Nitrile reduction in the presence of Boc-protected amino groups by catalytic hydrogenation over palladium-activated Raney-nickel

Polyamines have attracted considerable interest, especially after the discovery of their ubiquitous presence in living cells and their involvement in many metabolic processes.1 As part of a program to synthesize homologues and derivatives of naturally occurring polyamines, we utilized the reduction of nitriles in the presence of Boc-protected amino groups. Nitriles are a versatile synthon for amines in organic chemistry and can be prepared by a variety of methods.2 Furthermore, there are a number of methods available for the subsequent reduction to amines.2 Catalytic hydrogenation3 has been carried out using Raney-nickel,4,5 Pd(OH)2/C,6 Pd/C,7 or PtO28 as catalyst. Alternatively, complex metal hydrides,9 especially NaBH4 + CoCl2·6H2O,10 NaBH4 + NiCl2·6H2O,11 and LiAlH4 variations,12 have been used successfully to achieve the nitrile-amine transformation. Here we report the use of palladium activated Raney-nickel for the reduction of nitriles to primary amines for cases in which other methods were unsuccessful.