DIELS-ALDER TRAPPING OF ORTHO-QUINONE METHIDES - A NEW ENTRY TO SUBSTITUTED XANTHENE-1,4-DIONES

Highly regioselective Diels-Alder reactions of a non-protected beta-hy droxy quinone have been achieved after formation of chelated lithium a lkoxides. In this report, we demonstrate on a model system, that the s electivity of reactions based on 1,3-dioxy-substituted quinones can be efficiently controlled by the addition of Lewis acid (AlMe3), which c helates the substrate by the two oxygens.