Reactivity of the geminal phosphinoborane tBu 2 PCH 2 BPh 2 towards alkynes, nitriles, and nitrilium triflates.

The reactivity of the geminal phosphinoborane tBu ₂ PCH ₂ BPh ₂ towards terminal alkynes, nitriles and nitrilium salts is investigated. Terminal alkynes react via C-H bond splitting (deprotonation) resulting in the formation of phosphonium borates. In contrast, both nitriles and nitrilium salts undergo addition reactions resulting in the formation of five-membered heterocycles. All compounds were characterized by multinuclear NMR spectroscopy, and single-crystal X-ray structure determinations. Insight into the reaction mechanisms was gained by DFT calculations.