Dissymmetrically Substituted Diphosphines with Two Atropisomeric Axes and Their Application in Asymmetric Hydrogenation of Imines

Abstract

AbstractDespite the great potential and widespread applications, the majority of diphosphine ligands used in asymmetric catalysis are C2‐symmetric and their structural modifications are often limited. Herein, we reported the design of original enantiopure dissymmetrical diphosphines, BiaxPhos, bearing two atropisomeric axes. Their original chiral architecture combined with important modularity, renders BiaxPhos ligands appealing candidates for asymmetric catalysis, as illustrated by the Ir‐BiaxPhos catalyzed asymmetric imines hydrogenation, furnishing chiral amines with excellent enantioselectivities under mild conditions. Remarkably, combined experimental mechanistic investigations and DFT calculations delineate yet unexplored mechanistic scenario implying the hydrogenation of the enamine tautomeric form instead of the classic reduction of the imine.