Reductive Amination of Sterically Hindered Arylaminoketones Using a Modified Leuckart Reaction

The Leuckart reaction offers a fast and convenient method for synthesizing various formamides, amines, and large numbers of biologically active compounds and pharmaceuticals. New 5-(N-piperidino)-1-arylpentan-1-ones (1a-f) and 5-(N-piperidino)-1-aryl-1-aminopentanes (2a-f) were synthesized. The properties of starting aminoketones 1a-f for synthesizing arylaminoketones 2a-f under Leuckart reaction conditions and their thermal stability over a broad temperature interval were studied. The optimal conditions for the key synthetic step, i.e., the Leuckart reaction, were determined experimentally.