Asymmetric Desymmetrization of meso-Methylenecyclopropanes

Significance

A novel Pd-catalyzed asymmetric silaborative C-C cleavage of meso-methylene­cyclopropanes (MCPs) produces 2-boryl-4-silyl-1-butene derivatives in good yields and high enantio­selectivities. The most suitable silaboration reagent is Me₂PhSiB(pinacol) and the ligand is a BINAP derivative. Bicyclic MCPs with fused 5-8-membered rings provide the best yields and ee values. Non-fused MCPs result in lower ee and a cyclic acetal-fused MCP resulted in lower yield. The silaboration products are useful as they can be converted into optically active β-silyl ketones (with no epimerization), or participate in a dia­stereoselective homologation-allylboration sequence.