A Comparison of Phosphaferrocene and Phospharuthenocene Ligands in Rh+‐Catalysed Enamide Hydrogenation Reactions: Superior Performance of the Phospharuthenocene

Enantiopure Cp*-substituted 3,4-dimethyl-5-phenylphosphametallocene-2-methanols (M=Fe, Ru) have been prepared from the corresponding 2-carboxy-(−)-menthylphospholide anion and elaborated into 2-CH2PPh2 phosphametallocenes (13: M=Fe; 14: M=Ru) and 2-CH2PtBuR substituted phospharuthenocenes (R=tBu, Me). The crystal structures of complexes [Rh(1,5-cod)(η2-L)]+BF4− (L=13, 14) reveal significantly different aryl group configurations. Comparative studies of the hydrogenation of para-substituted N-acetylcinnamate esters with these pre-catalysts show a superior performance for the phospharuthenocene derivative in terms of both rate and enantioselectivity.