Sulfur(IV) in Transition-Metal-Free Cross-Couplings for Biaryl Synthesis

Perry, Gregory J. P.; Yorimitsu, Hideki

doi:10.1021/acssuschemeng.1c08673

Cited by 32 publications

(8 citation statements)

References 104 publications

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“…To further understand the mechanism and factors dictating reaction outcome and regioselectivity, the rearrangements and associated transition structures (TSs) of several benzothiophene S ‐oxides were studied using density functional theory (DFT) with the M06‐2X‐D3/def2‐QZVPP (SMD=CH 2 Cl 2 )//M06‐2X‐D3/6‐31+G(d,p) (SMD=CH 2 Cl 2 ) level of theory (Scheme 5). [10] In line with previous studies from our group [7a–b, 8e] and from others [8c,d,h,i, 11] we propose a mechanism involving initial activation of the sulfoxide moiety in benzothiophene S ‐oxides as the corresponding trifluoroacetate followed by addition of phenol to give aryloxysulfonium salt or sulfurane A ; use of anisole in place of phenol gave no reaction (see Supporting Information) thus underlining the importance of the free hydroxyl group in the phenol coupling partners.…”

Section: Resultssupporting

confidence: 85%

Metal‐Free Arylation of Benzothiophenes at C4 by Activation as their Benzothiophene S‐Oxides

Bisht

Popescu

et al. 2023

Angewandte Chemie

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Benzothiophenes, activated by oxidation to the corresponding S-oxides, undergo CÀ H/CÀ H-type coupling with phenols to give C4 arylation products. While an electron-withdrawing group at C3 of the benzothiophene is important, the process operates without a directing group and a metal catalyst, thus rendering it compatible with sensitive functionalitiese.g. halides and formyl groups. Quantum chemical calculations suggest a formal stepwise mechanism involving heterolytic cleavage of an aryloxysulfur species to give a π-complex of the corresponding benzothiophene and a phenoxonium cation. Subsequent addition of the phenoxonium cation to the C4 position of the benzothiophene is favored over the addition to C3; Fukui functions predict that the major regioisomer is formed at the more electron-rich position between C3 and C4. Varied selective manipulation of the benzothiophene products showcase the synthetic utility of the metal-free arylation process.

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Section: Resultssupporting

confidence: 85%

Metal‐Free Arylation of Benzothiophenes at C4 by Activation as their Benzothiophene S‐Oxides

Bisht

Popescu

et al. 2023

Angewandte Chemie

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“…Considering the future of biaryl skeletons, we hope that new methods to prepare biaryls by underexplored mechanisms will be discovered. 83 )…”

Section: Discussionmentioning

confidence: 99%

Sulfonium-aided coupling of aromatic rings via sigmatropic rearrangement

Yorimitsu

Perry

2022

Proceedings of the Japan Academy. Ser. B: Physical and Biologic

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Biaryl synthesis continues to occupy a central role in chemical synthesis. From blockbuster drug molecules to organic electronics, biaryls present numerous possibilities and new applications continue to emerge. Transition-metal-catalyzed coupling reactions represent the gold standard for biaryl synthesis and the mechanistic steps, such as reductive elimination, are well established. Developing routes that exploit alternative mechanistic scenarios could give unprecedented biaryl structures and expand the portfolio of biaryl applications. We have developed metal-free C–H/C–H couplings of aryl sulfoxides with phenols to afford 2-hydroxy-2′-sulfanylbiaryls. This cascade strategy consists of an interrupted Pummerer reaction and [3,3] sigmatropic rearrangement. Our method enables the synthesis of intriguing aromatic molecules, including oligoarenes, enantioenriched dihetero[8]helicenes, and polyfluorobiaryls. From our successes in aryl sulfoxide/phenol couplings and a deeper understanding of sigmatropic rearrangements for biaryl synthesis, we have established related methods, such as aryl sulfoxide/aniline and aryl iodane/phenol couplings. Overall, our fundamental interests in underexplored reaction mechanisms have led to various methods for accessing important biaryl architectures.

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“…76 In the past few years, this sulfonium salt-involved system has been further extended to more reaction systems. 77…”

Section: Cleavage Of C–s Bondsmentioning

confidence: 99%