Pd/NBE-Mediated Annulation of Aryl Triflates with Oxiranes: Efficient Synthesis of 2,3-Dihydrobenzofurans

The direct cyclization of aryl triflates with terminal oxiranes was achieved through palladium/norbornene (Pd/NBE) cooperative catalysis. A wide range of 2,3-dihydrobenzofurans were produced in good to high yields by the strategy. Good functional group tolerance was also demonstrated. This reaction provides an alternative method for preparing value-added 2,3-dihydrobenzofurans starting from readily available phenoxides and expands the scope of Catellani-type reactions in organic synthesis.