1
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Feng S, Su R. Synthetic Chemistry in Flow: From Photolysis & Homogeneous Photocatalysis to Heterogeneous Photocatalysis. CHEMSUSCHEM 2024:e202400064. [PMID: 38608169 DOI: 10.1002/cssc.202400064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 03/08/2024] [Indexed: 04/14/2024]
Abstract
Photocatalytic synthesis of value-added chemicals has gained increasing attention in recent years owing to its versatility in driving many important reactions under ambient conditions. Selective hydrogenation, oxidation, coupling, and halogenation with a high conversion of the reactants have been realized using designed photocatalysts in batch reactors with small volumes at a laboratory scale; however, scaling-up remains a critical challenge due to inefficient utilization of incident light and active sites of the photocatalysts, resulting in poor catalytic performance that hinders its practical applications. Flow systems are considered one of the solutions for practical applications of light-driven reactions and have experienced great success in photolytic and homogeneous photocatalysis, yet their applications in heterogeneous photocatalysis are still under development. In this perspective, we have summarized recent progress in photolytic and photocatalytic synthetic chemistry performed in flow systems from the view of reactor design with a special focus on heterogeneous photocatalysis. The advantages and limitations of different flow systems, as well as some practical considerations of design strategies are discussed.
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Affiliation(s)
- Sitong Feng
- Soochow Institute for Energy and Materials Innovations (SIEMIS), Soochow University, 215006, Suzhou, China
| | - Ren Su
- Soochow Institute for Energy and Materials Innovations (SIEMIS), Soochow University, 215006, Suzhou, China
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2
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Rani S, Aslam S, Lal K, Noreen S, Alsader KAM, Hussain R, Shirinfar B, Ahmed N. Electrochemical C-H/C-C Bond Oxygenation: A Potential Technology for Plastic Depolymerization. CHEM REC 2024; 24:e202300331. [PMID: 38063812 DOI: 10.1002/tcr.202300331] [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: 10/27/2023] [Revised: 11/23/2023] [Indexed: 03/10/2024]
Abstract
Herein, we provide eco-friendly and safely operated electrocatalytic methods for the selective oxidation directly or with water, air, light, metal catalyst or other mediators serving as the only oxygen supply. Heavy metals, stoichiometric chemical oxidants, or harsh conditions were drawbacks of earlier oxidative cleavage techniques. It has recently come to light that a crucial stage in the deconstruction of plastic waste and the utilization of biomass is the selective activation of inert C(sp3 )-C/H(sp3 ) bonds, which continues to be a significant obstacle in the chemical upcycling of resistant polyolefin waste. An appealing alternative to chemical oxidations using oxygen and catalysts is direct or indirect electrochemical conversion. An essential transition in the chemical and pharmaceutical industries is the electrochemical oxidation of C-H/C-C bonds. In this review, we discuss cutting-edge approaches to chemically recycle commercial plastics and feasible C-C/C-H bonds oxygenation routes for industrial scale-up.
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Affiliation(s)
- Sadia Rani
- Department of Chemistry, The Women University Multan, Multan, 60000, Pakistan
| | - Samina Aslam
- Department of Chemistry, The Women University Multan, Multan, 60000, Pakistan
| | - Kiran Lal
- Department of Chemistry, The Women University Multan, Multan, 60000, Pakistan
| | - Sobia Noreen
- Institute of Chemistry, University of Sargodha, Sargodha, 40100, Pakistan
| | | | - Riaz Hussain
- Department of Chemistry, University of Education Lahore, D.G. Khan Campus, 32200, Pakistan
| | - Bahareh Shirinfar
- West Herts College - University of Hertfordshire, Watford, WD17 3EZ, London, United Kingdom
| | - Nisar Ahmed
- School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, United Kingdom
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3
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Huo T, Zhao X, Cheng Z, Wei J, Zhu M, Dou X, Jiao N. Late-stage modification of bioactive compounds: Improving druggability through efficient molecular editing. Acta Pharm Sin B 2024; 14:1030-1076. [PMID: 38487004 PMCID: PMC10935128 DOI: 10.1016/j.apsb.2023.11.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 10/14/2023] [Accepted: 11/13/2023] [Indexed: 03/17/2024] Open
Abstract
Synthetic chemistry plays an indispensable role in drug discovery, contributing to hit compounds identification, lead compounds optimization, candidate drugs preparation, and so on. As Nobel Prize laureate James Black emphasized, "the most fruitful basis for the discovery of a new drug is to start with an old drug"1. Late-stage modification or functionalization of drugs, natural products and bioactive compounds have garnered significant interest due to its ability to introduce diverse elements into bioactive compounds promptly. Such modifications alter the chemical space and physiochemical properties of these compounds, ultimately influencing their potency and druggability. To enrich a toolbox of chemical modification methods for drug discovery, this review focuses on the incorporation of halogen, oxygen, and nitrogen-the ubiquitous elements in pharmacophore components of the marketed drugs-through late-stage modification in recent two decades, and discusses the state and challenges faced in these fields. We also emphasize that increasing cooperation between chemists and pharmacists may be conducive to the rapid discovery of new activities of the functionalized molecules. Ultimately, we hope this review would serve as a valuable resource, facilitating the application of late-stage modification in the construction of novel molecules and inspiring innovative concepts for designing and building new drugs.
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Affiliation(s)
- Tongyu Huo
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Xinyi Zhao
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Zengrui Cheng
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Jialiang Wei
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
- Changping Laboratory, Beijing 102206, China
| | - Minghui Zhu
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Xiaodong Dou
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Ning Jiao
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
- Changping Laboratory, Beijing 102206, China
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, East China Normal University, Shanghai 200062, China
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4
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Wei L, Bai W, Hu Z, Yang Z, Xu L. Visible light-induced metal-free chemoselective oxidative cleavage of benzyl C-heteroatom (N, S, Se) bonds utilizing organoboron photocatalysts. Chem Commun (Camb) 2023; 59:13344-13347. [PMID: 37872818 DOI: 10.1039/d3cc04073a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
The oxidation process is widely explored and used to synthesize diverse organic chemicals. Herein, a unified metal-free photooxidative platform for the cleavage of C-heteroatom bonds has been developed. In these reactions, the aminoquinolate diarylboron (AQDAB) complex is utilized as the photocatalyst, instigating the oxidation process induced by visible light. The cleavage of C-heteroatom bonds can be achieved chemoselectively, affording the formal carbonylation product of C-N, C-S, and C-Se bonds. This method provides a channel for connecting amines, thiols, or selenides with the carbonyl compounds directly, broadening the potential applications of oxidation as a synthetic tool.
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Affiliation(s)
- Lanfeng Wei
- School of Safety Science and Engineering, Xinjiang Institute of Engineering, Urumqi, Xinjiang 830000, China.
- Key Laboratory of Coal Resources and Green Mining in Xinjiang, Ministry of Education, Urumqi, Xinjiang 830000, China
| | - Wenbo Bai
- School of Chemistry and Chemical Engineering/State Key Laboratory Incubation Base for Green Processing of Chemical Engineering, Shihezi University, Shihezi, 832003, China.
| | - Zhiyan Hu
- School of Chemistry and Chemical Engineering/State Key Laboratory Incubation Base for Green Processing of Chemical Engineering, Shihezi University, Shihezi, 832003, China.
| | - Zhiyong Yang
- School of Safety Science and Engineering, Xinjiang Institute of Engineering, Urumqi, Xinjiang 830000, China.
- Key Laboratory of Coal Resources and Green Mining in Xinjiang, Ministry of Education, Urumqi, Xinjiang 830000, China
| | - Liang Xu
- School of Chemistry and Chemical Engineering/State Key Laboratory Incubation Base for Green Processing of Chemical Engineering, Shihezi University, Shihezi, 832003, China.
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5
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Ghosh SK, He L, Tang Z, Comito RJ. Selective and Functional-Group-Tolerant Photoalkylation of Imines by Energy-Transfer Photocatalysis. J Org Chem 2023; 88:15209-15217. [PMID: 37875007 DOI: 10.1021/acs.joc.3c01722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2023]
Abstract
Basic amines show broad bioactivity and remain a promising source of new medicines. The direct photoalkylation of imines offers a promising strategy for complex amines. However, the lack of efficient imine photoreactivity hinders this reaction and remains a fundamental limitation in organic photochemistry. We report an efficient photoalkylation of imines that provides primary amines directly without protecting or leaving groups. The transformation effects C-H addition across N-H imines under energy-transfer photocatalysis by a ketone. Our method is distinguished from organometallic, metal-catalyzed, and photoredox approaches to imine alkylation by its lack of protecting groups and its broad scope, which includes unactivated alkanes, protic substrates, basic amines, heterocycles, and ketone imines. We highlight this scope through the condensation and alkylation of two pharmaceutical ketones, providing complex amines succinctly. Our mechanistic analysis supports a three-step process, involving hydrogen-atom transfer to an imine triplet excited state, intersystem crossing, and radical recombination, with photocatalytic enhancement through energy transfer. We further show that N-H imines are more photoreactive than N-substituted imines, a distinction partially explained by sterics and side reactions. To fully explain this distinction, we introduce the thermodynamic parameter excited-state hydrogen-atom affinity, which is highly effective at predicting the photoreactivity of imines.
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Affiliation(s)
- Subrata K Ghosh
- The University of Houston, 4800 Calhoun Road, Houston, Texas 77004, United States
| | - Lizhe He
- The University of Houston, 4800 Calhoun Road, Houston, Texas 77004, United States
| | - Zilu Tang
- The University of Houston, 4800 Calhoun Road, Houston, Texas 77004, United States
| | - Robert J Comito
- The University of Houston, 4800 Calhoun Road, Houston, Texas 77004, United States
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6
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Žurauskas J, Boháčová S, Wu S, Butera V, Schmid S, Domański M, Slanina T, Barham JP. Electron-Poor Acridones and Acridiniums as Super Photooxidants in Molecular Photoelectrochemistry by Unusual Mechanisms. Angew Chem Int Ed Engl 2023; 62:e202307550. [PMID: 37584300 DOI: 10.1002/anie.202307550] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 08/14/2023] [Accepted: 08/15/2023] [Indexed: 08/17/2023]
Abstract
Electron-deficient acridones and in situ generated acridinium salts are reported as potent, closed-shell photooxidants that undergo surprising mechanisms. When bridging acyclic triarylamine catalysts with a carbonyl group (acridones), this completely diverts their behavior away from open-shell, radical cationic, 'beyond diffusion' photocatalysis to closed-shell, neutral, diffusion-controlled photocatalysis. Brønsted acid activation of acridones dramatically increases excited state oxidation power (by +0.8 V). Upon reduction of protonated acridones, they transform to electron-deficient acridinium salts as even more potent photooxidants (*E1/2 =+2.56-3.05 V vs SCE). These oxidize even electron-deficient arenes where conventional acridinium salt photooxidants have thusfar been limited to electron-rich arenes. Surprisingly, upon photoexcitation these electron-deficient acridinium salts appear to undergo two electron reductive quenching to form acridinide anions, spectroscopically-detected as their protonated forms. This new behaviour is partly enabled by a catalyst preassembly with the arene, and contrasts to conventional SET reductive quenching of acridinium salts. Critically, this study illustrates how redox active chromophoric molecules initially considered photocatalysts can transform during the reaction to catalytically active species with completely different redox and spectroscopic properties.
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Affiliation(s)
- Jonas Žurauskas
- Institute of Organic Chemistry, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Soňa Boháčová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 16000, Prague 6, Czech Republic
| | - Shangze Wu
- Institute of Organic Chemistry, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Valeria Butera
- Central European Institute of Technology, CEITEC, 61200 Brno (Czech Republic), Department of Science and Biological Chemical and Pharmaceutical Technologies, University of Palermo, 90128, Palermo, Italy
| | - Simon Schmid
- Institute of Organic Chemistry, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Michał Domański
- Institute of Organic Chemistry, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Tomáš Slanina
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 16000, Prague 6, Czech Republic
| | - Joshua P Barham
- Institute of Organic Chemistry, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
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7
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Lepori M, Schmid S, Barham JP. Photoredox catalysis harvesting multiple photon or electrochemical energies. Beilstein J Org Chem 2023; 19:1055-1145. [PMID: 37533877 PMCID: PMC10390843 DOI: 10.3762/bjoc.19.81] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 07/07/2023] [Indexed: 08/04/2023] Open
Abstract
Photoredox catalysis (PRC) is a cutting-edge frontier for single electron-transfer (SET) reactions, enabling the generation of reactive intermediates for both oxidative and reductive processes via photon activation of a catalyst. Although this represents a significant step towards chemoselective and, more generally, sustainable chemistry, its efficacy is limited by the energy of visible light photons. Nowadays, excellent alternative conditions are available to overcome these limitations, harvesting two different but correlated concepts: the use of multi-photon processes such as consecutive photoinduced electron transfer (conPET) and the combination of photo- and electrochemistry in synthetic photoelectrochemistry (PEC). Herein, we review the most recent contributions to these fields in both oxidative and reductive activations of organic functional groups. New opportunities for organic chemists are captured, such as selective reactions employing super-oxidants and super-reductants to engage unactivated chemical feedstocks, and scalability up to gram scales in continuous flow. This review provides comparisons between the two techniques (multi-photon photoredox catalysis and PEC) to help the reader to fully understand their similarities, differences and potential applications and to therefore choose which method is the most appropriate for a given reaction, scale and purpose of a project.
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Affiliation(s)
- Mattia Lepori
- Fakultät für Chemie und Pharmazie, Universität Regensburg, Universitatsstraße 31, 93040 Regensburg, Germany
| | - Simon Schmid
- Fakultät für Chemie und Pharmazie, Universität Regensburg, Universitatsstraße 31, 93040 Regensburg, Germany
| | - Joshua P Barham
- Fakultät für Chemie und Pharmazie, Universität Regensburg, Universitatsstraße 31, 93040 Regensburg, Germany
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8
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Horsewill S, Hierlmeier G, Farasat Z, Barham JP, Scott DJ. Shining Fresh Light on Complex Photoredox Mechanisms through Isolation of Intermediate Radical Anions. ACS Catal 2023; 13:9392-9403. [PMID: 37497378 PMCID: PMC10367049 DOI: 10.1021/acscatal.3c02515] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 06/20/2023] [Indexed: 07/28/2023]
Abstract
Photoredox catalysis (PRC) has gained enormous and wide-ranging interest in recent years but has also been subject to significant mechanistic uncertainty, even controversy. To provide a method by which the missing understanding can begin to be filled in, we demonstrate herein that it is possible to isolate as authentic materials the one-electron reduction products of representative PRC catalysts (PCs). Specifically, KC8 reduction of both 9,10-dicyanoanthracene and a naphthalene monoamide derivative in the presence of a cryptand provides convenient access to the corresponding [K(crypt)+][PC·-] salts as clean materials that can be fully characterized by techniques including EPR and XRD. Because PC·- states are key intermediates in PRC reactions, such isolation allows for highly controlled study of these anions' specific reactivity and hence their mechanistic roles. As a demonstration of this principle, we show that these salts can be used to conveniently interrogate the mechanisms of recent, high-profile "conPET" and "e-PRC" reactions, which are currently the subject of both significant interest and acute controversy. Using very simple experiments, we are able to provide striking insights into these reactions' underlying mechanisms and to observe surprising levels of hidden complexity that would otherwise have been very challenging to identify and that emphasize the care and control that are needed when interrogating and interpreting PRC mechanisms. These studies provide a foundation for the study of a far broader range of questions around conPET, e-PRC, and other PRC reaction mechanisms in the future, using the same strategy of PC·- isolation.
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Affiliation(s)
- Samuel
J. Horsewill
- Department
of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Gabriele Hierlmeier
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Zahra Farasat
- Professor
Rashidi Laboratory of Organometallic Chemistry, Department of Chemistry,
College of Sciences, Shiraz University, Shiraz, Fars 71467-13565, Iran
| | - Joshua P. Barham
- Institute
of Organic Chemistry, University of Regensburg, Universitätsstr. 31, Regensburg, Bayern 93053, Germany
| | - Daniel J. Scott
- Department
of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
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9
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Luo MJ, Zhou W, Yang R, Ding H, Song XR, Xiao Q. Electrochemically enabled decyanative C(sp 3)-H oxygenation of N-cyanomethylamines to formamides. Org Biomol Chem 2023; 21:2917-2921. [PMID: 36942930 DOI: 10.1039/d3ob00313b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
Selective oxygenation of C(sp3)-H bonds adjacent to nitrogen atoms is a highly attractive strategy for synthesizing various formamide derivatives while preserving the substrate skeletons. Herein, an environmentally benign electrochemically enabled decyanative C(sp3)-H oxygenation of N-cyanomethylamines using H2O as a carbonyl oxygen atom source is described, leading to the synthesis of a large class of formamides in good to excellent yields with a broad substrate scope under metal- and oxidant-free conditions. This electrochemical technology highlights the facile incorporation of N-formyl into some important bioactive molecules.
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Affiliation(s)
- Mu-Jia Luo
- Key Laboratory of Organic Chemistry of Jiangxi Province, Jiangxi Science & Technology Normal University, Nanchang, 330013, China.
| | - Wei Zhou
- Key Laboratory of Organic Chemistry of Jiangxi Province, Jiangxi Science & Technology Normal University, Nanchang, 330013, China.
| | - Ruchun Yang
- Key Laboratory of Organic Chemistry of Jiangxi Province, Jiangxi Science & Technology Normal University, Nanchang, 330013, China.
| | - Haixin Ding
- Key Laboratory of Organic Chemistry of Jiangxi Province, Jiangxi Science & Technology Normal University, Nanchang, 330013, China.
| | - Xian-Rong Song
- Key Laboratory of Organic Chemistry of Jiangxi Province, Jiangxi Science & Technology Normal University, Nanchang, 330013, China.
| | - Qiang Xiao
- Key Laboratory of Organic Chemistry of Jiangxi Province, Jiangxi Science & Technology Normal University, Nanchang, 330013, China.
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10
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Zeng FL, Zhu HL, Wang RN, Yuan XY, Sun K, Qu LB, Chen XL, Yu B. Bismuth vanadate: A versatile heterogeneous catalyst for photocatalytic functionalization of C(sp2)–H bonds. CHINESE JOURNAL OF CATALYSIS 2023. [DOI: 10.1016/s1872-2067(23)64391-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
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11
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Franceschi P, Cuadros S, Goti G, Dell'Amico L. Mechanisms and Synthetic Strategies in Visible Light-Driven [2+2]-Heterocycloadditions. Angew Chem Int Ed Engl 2023; 62:e202217210. [PMID: 36576751 DOI: 10.1002/anie.202217210] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 12/27/2022] [Accepted: 12/28/2022] [Indexed: 12/29/2022]
Abstract
The synthesis of four membered heterocycles usually requires multi-step procedures and prefunctionalized reactants. A straightforward alternative is the photochemical [2+2]-heterocycloaddition between an alkene and a carbonyl derivative, conventionally based on the photoexcitation of this latter. However, this approach is limited by the absorption profile of the carbonyl, requiring in most of the cases the use of high-energy UV-light, that often results in undesired side reactions and/or the degradation of the reaction components. The development of new and milder visible light-driven [2+2]-heterocycloadditions is, therefore, highly desirable. In this Review, we highlight the most relevant achievements in the development of [2+2]-heterocycloadditions promoted by visible light, with a particular emphasis on the involved reaction mechanisms. The open challenges will also be discussed, suggesting new possible evolutions, and stimulating new methodological developments in the field.
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Affiliation(s)
- Pietro Franceschi
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Sara Cuadros
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Giulio Goti
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Luca Dell'Amico
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
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12
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Lin X, Li N, Zhu C, Sun B. An Efficient Synthesis of Rivaroxaban. ChemistrySelect 2023. [DOI: 10.1002/slct.202204644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Xiaoyu Lin
- School of Pharmaceutical Sciences Nanjing Tech University 30 South Puzhu Road Nanjing 210000 China
| | - Nanlian Li
- School of Pharmaceutical Sciences Nanjing Tech University 30 South Puzhu Road Nanjing 210000 China
| | - Chenlong Zhu
- School of Pharmaceutical Sciences Nanjing Tech University 30 South Puzhu Road Nanjing 210000 China
| | - Bingfeng Sun
- School of Pharmaceutical Sciences Nanjing Tech University 30 South Puzhu Road Nanjing 210000 China
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13
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Abstract
The emergence of modern photocatalysis, characterized by mildness and selectivity, has significantly spurred innovative late-stage C-H functionalization approaches that make use of low energy photons as a controllable energy source. Compared to traditional late-stage functionalization strategies, photocatalysis paves the way toward complementary and/or previously unattainable regio- and chemoselectivities. Merging the compelling benefits of photocatalysis with the late-stage functionalization workflow offers a potentially unmatched arsenal to tackle drug development campaigns and beyond. This Review highlights the photocatalytic late-stage C-H functionalization strategies of small-molecule drugs, agrochemicals, and natural products, classified according to the targeted C-H bond and the newly formed one. Emphasis is devoted to identifying, describing, and comparing the main mechanistic scenarios. The Review draws a critical comparison between established ionic chemistry and photocatalyzed radical-based manifolds. The Review aims to establish the current state-of-the-art and illustrate the key unsolved challenges to be addressed in the future. The authors aim to introduce the general readership to the main approaches toward photocatalytic late-stage C-H functionalization, and specialist practitioners to the critical evaluation of the current methodologies, potential for improvement, and future uncharted directions.
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Affiliation(s)
- Peter Bellotti
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 36, 48149Münster, Germany
| | - Huan-Ming Huang
- School of Physical Science and Technology, ShanghaiTech University, 201210Shanghai, China
| | - Teresa Faber
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 36, 48149Münster, Germany
| | - Frank Glorius
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 36, 48149Münster, Germany
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14
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Caby S, Marín Oliva L, Bardagi JI. Unravelling the Effect of Water Addition in Consecutive Photocatalysis with Naphthalene Diimide. J Org Chem 2023; 88:711-716. [PMID: 36542788 DOI: 10.1021/acs.joc.2c02172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We describe the effect of water addition in the catalyst performance for a C-H functionalization of benzene. Improved yields and selectivity were achieved in a consecutive photoredox catalysis in contrast to the reaction without water. Mechanistic analysis demonstrated this is due to a better catalyst stability and faster kinetic rather than a change in the different steps of the mechanism. The addition of water constitutes a convenient approach to improve catalyst performance, and it was also observed with other catalysts.
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Affiliation(s)
- Sofia Caby
- INFIQC, Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba, Argentina
| | - Laureano Marín Oliva
- INFIQC, Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba, Argentina
| | - Javier I Bardagi
- INFIQC, Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba, Argentina
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15
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Glaser F, Wenger OS. Sensitizer-controlled photochemical reactivity via upconversion of red light. Chem Sci 2022; 14:149-161. [PMID: 36605743 PMCID: PMC9769107 DOI: 10.1039/d2sc05229f] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 11/21/2022] [Indexed: 12/02/2022] Open
Abstract
By combining the energy input from two red photons, chemical reactions that would normally require blue or ultraviolet irradiation become accessible. Key advantages of this biphotonic excitation strategy are that red light usually penetrates deeper into complex reaction mixtures and causes less photo-damage than direct illumination in the blue or ultraviolet. Here, we demonstrate that the primary light-absorber of a dual photocatalytic system comprised of a transition metal-based photosensitizer and an organic co-catalyst can completely alter the reaction outcome. Photochemical reductions are achieved with a copper(i) complex in the presence of a sacrificial electron donor, whereas oxidative substrate activation occurs with an osmium(ii) photosensitizer. Based on time-resolved laser spectroscopy, this changeover in photochemical reactivity is due to different underlying biphotonic mechanisms. Following triplet energy transfer from the osmium(ii) photosensitizer to 9,10-dicyanoanthracene (DCA) and subsequent triplet-triplet annihilation upconversion, the fluorescent singlet excited state of DCA triggers oxidative substrate activation, which initiates the cis to trans isomerization of an olefin, a [2 + 2] cycloaddition, an aryl ether to ester rearrangement, and a Newman-Kwart rearrangement. This oxidative substrate activation stands in contrast to the reactivity with a copper(i) photosensitizer, where photoinduced electron transfer generates the DCA radical anion, which upon further excitation triggers reductive dehalogenations and detosylations. Our study provides the proof-of-concept for controlling the outcome of a red-light driven biphotonic reaction by altering the photosensitizer, and this seems relevant in the greater context of tailoring photochemical reactivities.
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Affiliation(s)
- Felix Glaser
- Department of Chemistry, University of BaselSt. Johanns-Ring 194056 BaselSwitzerland
| | - Oliver S. Wenger
- Department of Chemistry, University of BaselSt. Johanns-Ring 194056 BaselSwitzerland
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Yakubov S, Stockerl WJ, Tian X, Shahin A, Mandigma MJP, Gschwind RM, Barham JP. Benzoates as photosensitization catalysts and auxiliaries in efficient, practical, light-powered direct C(sp 3)-H fluorinations. Chem Sci 2022; 13:14041-14051. [PMID: 36540818 PMCID: PMC9728569 DOI: 10.1039/d2sc05735b] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Accepted: 10/28/2022] [Indexed: 12/14/2023] Open
Abstract
Of the methods for direct fluorination of unactivated C(sp3)-H bonds, photosensitization of SelectFluor is a promising approach. Although many substrates can be activated with photosensitizing catalysts, issues remain that hamper fluorination of complex molecules. Alcohol- or amine-containing functional groups are not tolerated, fluorination regioselectivity follows factors endogenous to the substrate and cannot be influenced by the catalyst, and reactions are highly air-sensitive. We report that benzoyl groups serve as highly efficient photosensitizers which, in combination with SelectFluor, enable visible light-powered direct fluorination of unactivated C(sp3)-H bonds. Compared to previous photosensitizer architectures, the benzoyls have versatility to function both (i) as a photosensitizing catalyst for simple substrate fluorinations and (ii) as photosensitizing auxiliaries for complex molecule fluorinations that are easily installed and removed without compromising yield. Our auxiliary approach (i) substantially decreases the reaction's induction period, (ii) enables C(sp3)-H fluorination of many substrates that fail under catalytic conditions, (iii) increases kinetic reproducibility, and (iv) promotes reactions to higher yields, in shorter times, on multigram scales, and even under air. Observations and mechanistic studies suggest an intimate 'assembly' of auxiliary and SelectFluor prior/after photoexcitation. The auxiliary allows other EnT photochemistry under air. Examples show how auxiliary placement proximally directs regioselectivity, where previous methods are substrate-directed.
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Affiliation(s)
- Shahboz Yakubov
- Fakultät für Chemie und Pharmazie, Universität Regensburg 93040 Regensburg Germany
| | - Willibald J Stockerl
- Fakultät für Chemie und Pharmazie, Universität Regensburg 93040 Regensburg Germany
| | - Xianhai Tian
- Fakultät für Chemie und Pharmazie, Universität Regensburg 93040 Regensburg Germany
| | - Ahmed Shahin
- Fakultät für Chemie und Pharmazie, Universität Regensburg 93040 Regensburg Germany
- Chemistry Department, Faculty of Science, Benha University 13518 Benha Egypt
| | - Mark John P Mandigma
- Fakultät für Chemie und Pharmazie, Universität Regensburg 93040 Regensburg Germany
| | - Ruth M Gschwind
- Fakultät für Chemie und Pharmazie, Universität Regensburg 93040 Regensburg Germany
| | - Joshua P Barham
- Fakultät für Chemie und Pharmazie, Universität Regensburg 93040 Regensburg Germany
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17
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Photoelectrochemical asymmetric catalysis enables site- and enantioselective cyanation of benzylic C–H bonds. Nat Catal 2022. [DOI: 10.1038/s41929-022-00855-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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18
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Oxidative lactonization of C(sp3)-H bond in methyl aromatic alcohols enabled by proton-coupled electron transfer. Sci China Chem 2022. [DOI: 10.1007/s11426-022-1283-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Domański M, Žurauskas J, Barham JP. Tunable Microwave Flow System for Scalable Synthesis of Alkyl Imidazolium-type Ionic Liquids. Org Process Res Dev 2022. [DOI: 10.1021/acs.oprd.2c00180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Michał Domański
- Institute of Organic Chemistry, University of Regensburg, Universitätsstr. 31, Regensburg 93040, Germany
| | - Jonas Žurauskas
- Institute of Organic Chemistry, University of Regensburg, Universitätsstr. 31, Regensburg 93040, Germany
| | - Joshua P. Barham
- Institute of Organic Chemistry, University of Regensburg, Universitätsstr. 31, Regensburg 93040, Germany
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20
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Glaser F, Wenger OS. Red Light-Based Dual Photoredox Strategy Resembling the Z-Scheme of Natural Photosynthesis. JACS AU 2022; 2:1488-1503. [PMID: 35783177 PMCID: PMC9241018 DOI: 10.1021/jacsau.2c00265] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 05/30/2022] [Accepted: 05/31/2022] [Indexed: 05/11/2023]
Abstract
Photoredox catalysis typically relies on the use of single chromophores, whereas strategies, in which two different light absorbers are combined, are rare. In photosystems I and II of green plants, the two separate chromophores P680 and P700 both absorb light independently of one another, and then their excitation energy is combined in the so-called Z-scheme, to drive an overall reaction that is thermodynamically very demanding. Here, we adapt this concept to perform photoredox reactions on organic substrates with the combined energy input of two red photons instead of blue or UV light. Specifically, a CuI bis(α-diimine) complex in combination with in situ formed 9,10-dicyanoanthracenyl radical anion in the presence of excess diisopropylethylamine catalyzes ca. 50 dehalogenation and detosylation reactions. This dual photoredox approach seems useful because red light is less damaging and has a greater penetration depth than blue or UV radiation. UV-vis transient absorption spectroscopy reveals that the subtle change in solvent from acetonitrile to acetone induces a changeover in the reaction mechanism, involving either a dominant photoinduced electron transfer or a dominant triplet-triplet energy transfer pathway. Our study illustrates the mechanistic complexity in systems operating under multiphotonic excitation conditions, and it provides insights into how the competition between desirable and unwanted reaction steps can become more controllable.
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Zhang Q, Hou J, Huang Y, Zhan LW, Li BD. Visible light-promoted synthesis of ureas and formamides from amines and CO 2. Chem Commun (Camb) 2022; 58:4599-4602. [PMID: 35311867 DOI: 10.1039/d2cc00572g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A divergent visible-light-induced Ph3P-promoted method for the synthesis of ureas and formamides from amines and CO2 is reported. Without external additions, a range of ureas could be directly accessed under ambient temperature and pressure. Using triisopropylsilanethiol as the hydrogen source, formamides could be produced.
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Affiliation(s)
- Qian Zhang
- College of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Jing Hou
- College of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Yan Huang
- College of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Le-Wu Zhan
- College of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Bin-Dong Li
- College of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
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Barham JP, Kaur J. Site-Selective C(sp3)–H Functionalizations Mediated by Hydrogen Atom Transfer Reactions via α-Amino/α-Amido Radicals. SYNTHESIS-STUTTGART 2022. [DOI: 10.1055/a-1677-6619] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
AbstractAmines and amides, as N-containing compounds, are ubiquitous in pharmaceutically-active scaffolds, natural products, agrochemicals, and peptides. Amides in nature bear a key responsibility for imparting three-dimensional structure, such as in proteins. Structural modifications to amines and amides, especially at their positions α to N, bring about profound changes in biological activity oftentimes leading to more desirable pharmacological profiles of small drug molecules. A number of recent developments in synthetic methodology for the functionalizations of amines and amides omit the need of their directing groups or pre-functionalizations, achieving direct activation of the otherwise relatively benign C(sp3)–H bonds α to N. Among these, hydrogen atom transfer (HAT) has proven a very powerful platform for the selective activation of amines and amides to their α-amino and α-amido radicals, which can then be employed to furnish C–C and C–X (X = heteroatom) bonds. The abilities to both form these radicals and control their reactivity in a site-selective manner is of utmost importance for such chemistries to witness applications in late-stage functionalization. Therefore, this review captures contemporary HAT strategies to realize chemo- and regioselective amine and amide α-C(sp3)–H functionalization, based on bond strengths, bond polarities, reversible HAT equilibria, traceless electrostatic-directing auxiliaries, and steric effects of in situ-generated HAT agents.1 Introduction2 Functionalizations of Amines3 Functionalizations of Carbamates4 Functionalizations of Amides5 Conclusion
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