Copper‐Catalyzed Aerobic Formation of Unstable Sulfinyl Radicals for the Synthesis of Sulfinates and Thiosulfonates

Abstract

Copper‐catalyzed aerobic coupling of thiols and alcohols affords sulfinates and thiosulfonates. These products are assumed to form via sulfinyl radicals which are not commonly found in oxidative coupling reactions of thiols. A reaction mechanism involving sulfinyl radicals is proposed, and mass and electron paramagnetic resonance (EPR) experimental results are provided.magnified image

Efficient electrosynthesis of sulfinic esters via oxidative cross‐coupling between alcohols and thiophenols

“…In 2016, Pan reported a copper‐catalyzed aerobic cross‐coupling of sulfonylhydrazides with alcohols, which was demonstrated as an efficient method to get access to sulfinic esters, but sulfonylhydrazides were employed instead of thiols to react with alcohols. Soon after, Jang and Zhang, respectively, realized the direct cross‐coupling of thiols with alcohols by using copper or a cobalt nanocatalyst supported on NSiO 2 ‐doped activated carbon (Co/NSiO 2 A), which significantly simplified the process . However, the transition‐metal catalysts are inevitable in these methods.…”

Sustainable Electrocatalytic Oxidant‐Free Syntheses of Thiosulfonates from Thiols

“…Very recently, new methodologies have been developed from commercially available or easily prepared substrates. By employing transition metal catalysts such as ZnCr 2 O 7 , AgNO 3 and CuI/TBD, thiosulfonates were obtained by direct oxidation of thiols, via sulfide dimerization intermediates. (Scheme B)…”

Thiosulfonates as Emerging Reactants: Synthesis and Applications

“…A very recent approach reported by the group of Jang delivers S ‐aryl arenethiosulfonates ( 7 ) in high yield in the presence of catalytic amounts of CuI and 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD) under 1 atm of oxygen (route 8) . The proposed radical mechanism involves the dimerization of a sulfinyl radical to afford a vic ‐disulfoxide ( 12 ), which immediately isomerizes to the desired symmetrical thiosulfonate ( 7 ).…”