Copper(II)-Catalyzed Disulfide ScissionStepwise Aerobic Oxidative Cleavage to Sulfinate and Sulfonate and Reductive Anaerobic Cleavage to Thiols

Abstract

The Cu­(II)-catalyzed oxidative and reductive cleavage of the disulfide bond of <i>N</i>-(2-(2-(2-picolinamido)­phenyl)­disulfanyl)­phenyl)­picolinamide, <b>L</b>, is reported for the first time. Aerobic oxidation with Cu­(II) gives complete oxidation of S–S bond to sulfonates, whereas Ag­(I) gives only partial oxidation up to sulfinates, in the absence of any other oxidizing agent, in tetrahydrofuran/water solution. The <i>in situ</i> generated sulfonate product forms a thermally stable, two-dimensional H-bonded polymeric complex with Cu­(II) ions in two polymorphic forms. <b>L</b> in the presence of Cu­(II), in an inert atmosphere, results in a reductive cleavage of the disulfide bond and an <i>in situ</i> formation of a new C–S bond. The latter forms a unique tetranuclear complex with Cu­(II) employing deprotonated amide groups and bridging thiol and chloride atoms. The disulfide precursor and the products were characterized by X-ray crystallography and spectroscopic techniques