Asymmetric Conjugate Addition of Grignard Reagents to 3-Silyl Unsaturated Esters for the Facile Preparation of Enantioenriched β-Silylcarbonyl Compounds and Allylic Silanes

A highly enantioselective conjugate addition of Grignard reagents to 3-silyl unsaturated esters to deliver synthetically useful chiral β-silylcarbonyl compounds was developed. The synthetic value of this methodology was further illustrated by the synthesis of enantioenriched β-hydroxyl esters and the facile access granted to various α-chiral allylic silanes. A plethora of diastereoselective transformations of β-silylenolates were also investigated and afforded manifold organosilanes that contained contiguous stereogenic centers with excellent enantioselectivity.