Synthesis of fused B,N-heterocycles by alkyne cleavage, NHC ring-expansion and C-H activation at a diboryne

The addition of alkynes to a saturated N-heterocyclic carbene (NHC)-supported diboryne results in spontaneous cycloaddition, with complete BB and CC triple bond cleavage, NHC ring-expansion and activation of a variety of C–H bonds, leading to the formation of complex mixtures of fused B,N-heterocycles.