Diastereo-and Enantioselective Construction of Vicinal All-Carbon Quaternary Stereocenters via Iridium/Europium Bimetallic Catalysis

摘要

The diastereo-and enantioselective construction of vicinal all-carbon quaternary stereocenters is a formidable task. We here report a synergistic bimetallic catalysis via a chiral N,N-dioxide-europium (Eu) complex and a phosphoramidite-iridium (Ir) catalyst for the asymmetric allylation of oxindole derivatives by using challenging trisubstituted allylic esters. The allylated products bearing vicinal all-carbon quaternary stereocenters were obtained with good diastereoselectivities (up to 20:1 dr) and excellent enantioselectivities (up to 99% ee). Control experiments showed that the complementary diastereomers of the products were not accessible by the change of the stereochemistry of the chiral N,N-dioxide ligand.