Enamines. 9. Polarographic reduction of enamino ketones in aqueous media

The mechanism of the polarographic reduction of cyclic enamino ketones of the pyrrolidine, piperidine, and hexahydroazepine series of two types, viz., compounds in which the α-carbon atom of the enamine is included in the azoheteroring, and enamino ketones in which the double bond is located outside the cyclic system, was investigated. The acyclic analogs were also studied. It is shown that the two- or four-electron reduction depends substantially on the structures of the investigated compounds and the pH of the medium; this in turn is associated with a change in the character, rate, and site of protonation of the enamino ketones and the compounds formed as a result of their reduction.