Organocatalytic Asymmetric Synthesis of Si-Stereogenic Siloxanols.

We report the organocatalytic synthesis of Si-stereogenic compounds via desymmetrization of a prochiral silanediol with a chiral imidazole-containing catalyst. This metal-free silylation method affords high yields with enantioselectivity up to 98:2 for various silanediol and silyl chloride substrate combinations (including secondary alkyl, vinyl, and H groups), accessing products with potential for further elaboration. NMR and X-ray studies reveal insight into the H-bonding interactions between the imidazole organocatalyst and the silanediol and the dual activating role of the Lewis basic imidazole to account for the high enantioselectivity.