Hidden Boron Catalysis: Nucleophile-Promoted Decomposition of HBpin

Simple nucleophiles with structural similarities to known hydroboration catalysts can readily mediate the formation of BH3 and borohydride species from pinacolborane (HBpin). Alkyne and alkene hydroboration reactions were successfully mediated by nucleophiles through BH3 generation, with BH3-catalyzed hydroboration found to dominate catalysis. NMR spectroscopy and kinetic analyses showed that the nucleophiles (NaOBu)-Bu-t, Na[N(SiMe3)(2)], (Bu2Mg)-Bu-n, and (BuLi)-Bu-n only promoted the formation of BH3 and were not true hydroboration catalysts.