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Miyamoto Y, Murakami S, Sumida Y, Hirai G, Ohmiya H. Radical C-Glycosylation Using Photoexcitable Unprotected Glycosyl Borate. Chemistry 2024; 30:e202402256. [PMID: 38980084 DOI: 10.1002/chem.202402256] [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: 06/12/2024] [Revised: 07/08/2024] [Accepted: 07/09/2024] [Indexed: 07/10/2024]
Abstract
We have developed radical C-glycosylation using photoexcitable unprotected glycosyl borate. The direct excitation of glycosyl borate under visible light irradiation enabled the generation of anomeric radical without any photoredox catalysts. The in situ generated anomeric radical was applicable to the radical addition such as Giese-type addition and Minisci-type reaction to introduce alkyl and heteroaryl groups at the anomeric position. In addition, the radical-radical coupling between the glycosyl borate and acyl imidazolide provided unprotected acyl C-glycosides.
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Affiliation(s)
- Yusuke Miyamoto
- Institute for Chemical Research Kyoto University, 611-0011, Gokasho, Uji, Kyoto, Japan
| | - Sho Murakami
- Institute for Chemical Research Kyoto University, 611-0011, Gokasho, Uji, Kyoto, Japan
| | - Yuto Sumida
- Laboratory of Chemical Bioscience, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 101-0062, Kanda- Surugadai, Chiyoda-ku Tokyo, Japan
| | - Go Hirai
- Graduate School of Pharmaceutical Sciences, Kyushu University, 812-8582, Maidashi, Higashiku, Fukuoka, Japan
| | - Hirohisa Ohmiya
- Institute for Chemical Research Kyoto University, 611-0011, Gokasho, Uji, Kyoto, Japan
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Bisoyi A, Tripathy AR, Behera A, Yatham VR. α-C(sp 3)-H (Hetero)Arylation of Thioethers Enabled by Photoexcited Triplet Ketone Catalysis. J Org Chem 2024; 89:12540-12546. [PMID: 39163310 DOI: 10.1021/acs.joc.4c01480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/22/2024]
Abstract
We report herein α-C(sp3)-H (hetero)arylation of thioethers enabled by dual nickel and photoexcited triplet ketone catalysis. The mild reaction conditions of this protocol tolerate a variety of functional groups and further facilitate the late-stage functionalization of biologically relevant molecules to afford corresponding products in moderate to good yields. Preliminary mechanistic studies suggest that the generation of the α-thioalkyl radical takes place through a hydrogen atom transfer (HAT) event, which is involved in the rate-limiting step and in the nickel cycle, the reaction of the α-thioalkyl radical with Ni(0)Ln catalyst followed by oxidative addition of aryl bromide is the dominating pathway. Furthermore, the heteroaromatic benzylic thioethers can also be achieved from the corresponding reduced 4-cyano pyridine derivatives in the presence of a ketone catalyst through a radical-radical coupling reaction without metal. The increased yield of the products in the presence of DABCO might indicate a higher rate of α-thioalkyl radical formation from thioethers through the HAT event by DABCO radical cation.
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Affiliation(s)
- Akash Bisoyi
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram 695551, India
| | - Alisha Rani Tripathy
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram 695551, India
| | - Amit Behera
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram 695551, India
| | - Veera Reddy Yatham
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram 695551, India
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Sivaraj C, Muthuvel K, Udayan AT, Premkumar E, Gandhi T. Facile Cleavage of Activated Ketones: An Access to Thioethers via In Situ Generation of Anhydrides by Pummerer-Type Rearrangement. J Org Chem 2024; 89:7020-7026. [PMID: 38664860 DOI: 10.1021/acs.joc.4c00407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
Herein, we report an oxygen insertion in activated ketones from simple inorganic carbonates for the synthesis of symmetric aromatic anhydrides. For the first time, Li2CO3 acts as an oxygen source and the in situ generated symmetric aromatic anhydrides undergo Pummerer-type rearrangement to access α-benzoyloxy-thioethers. Attractively, this protocol occurs under metal-, ligand-, and oxidant-free conditions and is compatible with a wide range of substrates. Control experiments reveal the reaction pathway.
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Affiliation(s)
- Chandrasekaran Sivaraj
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore 632014, Tamil Nadu, India
| | - Karthick Muthuvel
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore 632014, Tamil Nadu, India
| | - Ajay Thonipalliyalil Udayan
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore 632014, Tamil Nadu, India
| | - Egambaram Premkumar
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore 632014, Tamil Nadu, India
| | - Thirumanavelan Gandhi
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore 632014, Tamil Nadu, India
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Sivaraj C, Maiti D, Gandhi T. Photo-Catalyzed Acyl Azolium Promoted Selective α-C(sp 3 )-H Acylation of Acetone via HAT: Access to Thermodynamically Less Favoured (Z)-α,β-Unsaturated Ketones. Chemistry 2024; 30:e202303626. [PMID: 37997552 DOI: 10.1002/chem.202303626] [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: 11/02/2023] [Revised: 11/20/2023] [Accepted: 11/21/2023] [Indexed: 11/25/2023]
Abstract
Mono α-acylation of acetone has been achieved for the first time by reacting with bench-stable acyl azolium salts under violet-LED light at room temperature. The intermolecular hydrogen atom transfer (HAT) from acetone to triplet state of azolium salts under violet LED irradiation resulted in thermodynamically less favourable (Z)-α,β-unsaturated ketones with up to 99 : 1 selectivity via C-C bond formation. This compelling protocol access the desired α-C(sp3 )-H acylation product under metal-, ligand- and oxidant-free conditions on a wide range of substrates.
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Affiliation(s)
- Chandrasekaran Sivaraj
- Department of Chemistry, Vellore Institute of Technology, Vellore, 632014, Tamil Nadu, India
| | - Debabrata Maiti
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Thirumanavelan Gandhi
- Department of Chemistry, Vellore Institute of Technology, Vellore, 632014, Tamil Nadu, India
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Cao J, Zhu JL, Scheidt KA. Photoinduced cerium-catalyzed C-H acylation of unactivated alkanes. Chem Sci 2023; 15:154-159. [PMID: 38131082 PMCID: PMC10732008 DOI: 10.1039/d3sc05162e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 11/09/2023] [Indexed: 12/23/2023] Open
Abstract
Ketones are ubiquitous motifs in the realm of pharmaceuticals and natural products. Traditional approaches to accessing these species involve the addition of metal reagents to carboxyl compounds under harsh conditions. Herein, we report a cerium-catalyzed acylation of unactivated C(sp3)-H bonds using bench-stable acyl azolium reagents under mild and operationally-friendly conditions. This reaction exhibits excellent generality, accommodating a wide range of feedstock chemicals such as cycloalkanes and acyclic compounds as well as facilitating the late-stage functionalization of pharmaceuticals. We demonstrate further applications of our strategy with a three-component radical relay reaction and an enantioselective N-heterocyclic carbene (NHC) and cerium dual-catalyzed reaction.
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Affiliation(s)
- Jing Cao
- Department of Chemistry, Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Joshua L Zhu
- Department of Chemistry, Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Karl A Scheidt
- Department of Chemistry, Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
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Rourke MJ, McGill MJ, Yang D, Farnam EJ, Zhu JL, Scheidt KA. Photoredox-Catalyzed Radical-Radical Coupling of Potassium Trifluoroborates with Acyl Azoliums. Synlett 2023; 34:2175-2180. [PMID: 38948905 PMCID: PMC11210951 DOI: 10.1055/s-0041-1738448] [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] [Indexed: 07/02/2024]
Abstract
Potassium trifluoroborates have gained significant utility as coupling partners in organic synthesis, particularly in the Suzuki-Miyaura coupling reaction. Recently, they have also been used as radical precursors under oxidative conditions to generate carbon-centered radicals. These versatile reagents have found new applications in photoredox catalysis, including radical substitution, conjugate addition reactions, and transition metal dual catalysis. In addition, this photomediated redox neutral process has enabled radical-radical coupling with persistent radicals in the absence of a metal, and this process remains to be fully explored. In this study, we report the radical-radical coupling of benzylic potassium trifluoroborate salts with isolated acyl azolium triflates, which are persistent radical precursors. The reaction is catalyzed by an organic photocatalyst and forms isolable tertiary alcohol species. These compounds can be transformed into a range of substituted ketone products by simple treatment with a mild base.
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Affiliation(s)
- Michael J. Rourke
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (USA
| | - Matthew J. McGill
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (USA
| | - Daniel Yang
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (USA
| | - Emelia J. Farnam
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (USA
| | - Joshua L. Zhu
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (USA
| | - Karl A. Scheidt
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (USA
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