Synthesis of Symmetrical and Unsymmetrical Thiosulfonates from Disulfides through Electrochemically Induced Disulfide Bond Metathesis and Site‐Selective Oxidation

Abstract

The anodic generation of symmetrical and unsymmetrical thiosulfonates is presented. First, the oxidation of disulfides yielding symmetrical thiosulfonates was realized. The direct synthesis is performed using a simple quasi‐divided cell design, whereby using a supporting electrolyte is unnecessary. Its principle was then expanded to the conversion of unsymmetrical disulfides that were generated in situ through metathesis of two symmetrical disulfides. This enables a direct access to unsymmetrical thiosulfonates without any pre‐functionalization or elaborate synthesis of the starting materials for the first time. The reaction scope was investigated by converting differently functionalized aliphatic and aromatic disulfides in moderate to very good yields. Furthermore, a sensitivity assessment for an improved reproducibility and a robustness screen to determine the compatibility of the reaction against functional groups were performed.

Controllable synthesis of disulfides and thiosulfonates from sodium sulfinates mediated by hydroiodic acid using ethanol and H2O as solvents

“…2 Given their good reactivity and stability, they can also be used as valuable intermediates in the synthesis of natural products as well as functional additives or auxiliary agents which benefit from their good reactivity and stability. 3 Numerous methods have been developed previously to address the unmet challenges for using disulfides and thiosulfonates because of their widespread applications. 3 In recent years, the oxidation of thiols was frequently employed for the synthesis of disulfides and thiosulfonates, 4,5 especially using visible-light irradiation or electrochemical approaches.…”

“…3 Numerous methods have been developed previously to address the unmet challenges for using disulfides and thiosulfonates because of their widespread applications. 3 In recent years, the oxidation of thiols was frequently employed for the synthesis of disulfides and thiosulfonates, 4,5 especially using visible-light irradiation or electrochemical approaches. Li and co-workers reported a simple and efficient photocatalytic method for the virtually quantitative and selective conversion of thiols into disulfides by visible-light irradiation of CdSe-QD/thiolate conjugates.…”

In situ generated HClO for the conversion of thiols and disulfides into thiosulfonates

“…17 Oxone in combination with KBr proved to be a valid alternative as shown by Natarajan et al 18 Finally, molecular oxygen can be used under photoredox catalysis conditions, 19 and very recently, also an electrochemical approach has been reported to perform such chemistry allowing formation of unsymmetrical thiosulfonates. 20…”