Asymmetric Hydrosilylation of Ketones Catalyzed by Diaminocyclohexane/Zinc Complexes: A Comparative Study and Mechanistic Insight

The catalytic enantioselective hydrosilylation activity of zinc is investigated in the presence of two ligands derived from cyclohexane‐1,2‐diamine: N,N′‐dibenzylcyclohexane‐1,2‐diamine (1) and a cage‐like structure composed of six cyclohexane‐1,2‐diamine units (2). The reaction proceeds rapidly, achieving complete conversion within minutes and affording alcohol products with enantiomeric excesses of up to 94%. Despite the favorable results with the cage‐like ligand (2), no significant advantage over ligand (1) is observed. In a second part, to gain insight into the reaction mechanism, various mechanistic experiments are conducted alongside density functional theory calculations. The findings suggest that ligand‐selective silylation leads to the formation of a zinc hydride species, which is likely the active catalytic intermediate in this system.