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

Abstract

Development of a new heterobimetallic Ga(O-iPr)(3)/Yb(OTf)(3)/Schiff base 2d complex for catalytic asymmetric alpha-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 alpha-additions of alpha-isocyanoacetamides to aryl, heteroaryl, alkenyl, and alkyl aldehydes in good to excellent enantioselectivity (88-98% ee).

Bifunctional Acid Catalysts for Organic Synthesis

“…Similar hypothesis of this kind of cooperative catalysis mechanism has been proposed by Matsunaga, Shibasaki, and co-workers in their heterobimetallic gallium/ytterbium-Schiff base complex catalyzed asymmetric a-addition of isocyanides to aldehydes [99]. Research along this line will be reviewed in another chapter of this book [100].…”

Chemistry and Biology Of Multicomponent Reactions

“…Recently, a catalytic, highly enantioselective variation of this MCR has been described using a heterobimetallic Ga(O i Pr) 3 /Yb(OTf) 3 /chiral Schiff base complex. 48 …”

Cooperative multimetallic catalysis using metallosalens

“…11b). 78 The authors propose a cooperative reaction mechanism, in which the two starting materials are each coordinated to one of the metal centers through their carbonyl moieties, setting up the two compounds for efficient reaction of the isocyanide with the aldehyde (Fig. 11d).…”