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.

Automated summary

The synthesis of 2,3-dihydrobenzofuran ring systems remains a topic of significant interest, with a visible-light-driven photoredox-catalyzed radical multicomponent cyclization described in this study. The reaction success relies on the use of both N-alkoxypyridinium salts and sulfur ylides as radical precursors, allowing for the modular synthesis of various 2,3-disubstituted dihydrobenzofurans with good functional group tolerance, easily available starting materials, simple operation, and mild reaction conditions. Mechanistic studies have shed light on some aspects associated with the key radical intermediates.