Iodonium Ion-Induced Cyclization and Aryl Migration of -Hydroxystilbenes for the Synthesis of 3-Aryl-2,3-dihydrobenzofuran.

A facile and versatile protocol for the efficient synthesis of 3-aryl-2,3-dihydrobenzofuran (ADB) has been reported first. This reaction features the cyclization and aryl migration reaction of -hydroxystilbene in ethanol, which is mediated by an iodonium ion, under ambient conditions. A class of ADB was prepared efficiently in good to excellent yields. Mechanism investigation revealed that acids and alcohols facilitated aryl migration, but alkaline and non-alcohol solvents promoted β elimination. The practicality of this strategy was further substantiated by two scale-up reactions and demonstrated in efficient synthetic elaboration.