A Heterobimetallic Ga/Yb-Schiff Base Complex for Catalytic Asymmetric α-Addition of Isocyanides to Aldehydes

Development of a new heterobimetallic Ga(O-iPr)3/Yb(OTf)3/Schiff base 2d complex for catalytic asymmetric α-additions of isocyanides to aldehydes is described. Schiff base 2d derived from o-vanillin was suitable to utilize cationic rare earth metal triflates with good Lewis acidity in bimetallic Schiff base catalysis. The Ga(O-iPr)3/Yb(OTf)3/Schiff base 2d complex promoted asymmetric α-additions of α-isocyanoacetamides to aryl, heteroaryl, alkenyl, and alkyl aldehydes in good to excellent enantioselectivity (88−98% ee).