Acid Hydrazide: A Potential Reagent for the Synthesis of Semicarbazones

Abstract

Complex semicarbazone derivatives were successfully synthesized from substituted semicarbazides in acidic ethanol upon heating in the presence of aldehyde. The reaction is functional group tolerant and chemoselective because no terminal hydrazine moiety is present in the substituted semicarbazides. Thus, functional groups such as esters and acetyls, which are prone to reaction with hydrazine, can also be used in this reaction because the terminal hydrazine moiety of the acid hydrazide was protected by aryl isocyanates in order to prepare substituted semicarbazides. In addition, neither of the aryl groups of semicarbazone are dependent on the starting materials (acid hydrazide) and can be changed upon demand. Thus, this reaction protocol provides a simple and effective alternative for the preparation of a wide variety of semicarbazones that could not be synthesized by utilizing conventional methods.