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

Abstract

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 Introduction2 Asymmetric Hydrogenation of Trisubstituted Enamides2.1 Ruthenium Catalysts2.2 Rhodium Catalysts2.3 Iridium Catalysts2.4 Nickel Catalysts2.5 Cobalt Catalysts3 Asymmetric Hydrogenation of Tetrasubstituted Enamides3.1 Ruthenium Catalysts3.2 Rhodium Catalysts3.3 Nickel Catalysts4 Asymmetric Hydrogenation of Terminal Enamides4.1 Rhodium Catalysts4.2 Cobalt Catalysts5 Rhodium-Catalyzed Asymmetric Hydrogenation of Miscellaneous Enamides6 Conclusions

Cobalt‐Catalyzed Efficient Convergent Asymmetric Hydrogenation of E/Z‐Enamides

“…Among the many synthetic approaches for chiral amines, asymmetric hydrogenation is favored due to its simple operation and high efficiency, which has gradually attracted great attention in recent years [1] . As the most commonly used hydrogenation substrate for the synthesis of chiral amines, enamide has been studied for more than 50 years and is still a research focus at present [2] . Despite great achievements in high enantioselectivity and reactivity, there remain several problems that have not been effectively solved in this topic.…”

“…[1] As the most commonly used hydrogenation substrate for the synthesis of chiral amines, enamide has been studied for more than 50 years and is still a research focus at present. [2] Despite great achievements in high enantioselectivity and reactivity, there remain several problems that have not been effectively solved in this topic. One of the biggest concerns is the E/Z problem.…”

Recent Advances in the Enantioselective Synthesis of Chiral Amines via Transition Metal-Catalyzed Asymmetric Hydrogenation

“…Focusing on the enantioselective synthesis of chiral amines, important advances have been reported in the last ten years, many of them based on the AH of imines, − enamines, and derivatives − and N -heteroarenes. − These advancements are largely driven by a plethora of new chiral phosphorus ligands, including phosphino-oxazolines and P -stereogenic phosphines. , In addition, other chiral phosphine-free metal catalysts, bearing N -heterocyclic carbenes or C,N- and N,N -based ligands, have also shown outstanding catalytic activity . Thanks to these breakthroughs, a wide range of previously not easily accessible chiral amines have been obtained with excellent enantioselectivities.…”

Directing Group Repositioning Strategy Enabled Site- and Enantioselective Addition of Heteroaromatic C–H Bonds to Acyclic Internal Alkenes

“…In asymmetric hydrogenation, the two-point binding of the π bond and a polar group to the metal center greatly facilitates the enantioselective hydrogenation of diverse alkene substrates . Recently, we have taken advantage of this coordination assistance to achieve a number of enantioselective alkenes’ hydrofunctionalizations, where relatively reactive alkynyl C–H and B–H bonds were cleaved.…”