Oxidative C-O Cross-Coupling of 1,3-Dicarbonyl Compounds and Their Heteroanalogues with N-Substituted Hydroxamic Acids and N-Hydroxyimides

The oxidative CO cross-coupling of 1,3-dicarbonyl compounds and their heteroanalogues, 2-substituted malononitriles and cyanoacetic esters, with N-substituted hydroxamic acids and N-hydroxyimides was realized. The best results were obtained with the use of manganese(III) acetate [Mn(OAc)(3)] or the cobalt(II) acetate catalyst [Co(OAc)(2cat.)]/potassium permanganate [KMnO4] system as the oxidant. The synthesis can be scaled up to gram quantities of coupling products; yields are 30-94%. The reaction proceeds via a radical mechanism through the formation of nitroxyl radicals from N-substituted hydroxamic acids and N-hydroxyimides.