Hydrosilylation of ketones catalyzed by C 2 - symmetric proline-derived complexes 1

Extracoordinate chiral hydrosilanes were generated in situ from triethoxysilane and a C2-symmetric ligand derived from bisproline 7. In the presence of a catalytic amount of ligand 7, prochiral ketones were reduced in moder- ate yield with moderate enantioselectivity (up to 64% ee). Alternatively, TiF4 complexes of 7 were used to provide higher enantioselectivity and with improved yields. The copper complex of ligand 7 and 29 Si NMR data provide some guidance as to the key factors responsible for the observed reactivity at the silicon and at the ligand centre.