1
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Sennari G, Yamagishi H, Sarpong R. Remote C-H Amination and Alkylation of Camphor at C8 through Hydrogen-Atom Abstraction. J Am Chem Soc 2024; 146:7850-7857. [PMID: 38447162 DOI: 10.1021/jacs.4c01351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
Camphor continues to serve as a versatile chiral building block for chemical synthesis. We have developed a novel method to functionalize the camphor skeleton at C8 using an intramolecular hydrogen atom abstraction. The key advance involves the use of a camphor-derived aminonitrile, which is converted to the corresponding nitrogen-centered radical under photoredox conditions to effect the 1,5-hydrogen atom transfer at C8. The resulting carbon-centered radical at C8 was utilized in a C-H amination to access topologically complex proline derivatives. Furthermore, the total synthesis of several sesquiterpenoids was accomplished by engaging the radical generated at C8 in alkylation reactions.
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Affiliation(s)
- Goh Sennari
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- O̅mura Satoshi Memorial Institute and Graduate School of Infection Control Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Hiroki Yamagishi
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Richmond Sarpong
- Department of Chemistry, University of California, Berkeley, California 94720, United States
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2
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Sar D, Yin S, Grygus J, Rentería-Gómez Á, Garcia M, Gutierrez O. Expanding the chemical space of enol silyl ethers: catalytic dicarbofunctionalization enabled by iron catalysis. Chem Sci 2023; 14:13007-13013. [PMID: 38023494 PMCID: PMC10664506 DOI: 10.1039/d3sc04549h] [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: 08/29/2023] [Accepted: 10/19/2023] [Indexed: 12/01/2023] Open
Abstract
Enol silyl ethers are versatile, robust, and readily accessible substrates widely used in chemical synthesis. However, the conventional reactivity of these motifs has been limited to classical two electron (2-e) enolate-type chemistry with electrophilic partners or as radical acceptors in one electron (1-e) reactivity leading, in both cases, to exclusive α-monofunctionalization of carbonyls. Herein we describe a mild, fast, and operationally simple one-step protocol that combines readily available fluoroalkyl halides, silyl enol ethers, and, for the first time, hetero(aryl) Grignard reagents to promote selective dicarbofunctionalization of enol silyl ethers. From a broader perspective, this work expands the synthetic utility of enol silyl ethers and establishes bisphosphine-iron catalysis as enabling technology capable of orchestrating selective C-C bond formations with short-lived α-silyloxy radicals with practical implications towards sustainable chemical synthesis.
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Affiliation(s)
- Dinabandhu Sar
- Department of Chemistry, Texas A&M University College Station Texas 77843 USA
| | - Shuai Yin
- Department of Chemistry, Texas A&M University College Station Texas 77843 USA
| | - Jacob Grygus
- Department of Chemistry, Texas A&M University College Station Texas 77843 USA
| | | | - Melanie Garcia
- Department of Chemistry, Texas A&M University College Station Texas 77843 USA
| | - Osvaldo Gutierrez
- Department of Chemistry, Texas A&M University College Station Texas 77843 USA
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3
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Liu K, Wang Z, Künzel AN, Layh M, Studer A. Regioselective Formal β-Allylation of Carbonyl Compounds Enabled by Cooperative Nickel and Photoredox Catalysis. Angew Chem Int Ed Engl 2023; 62:e202303473. [PMID: 37141023 DOI: 10.1002/anie.202303473] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 05/03/2023] [Accepted: 05/04/2023] [Indexed: 05/05/2023]
Abstract
The Tsuji-Trost reaction between carbonyl compounds and allylic precursors has been widely used in the synthesis of natural products and pharmaceutical compounds. As the α-C-H bond is far more acidic than the β-C-H bond, carbonyl compounds undergo highly regioselective allylation at the α-position and their β-allylation is therefore highly challenging. This innate α-reactivity conversely hampers diversity, especially if the corresponding β-allylation product is targeted. Herein, we present a formal intermolecular β-C-C bond formation reaction of a broad range of aldehydes and ketones with different allyl electrophiles through cooperative nickel and photoredox catalysis. β-Selectivity is achieved via initial transformation of the aldehydes and ketones to their corresponding silyl enol ethers. The overall transformation features mild conditions, excellent regioselectivity, wide functional group tolerance and high reaction efficiency. The introduced facile and regioselective β-allylation of carbonyl compounds proceeding through cooperative catalysis allows the preparation of valuable building blocks that are difficult to access from aldehydes and ketones using existing methodology.
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Affiliation(s)
- Kun Liu
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstraße 40, 48149, Münster, Germany
| | - Zhe Wang
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstraße 40, 48149, Münster, Germany
| | - Augustinus N Künzel
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstraße 40, 48149, Münster, Germany
| | - Marcus Layh
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität, Corrensstraße 28/30, 48149, Münster, Germany
| | - Armido Studer
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstraße 40, 48149, Münster, Germany
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4
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Cao R, Liu Y, Shi X, Zheng J. Visible-light induced cross-electrophile coupling of imines and anhydrides to synthesize α-amino ketones. Chem Commun (Camb) 2023; 59:10668-10671. [PMID: 37581330 DOI: 10.1039/d3cc03028h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
α-Amino ketones are important motifs in synthetic and medicinal chemistry. Efficient methods to directly access these motifs from feasible precursors are, however, limited. Herein, a visible-light mediated reductive cross-electrophile coupling of readily available imines and anhydrides was developed. Under mild reaction conditions, the umpolung reactivity of diverse imines engaged with anhydrides gives a variety of α-amino ketones with good yields and a broad functional group compatibility. Primary mechanistic studies revealed that this transformation might proceed through a radical-radical cross coupling pathway dominantly.
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Affiliation(s)
- Renxu Cao
- Engineering Research Center of Pharmaceutical Process Chemistry, Ministry of Education, and the School of Pharmacy, East China University of Science and Technology, Shanghai 200237, P. R. China.
| | - Yu Liu
- Engineering Research Center of Pharmaceutical Process Chemistry, Ministry of Education, and the School of Pharmacy, East China University of Science and Technology, Shanghai 200237, P. R. China.
| | - Xiaoxin Shi
- Engineering Research Center of Pharmaceutical Process Chemistry, Ministry of Education, and the School of Pharmacy, East China University of Science and Technology, Shanghai 200237, P. R. China.
| | - Jun Zheng
- Engineering Research Center of Pharmaceutical Process Chemistry, Ministry of Education, and the School of Pharmacy, East China University of Science and Technology, Shanghai 200237, P. R. China.
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5
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Meger FS, Murphy JA. Recent Advances in C-H Functionalisation through Indirect Hydrogen Atom Transfer. Molecules 2023; 28:6127. [PMID: 37630379 PMCID: PMC10459052 DOI: 10.3390/molecules28166127] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 08/09/2023] [Accepted: 08/15/2023] [Indexed: 08/27/2023] Open
Abstract
The functionalisation of C-H bonds has been an enormous achievement in synthetic methodology, enabling new retrosynthetic disconnections and affording simple synthetic equivalents for synthons. Hydrogen atom transfer (HAT) is a key method for forming alkyl radicals from C-H substrates. Classic reactions, including the Barton nitrite ester reaction and Hofmann-Löffler-Freytag reaction, among others, provided early examples of HAT. However, recent developments in photoredox catalysis and electrochemistry have made HAT a powerful synthetic tool capable of introducing a wide range of functional groups into C-H bonds. Moreover, greater mechanistic insights into HAT have stimulated the development of increasingly site-selective protocols. Site-selectivity can be achieved through the tuning of electron density at certain C-H bonds using additives, a judicious choice of HAT reagent, and a solvent system. Herein, we describe the latest methods for functionalizing C-H/Si-H/Ge-H bonds using indirect HAT between 2018-2023, as well as a critical discussion of new HAT reagents, mechanistic aspects, substrate scopes, and background contexts of the protocols.
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Affiliation(s)
- Filip S. Meger
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, 16 Avinguda dels Països Catalans, 43007 Tarragona, Catalonia, Spain
| | - John A. Murphy
- Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, UK
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Hayashi R, Narita Y, Sai M. One-pot synthesis of 3-functionalized ( Z)-silyl enol ethers from 1-arylallylic alcohols by C, O-difunctionalization of dipotassio α,β-dianion intermediates. Org Biomol Chem 2023; 21:4206-4209. [PMID: 37144448 DOI: 10.1039/d3ob00199g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Previously reported syntheses of 3-functionalized silyl enol ethers using allyloxysilanes are hindered by undesirable reactions owing to retro Brook rearrangements. In this study, various 3-functionalized (Z)-silyl enol ethers were synthesized from readily available 1-arylallylic alcohols using (trimethylsilyl)methylpotassium as a base. C,O-Difunctionalization of the in situ-generated dipotassio α,β-dianion with electrophiles and silyl chlorides is key to the success of this transformation. Control experiments confirmed that the dianion has higher nucleophilicity and thermal stability than related siloxyallylpotassiums.
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Affiliation(s)
- Rikuo Hayashi
- Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
| | - Yutaka Narita
- Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
| | - Masahiro Sai
- Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
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Abstract
The fields of C-H functionalization and photoredox catalysis have garnered enormous interest and utility in the past several decades. Many different scientific disciplines have relied on C-H functionalization and photoredox strategies including natural product synthesis, drug discovery, radiolabeling, bioconjugation, materials, and fine chemical synthesis. In this Review, we highlight the use of photoredox catalysis in C-H functionalization reactions. We separate the review into inorganic/organometallic photoredox catalysts and organic-based photoredox catalytic systems. Further subdivision by reaction class─either sp2 or sp3 C-H functionalization─lends perspective and tactical strategies for use of these methods in synthetic applications.
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Affiliation(s)
- Natalie Holmberg-Douglas
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - David A Nicewicz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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8
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Le Saux E, Zanini M, Melchiorre P. Photochemical Organocatalytic Benzylation of Allylic C-H Bonds. J Am Chem Soc 2022; 144:1113-1118. [PMID: 35029387 DOI: 10.1021/jacs.1c11712] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
We report a radical-based organocatalytic method for the direct benzylation of allylic C-H bonds. The process uses nonfunctionalized allylic substrates and readily available benzyl radical precursors and is driven by visible light. Crucial was the identification of a dithiophosphoric acid that performs two distinct catalytic roles, sequentially acting as a catalytic donor for the formation of photoactive electron donor-acceptor (EDA) complexes and then as a hydrogen atom abstractor. By mastering these orthogonal radical generation paths, the organic catalyst enables the formation of benzylic and allylic radicals, respectively, to then govern their selective coupling. The protocol was also used to design a three-component radical process, which increased the synthetic potential of the chemistry.
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Affiliation(s)
- Emilien Le Saux
- ICIQ - Institute of Chemical Research of Catalonia, the Barcelona Institute of Science and Technology, Avinguda Països Catalans 16, 43007 Tarragona, Spain.,Universitat Rovira i Virgili, C/Marcel·lí Domingo s/n, 43007 Tarragona, Spain
| | - Margherita Zanini
- ICIQ - Institute of Chemical Research of Catalonia, the Barcelona Institute of Science and Technology, Avinguda Països Catalans 16, 43007 Tarragona, Spain
| | - Paolo Melchiorre
- ICIQ - Institute of Chemical Research of Catalonia, the Barcelona Institute of Science and Technology, Avinguda Països Catalans 16, 43007 Tarragona, Spain.,ICREA - Passeig Lluís Companys 23, 08010 Barcelona, Spain
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9
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Wang M, Li M, Zhang L, Song R, Yang D, Lv J. Photocatalytic Redox-Neutral Reaction of γ-Indolyl α-Keto Esters. Org Chem Front 2022. [DOI: 10.1039/d1qo01890f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The direct γ-C(sp3)-H activation of saturated α-keto esters has long been an elusive transformation. We found that photo-redox catalysis IrIII in combination with DABCO as dual hydrogen-bonding donor and organic...
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Hirata T, Ogasawara Y, Yamashita Y, Kobayashi S. α-Alkylation of Ketones with Alkenes Enabled by Photoinduced Activation of Silyl Enol Ethers in the Presence of a Small Amount of Water. Org Lett 2021; 23:5693-5697. [PMID: 34264686 DOI: 10.1021/acs.orglett.1c01824] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Under blue-light irradiation conditions with a photocatalyst [1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene], silyl enol ethers reacted with alkenes in the presence of a small amount of water to afford the α-alkylation products in good to high yields. A thiol cocatalyst was found to expand the substrate scope of the reaction.
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Affiliation(s)
- Tsubasa Hirata
- Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yoshihiro Ogasawara
- Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yasuhiro Yamashita
- Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Shu Kobayashi
- Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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11
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Adachi A, Aikawa K, Ishibashi Y, Nozaki K, Okazoe T. Bench-Stable Electrophilic Fluorinating Reagents for Highly Selective Mono- and Difluorination of Silyl Enol Ethers. Chemistry 2021; 27:11919-11925. [PMID: 34009678 DOI: 10.1002/chem.202101499] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Indexed: 11/10/2022]
Abstract
Efficient methods for the synthesis of fluorinated compounds have been intensively studied, recently. Development of practical fluorinating reagents is indispensable for this purpose. Herein, bench-stable electrophilic fluorinating reagents were synthesized as N-fluorobenzenesulfonimide (NFSI) substitutes. Reagents obtained by replacing one of the NFSI sulfonyl groups with an acyl group led to the highly selective monofluorination of silyl enol ethers with suppression of undesired overreaction, that is, difluorination. On the other hand, reagents bearing electron-withdrawing substituents at NFSI benzenesulfonyl groups efficiently facilitated the difluorination of silyl enol ethers under base-free conditions. Thus, both mono- and difluorinated target materials were prepared from the same substrate.
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Affiliation(s)
- Akiya Adachi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Kohsuke Aikawa
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Yuichiro Ishibashi
- Yokohama Technical Center, AGC Inc., 1-1 Suehiro-cho, Tsurumi-ku, Yokohama, 230-0045, Japan
| | - Kyoko Nozaki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Takashi Okazoe
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-8656, Japan.,Yokohama Technical Center, AGC Inc., 1-1 Suehiro-cho, Tsurumi-ku, Yokohama, 230-0045, Japan
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12
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Gou XY, Li Y, Luan YY, Shi WY, Wang CT, An Y, Zhang BS, Liang YM. Ruthenium-Catalyzed Radical Cyclization/meta-Selective C–H Alkylation of Arenes via σ-Activation Strategy. ACS Catal 2021. [DOI: 10.1021/acscatal.1c00359] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Xue-Ya Gou
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China
| | - Yuke Li
- Department of Chemistry and Centre for Scientific Modeling and Computation, Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Yu-Yong Luan
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China
| | - Wei-Yu Shi
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China
| | - Cui-Tian Wang
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China
| | - Yang An
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China
| | - Bo-Sheng Zhang
- College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China
| | - Yong-Min Liang
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China
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