Redox‐Divergent Construction of (Dihydro)thiophenes with DMSO

Abstract

Thiophene-based rings are one of the most widely used building blocks for the synthesis of sulfur-containing molecules.I nspired by the redox diversity of these features in nature,w ed emonstrate herein ar edox-divergent construction of dihydrothiophenes,thiophenes,and bromothiophenes from the respective readily available allylic alcohols,d imethyl sulfoxide (DMSO), and HBr.T he redox-divergent selectivity could be manipulated mainly by controlling the dosage of DMSO and HBr.M echanistic studies suggest that DMSO simultaneously acts as an oxidant and as ulfur donor.T he synthetic potentials of the products as platform molecules were also demonstrated by various derivatizations,i ncluding the preparation of bioactive and functional molecules.

Disproportionation-Inspired Construction of Highly Functionalized Bicyclo[3.2.1]octanes

“…On the basis of the aforementioned observations and previous reports, a plausible mechanism for the construction of highly functionalized bicyclo[3.2.1]­octane is shown in Figure e. Initially, allylic alcohol 1 proceeds through dehydration to produce diene intermediate 3 .…”

“…The addition of water had no obvious effect on the reaction (entry 14). In the presence of I 2 and DMSO, the formation of thiophene and a homo-Diels–Alder cycloaddition product from a diene intermediate was observed . Considering that the diene produced from 1a may polymerize, a radical inhibitor was added, but no desired product was obtained in the presence of BHT (entry 15).…”

“…This suggests that both diene 3 and enone 4 are key intermediates for the formation of bicyclo[3.2.1]­octane. According to our previous work, an allylic alcohol could undergo dehydration easily to produce a diene. To determine the generation pathway of enone, a related experiment was conducted (Figure b).…”

Cobalt(III)-Catalyzed and DMSO-Involved Allylation of 1,3-Dicarbonyl Compounds with Alkenes

“…On the other hand, dimethyl sulfoxide (DMSO) as a cheap and commercially available polar aprotic solvent has recently attracted much attention owing to its unique reactivity. More importantly, it also serves as a versatile precursor of functional groups, such as −O, −S, −SMe, −CH 2 SMe, −SO 2 Me, −Me, −CN, and −CHO . Recently, we and Guo groups independently reported a cobalt­(III)-catalyzed and DMSO-involved C–H activation reactions, in which DMSO was employed as the carbon source with activation of K 2 S 2 O 8 .…”

Metal-Free C–S Bond Formation in Elemental Sulfur and Cyclobutanol Derivatives: The Synthesis of Substituted Thiophenes

“… Thiophenes can serve as useful and valuable building blocks for the assembly of molecular complexity. , Conventional routes for the synthesis of substituted thiophenes involve cyclization of substrates with sulfurating reagents and functionalization of the preconstructed thiophene nucleus . The former method mainly includes two or three starting materials. ,, Despite the versatility and overall efficiency of this transformation, the thiolation of the cyclobutanols with sulfur powder is less explored. Inspired by these elegant works, we envisioned that the release of strain of cyclobutanols might offer an opportunity for the synthesis of thiophenes via metal-free C–C bond cleavage to construct C–S bonds by ring opening and/or aromatization (Scheme c).…”