Ir-Catalyzed Asymmetric Hydrogenation of α-Alkylidene β-Lactams and Cyclobutanones

Chiral β-lactams and cyclobutanones are present in numerous natural and pharmaceutical products. The stereoselective construction of chiral four-membered cyclic compounds is an ongoing challenge for the chemical community. Herein, we report a highly stereocontrolled construction of four-membered ring (mini-sized) β-lactams and cyclobutanones via an Ir/In-BiphPHOX-catalyzed asymmetric hydrogenation, providing the corresponding optically active four-membered ring carbonyl products bearing an α-chiral carbon center with excellent yields (up to 99%) and enantioselectivities (up to 98%) under mild reaction conditions (1.0—2.5 bar H₂ for 1.0—10 h). The reaction presents wide substrate scope. Diverse transformations of the catalyzed products were also conducted to show the potential utility of this protocol.