CRYSTAL AND MOLECULAR-STRUCTURE OF A KETOCARBOXYLATOCOPPER(II) INTERMEDIATE IN THE OXYGENATION OF A COPPER(I) FLAVONOLATE COMPLEX

Flavonol reacts with metallic copper in the presence of 2,2'-bipyridin e to give dihydrogen and a mixture of compounds with the stoichiometri c 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 t he mixture results in the ketocarboxylatocopper(II) complex [CuII(bpy) (fla)(2-HOC(6)H(4)COCO2)], which hints at a copper-mediated oxidative cleavage of the pyranone ring in the flavonolate ligand via a 1,2-diox ethane intermediate by O-3(2).