COMMUNICATION pubs.acs.org/JACS Convergent Asymmetric Disproportionation Reactions: Metal/Brønsted Acid Relay Catalysis for Enantioselective Reduction of Quinoxalines

bS Supporting Information ABSTRACT: A convergent asymmetric disproportionation of dihydroquinoxalines for the synthesis of chiral tetrahydroqui-noxalines using a metal/Brønsted acid relay catalysis system has beendeveloped.The use of hydrogen gas as the reductantmakes the convergent disproportionation an ideal atom-economical process. A dramatic reversal of enantioselectivitywas observed in the reduction of quinoxalines because of the different steric demands in the 1,2- and 1,4-hydride transfer pathways. Reductionoxidation (redox) reactions constitute one of themost fundamental reaction types in chemistry. They result in changes in the oxidation numbers of the participating chemical species.1 Addition of hydrogen or electrons or removal of oxygen is reduction, and removal of hydrogenor electrons or additionof oxygen is oxidation. Both oxidation and reduction occur simultaneously and in equivalent amounts during any reaction involving either proces