Electrochemical synthesis of heterocyclic compoudsn—XIX. Anodic synthesis of bichromones by oxidation of enaminones

Abstract

Anodic oxidation of enaminones ( 1– 4), prepared from o-hydroxyacetylarenes and N,N-dimethylformamaide dimethylacetal, were performed in acetonitrile—tetraethylamonium perchlorate electrolyte solution by controlled potential electrolysis. As a result of anodic oxidation corresponding bichromones ( 1a– 4a) were isolated in good yields ranging from 42 to 68%. On the bases of the electroanalytical and preparative results the mechanism of the reaction—including electron transfer, cyclization of radical cation, dimerization and proton and dimethylamine elimination—was discussed.