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 .