Electrochemical reaction for direct synthesis of amides from aldehydes

Abstract

Conventional synthesis of amide involves the use of harsh condition, strong oxidizing agents, high value metal catalysts or multiple step synthesis of starting materials. To overcome these problems, in this research, we develop a mild electrochemical oxidative amidation directly from commercially available benzyl alcohols and aldehydes with amines. Optimization studies indicate that this electrochemical oxidative amidation can be proceeded via the use of sodium iodide as both electrolyte and mediator in aqueous solution performing in undivided cell at room temperature without additional additive. Under the optimized condition, we are able to perform electrochemical oxidative amidation of various benzyl alcohols and aromatic aldehydes with amines to prepare corresponding amide products (29 examples) in moderate to good yields. Moreover, our electrochemical oxidative amidation can be scaled to one gram synthesis. In addition, portable power charger can be used as alternative electrical source offering a convenience electrolysis setup. The mechanistic investigations reveal that molecular iodine is true oxidizing agent representing in indirect electrolysis fashion. The key benefits of this process are one-pot operation, open air condition, no requirement of external electrolyte, base and oxidizing agent providing an environmentally friendly process for amide synthesis.