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Synthesis 2002(3): 0399-0402
DOI: 10.1055/s-2002-20042
PAPER
© Georg Thieme Verlag Stuttgart · New York

Facile Synthesis of α-Hydroxy-α-Methyl Carboxylic Acids by Electrochemical Carboxylation of Methyl Aryl Ketones

Janmanchi Damodara, Srinivasulu Reddy Krishna Mohanb, Srinivasulu Reddy Jayarama Reddy*a
a Electrochemical Research Laboratories, Department of Chemistry, Sri Venkateswara University, Tirupati 517502, India
Fax: 91(875)448499; e-Mail: jreddy_s@yahoo.com;
b Department de Chimie Organique, Universite de Geneve, Quai Ernest-Ansermet 30, 1211 Geneve 4, Switzerland
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Publication History

Received 11 October 2001
Publication Date:
28 July 2004 (online)

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Abstract

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.

Key words

carbon dioxide - electrochemical carboxylation - α-hydroxy-α-methylcarboxylic acids - methyl aryl ketones - sacrificial anode - cyclic voltammetry