Selective Electrocatalytic Hydrogenation of trans-2-Allyl-6-methyl(allyl, phenyl)-1,2,3,6-tetrahydropyridines on the Nickel and Copper Cathodes

Author： Korotaeva L. M. Rubinskaya T. Ya. Gul'tyai V. P.

Publisher： MAIK Nauka/Interperiodica

ISSN： 1023-1935

Source： Russian Journal of Electrochemistry, Vol.39, Iss.11, 2003-11, pp. : 1203-1210

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Abstract

It is shown that the electrocatalytic hydrogenation (ECH) of trans-2-allyl-6-R-1,2,3,6-tetrahydropyridines (R = Me, All, Ph) on a nickel cathode (Ni_disp/Ni) in 40-% aqueous DMF in the presence of excess AcOH yields products of total hydrogenation of all double bonds—relevant trans-2-propyl-6-R₁-piperidines (R₁ = Me, Pr, Ph). Selective hydrogenation of terminal double bonds of allyl substituents in piperideines under study with the retention of the intracycle double bond may be realized on a copper cathode (Cu_ann), provided the stoichiometric ratio between AcOH and the initial substance is observed exactly. In either case, at points of maximum selectivity of ECH processes, the ratio c_AcOH/c_ini = n + 1, where n is the number of hydrogenated bonds. The difference in the ECH mechanisms on the Cu_ann and Ni_disp/Ni cathodes is discussed. The results of hydrogenation of the trans-2-allyl-6-R-1,2,3,6-tetrahydropyridines at the Cu_ann and Ni_disp/Ni cathodes confirm the general character of regularities discovered earlier during ECH of citral.