Iron(III)-Catalyzed Radical Cross-Coupling of Thiols with Sodium Sulfinates: A Facile Access to Thiosulfonates

Abstract

A convenient and efficient synthesis of symmetrical and asymmetric thiosulfonates from thiols and sodium sulfinates is reported. The protocol involves iron(III)-catalyzed formation of sulfenyl and sulfonyl radicals in situ under aerobic conditions and their subsequent cross-coupling to afford thiosulfonates in 83-96% yield. The utilization of readily available, nontoxic, and inexpensive iron(III) as a catalyst and atmospheric oxygen as an oxidant is within the confines of green and sustainable chemistry.

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

“…Symmetrical thiosulfonates can be prepared by oxidative dimerization of thiols, [16–21] oxidation of disulfides, [16,22–26] reduction of sulfonyl chlorides [27–32] or the decomposition of sulfonyl hydrazines [22,33,34] . The generation of unsymmetrical thiosulfonates is more challenging and can be accomplished for example by cross‐coupling of sodium sulfinates with thiols, [35,36] disulfides [37–40] or N ‐arylthiosuccinimides [41,42] . Alternatively, they can be synthesized by reaction of thiols with sulfonyl hydrazines [43–45] or by the addition of thiols to sulfonyl halides through a nucleophilic substitution [46–48] .…”

Thiosulfonates as Emerging Reactants: Synthesis and Applications

“…Alternatively,i n2 016a nF eCl 3 -catalyzedr adical crosscoupling of thiols (1)w ith sodium sulfinates (5)u sing air as oxidant was proposed for the preparation of both symmetrical andu nsymmetrical thiosulfonates (7)( Scheme41, route2 ). [114] Despite high yields anda shortr eactiont ime,u nfortunatelyt his route specifically requires hazardous N,N-dimethylformamide as solvent,a lthough the polar aprotic solvent screening was not intensive.T he PMI is also substantially higher comparedt ot hat of the Taniguchic onditions, mainly due to the solvent. Sarkar et al identifiedt rimethyl(phenyl)ammonium tribromide (PTAB) as an effectivec oupling reagent for the oxidative coupling of sodium sulfinates (5)a nd thiols (1)( Scheme 41 Scheme 40.…”

“…[130] They employed ah eterogeneous recyclable Pd/ ZrO 2 photocatalysta nd propose ar adical decomposition mechanism (Scheme 50) in which the Pd catalyst generates as ulfonylr adical (111)f rom the sulfonyl hydrazide (12) via hydrogen atom abstraction under visible light illumination. This is then followed by the releaseo fN 2 from intermediate 113.S ubsequent reductiono fs ulfonylr adical (111)o nt he H-Pd surface generates watera nd as ulfinyl radical (114). As ulfenyl radical (107)i sf ormed via ac onsecutive reduction, which finally reacts with another sulfonyl radical 111 to generate the desired thiosulfonate (7).…”

“…Although the role of NH 4 BF 4 is not clear and hazardous N , N ‐dimethylacetamide (DMA) is employed, the PMI and PMI RRC are rather low compared to the previously discussed methods (Scheme , Scheme , and Scheme ). Alternatively, in 2016 an FeCl 3 ‐catalyzed radical cross‐coupling of thiols ( 1 ) with sodium sulfinates ( 5 ) using air as oxidant was proposed for the preparation of both symmetrical and unsymmetrical thiosulfonates ( 7 ) (Scheme , route 2) . Despite high yields and a short reaction time, unfortunately this route specifically requires hazardous N , N ‐dimethylformamide as solvent, although the polar aprotic solvent screening was not intensive.…”

Sustainable synthesis of thiosulfonates and disulfides by molybdenum-catalyzed selective oxidation of thiols

“…2 In addition, they can also be used as valuable building blocks for various organic transformations. Accordingly, numerous efforts have been devoted to synthesize thiosulfonates and disulfides, such as cross-coupling reactions of sodium sulfinates with disulfides (or sulfonyl hydrazides with thiols) 3 and reductive coupling of sulfonyl compounds ( e.g. , sulfonyl hydrazides, sulfonyl chlorides and sodium sulfinates), 4 and additionally several methods that rely on cross-coupling.…”