Electrochemical reduction of oximes in aprotic media

Abstract

The electrochemical reduction in N,N-dimethylformamide of (Z)- and (E)-benzaldoximes, derivatives thereof and some ketoximes has been investigated. The bases electrogenerated during the reduction of the benzaldoximes and their derivatives induce a catalytic elimination reaction producing benzonitrile. Two mechanisms are discussed, one in which the electrogenerated base eliminates water from the incoming substrate and one in which the base abstracts a proton from the intermediate benzaldimine radical with formation of benzonitrile radical anion; this radical anion then reduces the incoming substrate. The electrogenerated base formed during the reduction of the ketoximes deprotonates the oxime to the less reducible oxime anion. During the reduction of an acylated oxime, the parent oxime is formed, probably by cleavage induced by the electrogenerated base, but direct cleavage of the radical anion to the oxime might be possible. © Acta Chemica Scandinavica 1998.