Thiol-copper(I) and disulfide–dicopper(I) complex O2-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–CuI/O2 reactivity employing S-donor ligands for copper, O2-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; LSH) or its oxidized disulfide form (LSS). Reactions of [LSHCuI]+ (1) and [LSS(CuI)2(X)2]2+ (2) with O2 give ∼90% and ∼70% yields of [LSO3CuII(MeOH)2]+ (3), respectively, where LSO3 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 LSPhOH) from cuprous complex (both 1 and 2) dioxygen reactivity in the presence of 2,4-tBu2-phenolate. In addition, the disulfide ligand (LSS) reacts with 2equiv. cupric ion salts and the phenolate to efficiently give the cross-linked product LSPhOH in high yield (>90%) under anaerobic conditions. Separately, complex [LSPhOCuII(ClO4)] (4), possessing the cross-linked LSPhOH, was characterized by ESI mass spectrometry and X-ray crystallography.