Electrochemical carboxylation of methyl aryl ketones in the presence of atmospheric pressure of carbon dioxide using platinum cathode and dissolved magnesium anode at constant current density of 10 mA/cm2 gave the corresponding α-hydroxy-α-methyl carboxylic acids in 79-84% isolated yields. The precursor of cicloprofen, α-hydroxy-α-methylfluorene-2-acetic acid (1a) and biprofen, α-hydroxy-α-methybiphenyl-4-acetic acid (2a) were readily obtained in good yield by a similar electrochemical carboxylation of 2-acetylfluorene (1) and 4-acetylbiphenyl (2). Cyclic voltammetric studies showed that the reaction is reversible indicating the preferential generation of stable anion radicals from methyl aryl ketones and that further addition of carbon dioxide does not take place in these electrochemical carboxylations.
carbon dioxide - electrochemical carboxylation - α-hydroxy-α-methylcarboxylic acids - methyl aryl ketones - sacrificial anode - cyclic voltammetry
