Bora-alkenes: Metal Coordination and Reactions with BH-boranes

Abstract

The neutral N-heterocyclic carbene stabilized bora-alkene 1, conveniently prepared by a BH borenium/hydroboration route, forms stable copper, gold or palladium π-complexes. The polar bora-alkene B=C system undergoes regioselective hydroboration reactions with the (C₆ F₅ )₂ BH or C₆ F₅ BH₂ ⋅ SMe₂ boranes. The latter reaction involves a subsequent rearrangement that leads to internal hydride vs. isothiocyanate substituent exchange at the borane pair.

Keywords: N-heterocyclic carbene; bora-alkene; boranes; isothiocyanate; metal coordination.