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Hann JL, Lyall CL, Kociok-Köhn G, Faverio C, Pantoş GD, Lewis SE. Unusual Regio- and Chemoselectivity in Oxidation of Pyrroles and Indoles Enabled by a Thianthrenium Salt Intermediate. Angew Chem Int Ed Engl 2024; 63:e202405057. [PMID: 38830180 DOI: 10.1002/anie.202405057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 05/31/2024] [Accepted: 06/03/2024] [Indexed: 06/05/2024]
Abstract
A dearomative oxidation of pyrroles to Δ3-pyrrol-2-ones is described, which employs a sulfoxide as oxidant, in conjunction with a carboxylic acid anhydride and a Brønsted acid additive. 3-substituted pyrroles undergo regioselective oxidation to give the product isomer in which oxygen has been introduced at the more hindered position. Regioselectivity is rationalized by a proposed mechanism that proceeds by initial thianthrenium introduction at the less-hindered pyrrole α-position, followed by distal attack of an oxygen nucleophile and subsequent elimination of thianthrene. The same reaction conditions are also able to effect a chemoselective oxidation of indoles to indolin-3-ones and additionally of indolin-3-ones to 2-hydroxyindolin-3-ones. Here again, the regio- and chemoselectivities are rationalized through the intermediacy of a thianthrenium salt.
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Affiliation(s)
- Jodie L Hann
- Department of Chemistry, University of Bath, Bath, BA2 7AY, United Kingdom
| | - Catherine L Lyall
- Research Facilities, University of Bath, Bath, BA2 7AY, United Kingdom
| | | | - Chiara Faverio
- Department of Chemistry, University of Bath, Bath, BA2 7AY, United Kingdom
| | - G Dan Pantoş
- Department of Chemistry, University of Bath, Bath, BA2 7AY, United Kingdom
| | - Simon E Lewis
- Department of Chemistry, University of Bath, Bath, BA2 7AY, United Kingdom
- Institute of Sustainability and Climate Change, University of Bath, Bath, BA2 7AY, United Kingdom
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2
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Wakabayashi R, Wang S, Kurogi T, Yorimitsu H. Arylation of benzazoles at the 4 positions by activation of their 2-methylsulfinyl groups. Chem Commun (Camb) 2024; 60:6166-6169. [PMID: 38804671 DOI: 10.1039/d4cc01918k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Treatment of 2-methylsulfinylbenzazoles with triflic anhydride in the presence of phenols yields the corresponding 4-(p-hydroxyphenyl)-2-methylsulfanylbenzazoles. This regioselective dehydrative C-H/C-H coupling arylation represents a rare example of functionalizations on the benzene rings of benzo-fused azoles.
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Affiliation(s)
- Ryota Wakabayashi
- Department of Chemistry Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Shuo Wang
- Department of Chemistry Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Takashi Kurogi
- Department of Chemistry Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Hideki Yorimitsu
- Department of Chemistry Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
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3
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Kobayashi A, Tabata S, Yoshida S. Highly substituted benzo[ b]furan synthesis through substituent migration. Chem Commun (Camb) 2024; 60:4545-4548. [PMID: 38578172 DOI: 10.1039/d4cc01192a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2024]
Abstract
An unusual benzofuran synthesis from 2,6-disubstituted phenols and alkynyl sulfoxides is disclosed. Various highly substituted benzofurans were synthesized via the charge-accelerated [3,3]-sigmatropic rearrangement and subsequent substituent migration. Multiaryl-substituted benzofurans and fully substituted benzofurans were prepared on the basis of the unique reaction mechanism.
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Affiliation(s)
- Akihiro Kobayashi
- Department of Biological Science and Technology, Faculty of Advanced Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan.
- Laboratory of Chemical Bioscience, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-0062, Japan
| | - Shinya Tabata
- Department of Biological Science and Technology, Faculty of Advanced Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan.
| | - Suguru Yoshida
- Department of Biological Science and Technology, Faculty of Advanced Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan.
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Ye S, Wang H, Liang G, Hu Z, Wan K, Zhang L, Peng B. ortho-Cyanomethylation of aryl fluoroalkyl sulfoxides via a sulfonium-Claisen rearrangement. Org Biomol Chem 2024; 22:1495-1499. [PMID: 38293848 DOI: 10.1039/d3ob02102e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
We hereby report the ortho-cyanomethylation of aryl fluoroalkyl sulfoxides with acetonitrile through a sulfonium-Claisen-type rearrangement. This reaction enables the incorporation of two valuable functional groups, such as the cyanomethyl group and the fluoroalkylthio group, into arenes. Remarkably, fluoroalkylthio groups, such as SCFH2 and SCF2H, bearing active hydrogen, are well tolerated by the reaction. The success of the reaction relies on the use of an excess amount of acetonitrile and the electronegative effect of fluoroalkyl substituents, both of which promote the electrophilic assembly of sulfoxides with acetonitrile. Consequently, the sulfonium-Claisen rearrangement reaction tolerates a wide variety of fluoroalkyl sulfoxides bearing functional groups including halides, nitriles, ketones, sulfones, and amides, which are appealing for subsequent elaboration and exploration.
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Affiliation(s)
- Sheng Ye
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Zhejiang Normal University, Jinhua 321004, China.
| | - Huanhuan Wang
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Zhejiang Normal University, Jinhua 321004, China.
| | - Guoqing Liang
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Zhejiang Normal University, Jinhua 321004, China.
| | - Zhengkai Hu
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Zhejiang Normal University, Jinhua 321004, China.
| | - Kun Wan
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Zhejiang Normal University, Jinhua 321004, China.
| | - Lei Zhang
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Zhejiang Normal University, Jinhua 321004, China.
| | - Bo Peng
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Zhejiang Normal University, Jinhua 321004, China.
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Higuchi K, Yamamoto K, Nakamura S, Naruse H, Ito M, Sugiyama S. Preparation of Alkyl Di( p-tolyl)sulfonium Salts and Their Application in Metal-Free C(sp 3)-C(sp 3) and C(sp 3)-C(sp 2) Bond Formations. Org Lett 2023; 25:3766-3771. [PMID: 37167562 DOI: 10.1021/acs.orglett.3c01233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Alkyldiarylsulfonium salts were synthesized by a combination of active sulfonium species, prepared through the activation of diarylsulfoxide, and alkyl nucleophiles. The isolated sulfonium salts were subjected to the allylation and cyclopropanation of the active methylene compounds and metal-free C(sp3)-C(sp2) couplings via oxyallyl cation intermediates under mild conditions. The series of reactions included an umpolung strategy for the coupling of alkyl nucleophiles and metal-free C-C bond formation using sulfonium salts.
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Affiliation(s)
- Kazuhiro Higuchi
- Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
| | - Kai Yamamoto
- Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
| | - Shunsuke Nakamura
- Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
| | - Haruka Naruse
- Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
| | - Motoki Ito
- Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
| | - Shigeo Sugiyama
- Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
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Li X, Li Y, Yang J, Shi H, Ai Z, Han C, He J, Du Y. Synthesis of 3-SCF 2H-/3-SCF 3-chromones via Interrupted Pummerer Reaction/Intramolecular Cyclization Mediated by Difluoromethyl or Trifluoromethyl Sulfoxide and Tf 2O. Org Lett 2022; 24:7216-7221. [PMID: 36148991 DOI: 10.1021/acs.orglett.2c03017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reaction of alkynyl aryl ketones bearing an o-methoxy group with difluoromethyl sulfoxide in the presence of Tf2O was found to conveniently afford the corresponding 3-SCF2H-substituted chromones. The combining use of difluoromethyl sulfoxide/Tf2O could represent the first reagents system that can introduce the biologically important SCF2H moiety under base-free conditions via an interrupted Pummerer reaction. The same protocol could also be applied to the synthesis of 3-SCF3-substituted chromones by replacing difluoromethyl sulfoxide with trifluoromethyl sulfoxide and CH3CN with toluene.
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Affiliation(s)
- Xuemin Li
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Yue Li
- State Key Laboratory of Metastable Materials Science and Technology, Hebei Key Laboratory of Nano-biotechnology, Yanshan University, Qinhuangdao 066004, P.R. China
| | - Jingyue Yang
- State Key Laboratory of Metastable Materials Science and Technology, Hebei Key Laboratory of Nano-biotechnology, Yanshan University, Qinhuangdao 066004, P.R. China
| | - Haofeng Shi
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Zhenkang Ai
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Chi Han
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Jiaxin He
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Yunfei Du
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
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An Unexpected Reaction between Diaryliodonium Salts and DMSO. ORGANICS 2022. [DOI: 10.3390/org3030020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Diaryliodonium salts are useful arylating reagents that have been exploited widely. In this Communication, we demonstrate that heating diphenyliodonium triflate in the solvent DMSO leads to an unexpected arylation reaction. It is postulated that arylation of DMSO at oxygen, followed by a thia-Sommelet–Hauser rearrangement, leads to the formation of 2-thiomethylphenols. More substituted diaryliodonium salts and cyclic diaryliodonium salts are shown to be more stable and less likely to react with DMSO. In conclusion, when using iodonium salts dissolved in DMSO, beware of side-reactions.
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Liang Y, Peng B. Revisiting Aromatic Claisen Rearrangement Using Unstable Aryl Sulfonium/Iodonium Species: The Strategy of Breaking Up the Whole into Parts. Acc Chem Res 2022; 55:2103-2122. [PMID: 35861672 DOI: 10.1021/acs.accounts.2c00263] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
ConspectusSince Ludwig Claisen's discovery of the sigmatropic rearrangement of allyl aryl ethers in 1912, aromatic Claisen rearrangement has continuously attracted the attention of both experimental and theoretical chemists. Over more than a century of growth, this protocol has proven to be a practical and powerful synthetic tool in many aspects. However, the reaction scope has long been limited to aryl ethers and their S or N analogs until the serendipitous discovery of aromatic iodonium-Claisen rearrangement by Oh et al. in 1988 and the development of aromatic sulfonium-Claisen rearrangement by Kita et al. in 2004. Unlike traditional Claisen rearrangements, these hypervalent-bonding-based Claisen-type rearrangements can be performed by simply mixing electrophilically activated aryl sulfoxides/iodanes with certain nucleophiles to directly deliver rearrangement products. In addition to the simple operation, remarkable features, such as readily available substrates, valuable products and intriguing rearrangement patterns, have led to a dramatic resurgence of this rearrangement chemistry.In this Account, we summarize our recent works on developing new aromatic rearrangement modes using sulfonium/iodonium reagents. Interestingly, the program started with an accidental discovery that aryl sulfoxides could be coupled with alkyl nitriles in the presence of Tf2O and base. Mechanistic studies reveal that the reaction proceeds in three major steps, including the Tf2O-triggered assembly of both coupling partners, base-promoted deprotonation of in situ-generated aryl sulfonium-imine species leading to a key rearrangement precursor called aryl sulfonium-ketenimine species, and subsequent facile and rapid [3,3]-rearrangement. On the basis of the mechanistic underpinning, we divided the one-step operation into two steps called the "assembly/deprotonation" protocol for constructing unstable rearrangement precursors. Most notably, the switch from the commonly used one-step to mechanism-based multiple-step manipulation, which can be termed "breaking up the whole into parts", not only enables the independent control of each step of the reaction, thus significantly expanding the accessible synthetic scope, but also raises opportunities for developing new rearrangement patterns. For example, the "assembly/deprotonation" protocol has also been applied to the development of [5,5]-rearrangement of aryl sulfoxides and the asymmetric rearrangement of aryl iodanes, thus enabling the unprecedented regio- and stereocontrol of the rearrangement process. Furthermore, the "breaking up the whole into parts" thinking triggered us to merge the Morita-Baylis-Hillman (MBH) reaction into the rearrangement process to accomplish Z-selective MBH-type [3,3]-rearrangement of α,β-unsaturated nitriles and E-selective MBH-type [3,3]-rearrangement of α,β-unsaturated 2-oxazolines, which expands the scope of rearrangement partners to include α,β-unsaturated carbonyls. In addition, the impressive rapidity of the rearrangement process found in our initial discovery has also been recognized as a congestion-acceleration effect, which was further utilized to forge the rapid ortho-cyanoalkylative rearrangement of aryl iodanes, and thus leading to the first dearomatization of aryl iodanes. We anticipate that our protocols and ideas behind the methods will be complementary to the traditional thinking of the aromatic Claisen rearrangement.
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Affiliation(s)
- Yuchen Liang
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Zhejiang Normal University, 688 Yingbin Road, Jinhua321004, China
| | - Bo Peng
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Zhejiang Normal University, 688 Yingbin Road, Jinhua321004, China
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YORIMITSU H, PERRY GJP. Sulfonium-aided coupling of aromatic rings via sigmatropic rearrangement. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2022; 98:190-205. [PMID: 35400695 PMCID: PMC9071926 DOI: 10.2183/pjab.98.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 01/19/2022] [Indexed: 06/14/2023]
Abstract
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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Affiliation(s)
- Hideki YORIMITSU
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Gregory J. P. PERRY
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, Japan
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