Catalytically Asymmetric Synthesis of 1,3-Bis(silyl)propenes via Copper-Catalyzed Double Proto-Silylations of Polar Enynes

A copper-catalyzed double proto-silylations of electron-deficient conjugated enynes to synthesize functional bis(silyl)propenes was developed. Under mild reaction conditions, the silylboronate PhMe₂Si-Bpin reacts with the enynes via cascade proto-silylations and yields the corresponding Z-specific bis(silyl)propene products in up to 98% yield and 95% ee. In addition, the enantioselective synthesis of these compounds was also achieved by using enantiopure pyridine-oxazoline-based ligand.