Synthesis of cyclic amine boranes through triazole-gold(I)-catalyzed alkyne hydroboration.

The first catalytic alkyne hydroboration of propargyl amine boranecarbonitriles is accomplished with triazole-Au(I) complexes. While the typical L-Au species decomposes within minutes upon addition of amine boranecarbonitriles, the triazole-modified gold catalysts (TA-Au) remained active, and allowed the synthesis of 1,2-BN-cyclopentenes in one step with good to excellent yields. With good substrate tolerability and mild reaction conditions (open-flask), this new method provides an alternative route to reach the interesting cyclic amine borane with high efficiency.