Facile Reduction of Pyridines with Nickel-Aluminum Alloy

Article abstract of DOI:10.1021/jo00354a021

Nickel-aluminum alloy in dilute base can be used to reduce a variety of pyridines, quinolines, and isoquinoline to the corresponding piperidines, 1,2,3,4-tetrahydroquinolines, and 1,2,3,4-tetrahydroisoquinoline in good yield.The reaction is simple to perform, and high temperatures, high pressures, or hydrogen atmospheres are not required.The reaction is accelerated by substituents in the 2-position and by electron-withdrawing groups in the 3- and 4-positions while electron-supplying groups in the 3- and 4-positions retard the reaction.The major product isolated from the reduction of 2-phenylpyridine was 2-cyclohexylpiperidine hydrochloride.With isoniazid (1) and iproniazid (4) the pyridine ring is hydrogenated before the hydrazine is cleaved.