Cobalt-Catalyzed and Lewis Acid-Assisted Nitrile Hydrogenation to Primary Amines: A Combined Effort

The selective hydrogenation of nitriles to primary amines using a bench-stable cobalt precatalyst under 4 atm of H₂ is reported herein. The catalyst precursor was reduced in situ using NaHBEt₃, and the resulting Lewis acid formed, BEt₃, was found to be integral to the observed catalysis. Mechanistic insights gleaned from para-hydrogen induced polarization (PHIP) transfer NMR studies revealed that the pairwise hydrogenation of nitriles proceeded through a Co­(I/III) redox process.