Copper‐Catalyzed Asymmetric Synthesis of Silicon‐Stereogenic Benzoxasiloles

A Cu‐catalyzed asymmetric synthesis of silicon‐stereogenic benzoxasiloles has been realized via intramolecular Si‐O coupling of [2‐(hydroxymethyl)phenyl]silanes. Cu(I)/difluorphos is found to be an efficient catalytic system for enantioselective Si‐C bond cleavage and Si‐O bond formation. In addition, kinetic resolution of racemic substituted [2‐(hydroxymethyl)phenyl]silanes using Cu(I)/ PyrOx (pyridine‐oxazoline ligands) as the catalytic system is developed to afford carbon‐ and silicon‐stereogenic benzoxasiloles. Ring‐opening reactions of chiral benzoxasiloles with organolithiums and Grignard reagents yield various enantioenriched functionalized tetraorganosilanes .