Electrosynthesis of α-keto acetals by a selenium-catalyzed transformation of aryl methyl ketones

Abstract

An indirect electrochemical pathway exists for the conversion of aryl methyl ketones to their corresponding α-keto acetals. Cyclic voltammetry demonstrates that diphenyl diselenide can act as an electron mediator in the conversion because it has the lowest oxidation potential in the reaction mixture. Diphenyl diselenide, upon oxidation at the anode, forms an electrophilic phenylselenenylating reagent which can then react with the aryl methyl ketone in the presence of methanol to form the desired α-keto acetal. Moreover, the diphenyl diselenide can be used in catalytic amounts because it can be recycled by oxidizing the phenylselenenyl anion which results from the formation of the α-keto acetal. Current efficiencies up to 64% were obtained without optmization. Low yields can be attributed to the diffusion of reactant, catalyst, and product through the diaphragm of the divided cell.