Recent Developments in Transition-Metal-Catalyzed Asymmetric Hydrogenation of Enamides

The catalytic asymmetric hydrogenation of prochiral olefins is one of the most widely studied and utilized transformations in asymmetric synthesis. This straightforward, atom economical, inherently direct and sustainable strategy induces chirality in a broad range of substrates and is widely relevant for both industrial applications and academic research. In addition, the asymmetric hydrogenation of enamides has been widely used for the synthesis of chiral amines and their derivatives. In this review, we summarize the recent work in this field, focusing on the development of new catalytic systems and on the extension of these asymmetric reductions to new classes of enamides. 1 Introduction 2 Asymmetric Hydrogenation of Trisubstituted Enamides 2.1 Ruthenium Catalysts 2.2 Rhodium Catalysts 2.3 Iridium Catalysts 2.4 Nickel Catalysts 2.5 Cobalt Catalysts 3 Asymmetric Hydrogenation of Tetrasubstituted Enamides 3.1 Ruthenium Catalysts 3.2 Rhodium Catalysts 3.3 Nickel Catalysts 4 Asymmetric Hydrogenation of Terminal Enamides 4.1 Rhodium Catalysts 4.2 Cobalt Catalysts 5 Rhodium-Catalyzed Asymmetric Hydrogenation of Miscellaneous Enamides 6 Conclusions