Effects of Electrolyte, Current Density and Electricity Consumption on the Anodic Oxidation of Cyclic Amides

Anodic oxidation of N-alkylamides in the presence of nucleophiles such as water, alcohol or carboxylic acid, affords the respective alpha- hydroxy, -alkoxy or -carboxy derivatives as final products (Eq. 1). The electrochemical properties of three cyclic amides of the type N-acylazacycloalkanes (I - III) (Scheme 1) have been investigated in acetonitrile by cyclic voltammetry. Each one of them exhibits one irreversible anodic wave (at ~2 V) and one irreversible cathodic wave (at around -1.3 V). Preparative anodic oxidation of I - III in methanol at C anodes under various electrochemical conditions (current density, electricity consumption and supporting electrolytes) led to four major products by all three substrates: alpha-methoxy- and alpha,alpha'-dimethoxy cyclic amides, and two cyclic eneamide derivatives. Their relative ratio was found to be highly dependent on the nature of the electrolyte and current density. References [1] E. Steckhan in Organic Electrochemistry (H. Lund, M.M. Baizer, Eds.), 3rd Ed., Chap. 15, pp. 601-607, Marcel Dekker, New York, 1990. [2] T. Golub and J. Y. Becker, J. Electrochem. Soc., 2013, 160 (7), G1-G5. Figure 1