Palladium-Catalyzed Highly Stereoselective Dearomative [3

Stereoselective construction of highly functionalized heterocyclic molecules is an ongoing concern for the chemical community. Among the various strategies developed with this goal, catalytic asymmetric dearomatization, an attractive method for constucting cyclic molecules with multiple stereocenters from readily available aromatic compounds, has received extensive attention in recent years. Here, we report a highly stereoselective construction of tetrahydrofurobenzofurans and tetrahydrofurobenzothiophenes via palladium-catalyzed dearomative [3 + 2] cycloaddition of nitrobenzofurans and nitrobenzothiophenes, respectively. Good to excellent yields (63%-92%), diastereoselectivity (13/1 -> >20/1 dr), and enantioselectivity (75%-95% ee) were obtained, leading to products with vicinal stereogenic carbon centers. The reaction features wide substrate scope and diverse transformations of the products.