Catalytic Asymmetric Roskamp Reaction of Silyl Diazoalkane: Synthesis of Enantioenriched α-Silyl Ketone.

A catalytic enantioselective Roskamp reaction of silyl diazoalkane to synthesize a highly optically active α-silyl ketone from aldehydes is described. In the presence of a chiral oxazaborolidinium ion catalyst, the reaction provides α-chiral silyl ketones with good yields (up to 97%) and high enantioselectivities (up to >99% ee). In addition, a one-pot procedure using an asymmetric Roskamp/reduction strategy gives highly optically active syn-β-hydroxysilane in good yields (up to 94%) with high enantioselectivities (up to 99% ee) and syn stereoselectivities (>20:1).