Palladium-Catalyzed Asymmetric Silaborative C−C Cleavage of meso-Methylenecyclopropanes

An enantioselective silaborative C−C cleavage of meso -methylenecyclopropanes ( meso -MCPs) was achieved by using a palladium catalyst bearing a chiral monodentate phosphine ligand. The ( R )-2-bis(3,5-dimethylphenyl)phosphino-1,1‘-binaphthyl gave the highest enantioselectivity in the reactions with (methyldiphenylsilyl)pinacolborane at 50 °C, affording derivatives of 2-boryl-4-silyl-1-butene in high yields with high enantiomeric excesses. The reactions of bicyclic MCPs that have fused five- to eight-membered rings gave the corresponding products with 89−91% ee, whereas a little lower ee was observed in the reaction of a non-fused MCP (81% ee). Synthetic applications of the products were demonstrated through synthesis of β -silyl ketones by H 2 O 2 oxidation and synthesis of stereodefined homoallylic alcohols via homologation−allylboration sequence, in which the chiral β -substituent of the allylborane has critical impact on the diastereochemical outcome.