Asymmetric Hydrogenation of Tetrahydro‐γ‐Carboline Derivatives with Phosphine‐Free Ruthenium Diamine Catalysts

A highly efficient asymmetric hydrogenation of tetrahydro‐ γ ‐carboline derivatives catalyzed by phosphine‐free ruthenium diamine catalysts has been developed, providing the corresponding cis ‐hexahydro‐ γ ‐carbolines with excellent enantioselectivities and diastereoselectivities (up to 99% ee and >20:1 dr). Furthermore, this catalytic protocol is applicable to the gram‐scale synthesis of cardioprotective drug (‐)‐stobadin.