Synthesis and Evaluation of Side-Arm-Alkylated Phosphametallocene Phosphines

Syntheses permitting the introduction of one or two methyl substituents at the sp³-hybridized carbon atom in the backbone of enantiopure 2-phospharuthenocenemethyl phosphines are presented. Preliminary Rh-catalyzed hydrogenations of enamides suggest that the interaction of the Cp* group with the side-arm methyl group lying endo to the phosphametallocene modifies enantioselectivity significantly with respect to the side-arm- unsubstituted analogue.