Asymmetric Decarboxylative Cycloaddition of Vinylethylene Carbonates with β-Nitroolefins by Cooperative Catalysis of Palladium Complex and Squaramide

An efficient method for the enantio- and diastereoselective construction of multisubstituted tetrahydrofurans via asymmetric decarboxylative cycloaddition of vinylethylene carbonates with β-nitroolefins under a cooperative catalysis of palladium complex and squaramide is developed. By using a palladium complex generated in situ from Pd2(dba)3·CHCl3 and phosphoramidite L1 and chiral squaramide OC4 as cooperative catalysts under mild conditions, the process provided multisubstituted tetrahydrofurans bearing a quaternary stereocenter in good to high yields with acceptably high enantio- and diastereoselectivities