Generation and Application of Homoallylic α,α-Diboryl Radicals via Diboron-Promoted Ring-Opening of Vinyl Cyclopropanes: cis-Diastereoselective Borylative Cycloaddition.

Carbon-centered radicals stabilized by adjacent boron atoms are underexplored reaction intermediates in organic synthesis. This study reports the development of vinyl cyclopropyl diborons (VCPDBs) as a versatile source of previously unknown homoallylic α,α-diboryl radicals via thiyl radical catalyzed diboron-directed ring opening. These diboryl stabilized radicals underwent smooth [3+2] cycloaddition with a variety of olefins to provide diboryl cyclopentanes in good to excellent diastereoselectivity.