Transfer Hydrogenation of Activated CC Bonds Catalyzed by Ruthenium Amido Complexes: Reaction Scope, Limitation, and Enantioselectivity

It was found that the chemoselectivity could be completely switched from CO to CC bonds in the transfer hydrogenation of activated α,β-unsaturated ketones catalyzed by diamine−ruthenium complex. Moreover, this addition via metal hydride had been applied to the reduction of various activated olefins. The electron-withdrawing ability of functional groups substituted on CC bonds at the α- or β-position had strong influence on the reactivity. In addition, a wide variety of chiral diamine−Ru(II)−(arene) systems was investigated to explore the asymmetric transfer hydrogenation of prochiral α,α-dicyanoolefins. Two parameters had been systematically studied, (i) the structure of the N-sulfonylated chiral diamine ligands, in which several chiral diamines substituted on the benzene ring of DPEN were first reported, and (ii) the structure of the metal precursors, and high enantioselectivitiy (up to 89% ee) at the β-carbon was obtained.