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Ma B, Gong Y, Long Y, Chen Z, Yuan Y, Yang J. Synthesis of Acylhydroquinones through Visible-Light-Mediated Hydroacylation of Quinones with α-Keto Acids. J Org Chem 2024; 89:1669-1680. [PMID: 38204383 DOI: 10.1021/acs.joc.3c02361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
A mild and eco-friendly visible-light-induced protocol for the hydroacylation of quinones with α-keto acids has been developed. In the absence of any catalyst or additive, the decarboxylative hydroacylation proceeded smoothly under visible-light irradiation at room temperature. A wide range of quinones and α-keto acids were well-tolerated and afforded hydroacylation products up to 88% isolated yield. The reaction can be scaled up, and the induced groups are useful for further synthetic applications. Preliminarily, mechanistic studies indicated that photoactive quinones absorb visible light to facilitate the transformation.
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Affiliation(s)
- Ben Ma
- College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China
| | - Yawen Gong
- College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China
| | - Yun'e Long
- College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China
| | - Zhiyong Chen
- College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China
| | - Yong Yuan
- College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China
| | - Jingya Yang
- College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China
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Luo XL, Ye DD, Zheng J, Chen DN, Chen LN, Li L, Li SH, Xia PJ. Photocatalytic Unsymmetrical Diamination of Styrenes, Indoles, and Benzofurans Facilitated by Benzotriazolyl and Iminyl Radicals. Org Lett 2024. [PMID: 38193458 DOI: 10.1021/acs.orglett.3c04148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
Utilizing energy transfer catalysis, this research employed the bifunctional reagents benzotriazole carboxylic acid oxime esters to simultaneously generate benzotriazole and imine radicals. The synthesis of two distinct C-N bonds in a single conversion is showcased through radical addition and radical-radical cross-coupling processes between benzotriazole carboxylic acid oxime ester and olefins. This process facilitates the intermolecular two-component unsymmetrical diamination reaction of olefins. Using this approach, more than 40 benzotriazole-containing molecules were successfully synthesized using styrene, indole, and benzofuran as acceptors, with yields ranging from moderate to excellent.
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Affiliation(s)
- Xue-Ling Luo
- School of Chemistry and Pharmaceutical Sciences, State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Guangxi Normal University, Guilin, Guangxi 541004, P. R. China
| | - Dan-Dan Ye
- School of Chemistry and Pharmaceutical Sciences, State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Guangxi Normal University, Guilin, Guangxi 541004, P. R. China
| | - Judun Zheng
- Molecular Diagnosis and Treatment Center for Infectious Diseases, Dermatology Hospital, Southern Medical University, Guangzhou, Guangdong 510091, P. R. China
| | - Dan-Na Chen
- School of Chemistry and Pharmaceutical Sciences, State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Guangxi Normal University, Guilin, Guangxi 541004, P. R. China
| | - Li-Ning Chen
- School of Chemistry and Pharmaceutical Sciences, State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Guangxi Normal University, Guilin, Guangxi 541004, P. R. China
| | - Lin Li
- The Second Affiliated Hospital of Hunan University of Traditional Chinese Medicine, Hunan University of Chinese Medicine, Changsha, Hunan 410005, P. R. China
| | - Shu-Hui Li
- School of Chemistry and Pharmaceutical Sciences, State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Guangxi Normal University, Guilin, Guangxi 541004, P. R. China
| | - Peng-Ju Xia
- School of Chemistry and Pharmaceutical Sciences, State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Guangxi Normal University, Guilin, Guangxi 541004, P. R. China
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Wang L, Shi M, Chen X, Su N, Luo W, Zhang X. Generation of Aromatic N-Heterocyclic Radicals for Functionalization of Unactivated Alkenes. Angew Chem Int Ed Engl 2023; 62:e202314312. [PMID: 37946626 DOI: 10.1002/anie.202314312] [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: 09/24/2023] [Revised: 10/30/2023] [Accepted: 11/09/2023] [Indexed: 11/12/2023]
Abstract
Nitrogen-centered radicals (NCRs) have been widely recognized as versatile synthetic intermediates for the construction of nitrogen containing molecules of high value. As such, there has been a long-standing interest in the field of organic synthesis to develop novel nitrogen-based radicals and explore their inherent reactivity. In this study, we present the generation of aromatic N-heterocyclic radicals and their application in a novel and diverse functionalization of unactivated alkenes. Bench-stable aromatic N-heterocyclic pyridinium salts were employed as crucial NCR precursors, which enabled the efficient conversion of various unactivated alkenes into medicinally relevant alkylated N-heterocyclic amines. This approach offers an unexplored retrosynthetic disconnection for the synthesis of related molecules that commonly possess therapeutic value. Furthermore, this platform can be extended to the synthesis of densely functionalized heterocyclic amines by utilizing disulfides and diethyl bromomalonate as radical quenchers. Mechanistic investigations indicate an energy transfer (EnT) pathway involving the formation of a transient aromatic N-heterocyclic radical, radical addition to unactivated alkenes, and subsequent generation of the amination product through either hydrogen atom transfer (HAT) or radical addition processes.
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Affiliation(s)
- Lu Wang
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
| | - Minxu Shi
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
| | - Xiaoping Chen
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
| | - Nicholas Su
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
| | - Weili Luo
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
| | - Xiaheng Zhang
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
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Li M, Zhang T, Shi Y, Duan C. Harnessing Radicals in Confined Supramolecular Environments Made Possible by MOFs. CHEM REC 2023; 23:e202300158. [PMID: 37310416 DOI: 10.1002/tcr.202300158] [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: 04/30/2023] [Revised: 05/27/2023] [Indexed: 06/14/2023]
Abstract
Researching and utilizing radical intermediates in organic synthetic chemistry have innovated discoveries in methodology and theory. Reactions concerning free radical species opened new pathways beyond the frame of the two-electron mechanism while commonly characterized as rampant processes lacking selectivity. As a result, research in this field has always focused on the controllable generation of radical species and determining factors of selectivity. Metal-organic frameworks (MOFs) have emerged as compelling candidates as catalysts in radical chemistry. From a catalytic point of view, the porous nature of MOFs entails an inner phase for the reaction that could offer possibilities for the regulation of reactivity and selectivity. From a material science perspecti ve, MOFs are organic-inorganic hybrid materials that integrate functional units in organic compounds and complex forms in the tunable long-ranged periodic structure. In this account, we summarized our progress in the application of MOFs in radical chemistry in three parts: (1) The generation of radical species; (2) The weak interactions and site selectivity; (3) Regio- and stereo-selectivity. The unique role of MOFs play in these paradigms is demonstrated in a supramolecular narrative through the analyses of the multi-constituent collaboration within the MOF and the interactions between MOFs and the intermediates during the reactions.
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Affiliation(s)
- Mochen Li
- State Key Laboratory of Fine Chemicals, School of Chemical Engineering, School of Chemistry, Dalian University of Technology, Dalian, 116024, P. R. China
| | - Tiexin Zhang
- State Key Laboratory of Fine Chemicals, School of Chemical Engineering, School of Chemistry, Dalian University of Technology, Dalian, 116024, P. R. China
| | - Yusheng Shi
- State Key Laboratory of Fine Chemicals, School of Chemical Engineering, School of Chemistry, Dalian University of Technology, Dalian, 116024, P. R. China
| | - Chunying Duan
- State Key Laboratory of Fine Chemicals, School of Chemical Engineering, School of Chemistry, Dalian University of Technology, Dalian, 116024, P. R. China
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Nguyen QH, Um TW, Shin S. α-Carbonyl Radicals from N-Enoxybenzotriazoles: De Novo Synthesis of 9-Phenanthrols. Org Lett 2022; 24:8337-8342. [DOI: 10.1021/acs.orglett.2c03356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Quynh H. Nguyen
- Department of Chemistry, Research Institute for Natural Sciences and Center for New Directions in Organic Synthesis (CNOS), Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea
| | - Tae-Woong Um
- Department of Chemistry, Research Institute for Natural Sciences and Center for New Directions in Organic Synthesis (CNOS), Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea
| | - Seunghoon Shin
- Department of Chemistry, Research Institute for Natural Sciences and Center for New Directions in Organic Synthesis (CNOS), Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea
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Abstract
A radical shift toward energy transfer photocatalysis from electron transfer photocatalysis under visible-light photoirradiation is often due to the greener prospects of atom and process economy. Recent advances in energy transfer photocatalysis embrace unique strategies for direct small-molecule activation and sometimes extraordinary chemical bond formation in the absence of additional/sacrificial reagents. Selective energy transfer photocatalysis requires careful selection of substrates and photocatalysts for a perfect match with respect to their triplet energies while having incompatible redox potentials to prevent competitive electron transfer pathways. Substrates containing labile N-O bonds are potential targets for generating reactive key intermediates via photocatalysis to access a variety of functionalized molecules. Typically, the differential electron densities of N and O heteroatoms have been exploited for generation of either N- or O-centered radical intermediates from the functionalized substrates by the electron transfer pathway. However, the latest developments involve direct N-O bond homolysis via energy transfer to generate both N- and O-centered radicals for their subsequent utilization in diverse organic transformations, also in the absence of sacrificial redox reagents. In this Account, we highlight our key contributions in the field of N-O bond activation via energy transfer photocatalysis to generate reactive radical intermediates, with coverage of useful mechanistic insights. More specifically, well-designed N-O bond-containing substrates such as 1,2,4-oxadiazolines, oxime esters, N-indolyl carbonates, and N-enoxybenzotriazoles were successfully utilized in versatile transformations involving selective energy transfer over electron transfer from photocatalysts with high triplet state energy. Direct access to reactive N-, O-, and C-centered (if decarboxylation follows) radical intermediates was achieved for diverse cross-couplings and rearrangement processes. In particular, a variety of open-shell nitrogen reactive intermediates, including N(sp2) and N(sp3) radicals and nitrenes, have been utilized. Notably, diversified transformations of identical substrates have been achieved through careful control of the reaction conditions. 1,2,4-Oxadiazolines were converted into spiro-azolactams through iminyl intermediates in the presence of 1O2, benzimidazoles, or sulfoximines with external sulfoxide reagent through triplet nitrene intermediates under inert conditions. Besides, oxime esters underwent either intramolecular C(sp3)-N radical-radical coupling or intermolecular C(sp3)-N radical-radical coupling by a combined energy transfer-hydrogen atom transfer strategy. Furthermore, a series of electrochemical and photophysical experiments as well as computational studies were performed to substantiate the proposed selective energy-transfer-driven reaction pathways. We hope that this Account will serve as a guide for the rational design of selective energy transfer processes through the activation of further labile chemical bonds.
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Affiliation(s)
- Da Seul Lee
- Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul06974, Republic of Korea
| | - Vineet Kumar Soni
- Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul06974, Republic of Korea
| | - Eun Jin Cho
- Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul06974, Republic of Korea
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