Crystal and molecular structure of a ketocarboxylatocopper(ii) intermediate in the oxygenation of a copper(i) flavonolate complex

Abstract

Flavonol reacts with metallic copper in the presence of 2,2′-bipyridine to give dihydrogen and a mixture of compounds with the stoichiometric composition [Cu ^I (bpy)(fla)] from which on standing only [Cu ^I (bpy) ₂ ] ₂ [Cu ^I (fla) ₃ ] can be isolated; oxygenation of the solution of the mixture results in the ketocarboxylatocopper(II) complex [Cu ^II (bpy)(fla)(2-HOC ₆ H ₄ COCO ₂ )], which hints at a copper-mediated oxidative cleavage of the pyranone ring in the flavonolate ligand via a 1,2-dioxethane intermediate by ³ O ₂ .