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 beta-nitroolefins under a cooperative catalysis of palladium complex and squaramide is developed. By using a palladium complex generated in situ from Pd-2(dba)(3)center dot CHCl3 and phosphoramidite L1 and chiral squaramide OC4 as cooperative catalysts under mild conditions, the process provided multisubstituted tetrahydrofurans bearing a quaternary stereo center in good to high yields with acceptably high enantio- and diastereoselectivities.