Magnesium(II)-Binaphtholate as a Practical Chiral Catalyst for the Enantioselective Direct Mannich-Type Reaction with Malonates

A highly enantioselective direct Mannich-type reaction of aldimines with dialkyl malonates was developed with the use of a Mg(II)-BINOLate salt, which was designed as a cooperative acid-base catalyst that can activate both aldimines and malonates. Optically active beta-aminoesters and alpha-halo-beta-aminoesters could be synthesized In high yields and with high enantioselectivities. This inexpensive and practical Mg(II)-BINOLate salt could be used in gram-scale catalysis.