponent cyclization of 2-vinyl phenols, N-alkoxypyridinium salts, and sulfur ylides is described. The key to the reaction success involves the use of both N-alkoxypyridinium salts and sulfur ylides as radical precursors. This redox-neutral protocol features good functional group tolerance, easily available starting materials, simple operation, and mild reaction conditions, enabling the modular synthesis of various 2,3-disubstituted dihydrobenzofurans. Mechanistic studies have also elucidated some of the aspects associated with the key radical intermediates.