Thiol-copper(I) and disulfide-dicopper(I) complex O-2-reactivity leading to sulfonate-copper(II) complex or the formation of a cross-linked thioether-phenol product with phenol addition

Abstract

In order to better understand copper mediated oxidative chemistry via ligand-Cu-1/O-2 reactivity employing S-donor ligands for copper, O-2-reactivity studies of the copper(I) complexes (1 and 2, Chart 2) have been carried out with a tridentate N2S thiol ligand (1-(N-methyl-N-(2-(pyridin-2-yl)ethyl)amino)propane-2-thiol; L-SH) or its oxidized disulfide form (L-ss). Reactions of [(LCu1)-Cu-SH](+) (1) and [L-ss(CU1)(2)(X)(2)](2+) (2) with O-2 give similar to 90% and similar to 70% yields of [(LCuII)-Cu-SO3(MeOH)(2)](+) (3), respectively, where L-SO3 is S-oxygenated sulfonate; 3 was characterized by electrospray ionization (ESI) mass spectrometry and X-ray crystallography. Mimicking TyrCys galactose oxidase cofactor biogenesis, a new C-S bond is formed (within new thioether moiety L-SPhOH) from cuprous complex (both I and 2) dioxygen reactivity in the presence of 2,4-tBu(2)-phenolate. In addition, the disulfide ligand (L-SS) reacts with 2 equiv. cupric ion salts and the phenolate to efficiently give the cross-linked product L-SPhOH in high yield (>90%) under anaerobic conditions. Separately, complex [(LCuII)-Cu-SPhO(ClO4)] (4), possessing the cross-linked L-SPhOH, was characterized by ESI mass spectrometry and X-ray crystallography. (c) 2007 Elsevier Inc. All rights reserved.