Synthesis of 1,1,1-Tris(boronates) from Vinylarenes by Co-Catalyzed Dehydrogenative Borylations–Hydroboration

The selective preparation of 1,1,1-tris­(boronates) from vinylarenes and bis­(pinacolato)­diboron is described. The reactions occur at ambient temperature with excellent selectivity, high yields, and good functional group tolerance. Mechanistic studies suggest that Co­(I)-catalyzed double dehydrogenative borylations generate a 1,1-diborylalkene intermediate, which undergoes hydroboration with pinacolborane formed in situ to yield 1,1,1-tris­(boronate).