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Oxidative Coupling of 3-Substituted Catechols
K. M. Bogle, D. J. Hirst, D. J. Dixon*
The University of Manchester and GlaxoSmithKline, Harlow, UK
22 November 2007 (online)
An oxidative coupling of 3-substituted catechols and carbon-centered pro-nucleophiles to generate arylated quaternary stereogenic centers has been developed. During the reaction the catechol is oxidized to a 3-substituted o-benzoquinone and can then act as a Michael acceptor to form the quinone intermediate 3. After a reduction the desired catechol products are obtained with yields up to 95%. The non-asymmetric version of this reaction is catalyzed by polymer-supported 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine (ps-BEMP). An asymmetric version catalyzed by the cinchona alkaloid derivate 5 has also been developed. The scope of the reaction is shown by 16 different non-asymmetric examples.