Unusual acid-catalyzed regioselective cyclization of chromone epoxides toward synthesis of 2-substituted benzofuran scaffolds.

We report a concise and efficient strategy for the synthesis of the benzofuran core from chromone epoxides. The method proceeds via regiocontrolled epoxide activation, followed by nucleophilic ring opening, intramolecular cyclization, and subsequent aromatization, resulting in the formation of the benzofuran scaffold. This simple reaction strategy avoids the previously reported multi-step process, and the broad substrate scope with good functional group tolerance highlights its synthetic application. Mechanistic insights support an unusual regioselective pathway toward the synthesis of a 2-substituted benzofuran scaffold.