Catalytic Enantioselective Synthesis of Oxindoles and Benzofuranones That Bear a Quaternary Stereocenter

A common feature in indole- and benzofuran-derived natural products is a quaternary stereocenter in the 3-position of the heterocycle. The catalyst (−)-1 promotes the asymmetric synthesis of such compounds 3 (with up to 99 % ee) through the rearrangement of O-acylated benzofuranones (X=O) and oxindoles (X=NR2) 2.