1
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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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2
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Williams OP, Chmiel AF, Mikhael M, Bates DM, Yeung CS, Wickens ZK. Practical and General Alcohol Deoxygenation Protocol. Angew Chem Int Ed Engl 2023; 62:e202300178. [PMID: 36840940 PMCID: PMC10121858 DOI: 10.1002/anie.202300178] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 02/23/2023] [Accepted: 02/23/2023] [Indexed: 02/26/2023]
Abstract
Herein, we describe a practical protocol for the removal of alcohol functional groups through reductive cleavage of their benzoate ester analogs. This transformation requires a strong single electron transfer (SET) reductant and a means to accelerate slow fragmentation following substrate reduction. To accomplish this, we developed a photocatalytic system that generates a potent reductant from formate salts alongside Brønsted or Lewis acids that promote fragmentation of the reduced intermediate. This deoxygenation procedure is effective across structurally and electronically diverse alcohols and enables a variety of difficult net transformations. This protocol requires no precautions to exclude air or moisture and remains efficient on multigram scale. Finally, the system can be adapted to a one-pot benzoylation-deoxygenation sequence to enable direct alcohol deletion. Mechanistic studies validate that the role of acidic additives is to promote the key C(sp3 )-O bond fragmentation step.
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Affiliation(s)
- Oliver P. Williams
- Department of Chemistry, University of Wisconsin-Madison; Madison, Wisconsin, 53706, United States
| | - Alyah F. Chmiel
- Department of Chemistry, University of Wisconsin-Madison; Madison, Wisconsin, 53706, United States
| | - Myriam Mikhael
- Discovery Chemistry, Merck & Co., Inc., 33 Avenue Louis Pasteur, Boston, MA 02115, United States
| | - Desiree M. Bates
- Department of Chemistry, University of Wisconsin-Madison; Madison, Wisconsin, 53706, United States
| | - Charles S. Yeung
- Discovery Chemistry, Merck & Co., Inc., 33 Avenue Louis Pasteur, Boston, MA 02115, United States
| | - Zachary K. Wickens
- Department of Chemistry, University of Wisconsin-Madison; Madison, Wisconsin, 53706, United States
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3
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Villo P, Shatskiy A, Kärkäs MD, Lundberg H. Electrosynthetic C-O Bond Activation in Alcohols and Alcohol Derivatives. Angew Chem Int Ed Engl 2023; 62:e202211952. [PMID: 36278406 PMCID: PMC10107720 DOI: 10.1002/anie.202211952] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Indexed: 11/07/2022]
Abstract
Alcohols and their derivatives are ubiquitous and versatile motifs in organic synthesis. Deoxygenative transformations of these compounds are often challenging due to the thermodynamic penalty associated with the cleavage of the C-O bond. However, electrochemically driven redox events have been shown to facilitate the C-O bond cleavage in alcohols and their derivatives either through direct electron transfer or through the use of electron transfer mediators and electroactive catalysts. Herein, a comprehensive overview of preparative electrochemically mediated protocols for C-O bond activation and functionalization is detailed, including direct and indirect electrosynthetic methods, as well as photoelectrochemical strategies.
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Affiliation(s)
- Piret Villo
- Department of Chemistry, KTH Royal Institute of Technology, SE-100 44, Stockholm, Sweden
| | - Andrey Shatskiy
- Department of Chemistry, KTH Royal Institute of Technology, SE-100 44, Stockholm, Sweden
| | - Markus D Kärkäs
- Department of Chemistry, KTH Royal Institute of Technology, SE-100 44, Stockholm, Sweden
| | - Helena Lundberg
- Department of Chemistry, KTH Royal Institute of Technology, SE-100 44, Stockholm, Sweden
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4
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Yang K, Wang Y, Luo S, Fu N. Electrophotochemical Metal-Catalyzed Enantioselective Decarboxylative Cyanation. Chemistry 2023; 29:e202203962. [PMID: 36638008 DOI: 10.1002/chem.202203962] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/13/2023] [Accepted: 01/13/2023] [Indexed: 01/14/2023]
Abstract
In contrast to the rapid growth of electrophotocatalysis in recent years, enantioselective catalytic reactions powered by this unique methodology remain rare. In this work, we report an electrophotochemical metal-catalyzed protocol for direct asymmetric decarboxylative cyanation of aliphatic carboxylic acids. The synergistic merging of electrophotochemical cerium catalysis and asymmetric electrochemical copper catalysis permits mild reaction conditions for the formation and utilization of the key carbon centered radicals by combining the power of light and electrical energy. Electrophotochemical cerium catalysis enables radical decarboxylation to produce alkyl radicals, which could be effectively intercepted by asymmetric electrochemical copper catalysis for the construction of C-CN bonds in a highly stereoselective fashion. This environmentally benign method smoothly converts a diverse array of arylacetic acids into the corresponding alkyl nitriles in good yields and enantioselectivities without using chemical oxidants or pre-functionalization of the acid substrates and can be readily scaled up.
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Affiliation(s)
- Kai Yang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, 100190, Beijing, P. R. China
- Center of Basic Molecular Science, Department of Chemistry, Tsinghua University, 100084, Beijing, P. R. China
| | - Yukang Wang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, 100190, Beijing, P. R. China
- University of Chinese Academy of Sciences, 100049, Beijing, P. R. China
| | - Sanzhong Luo
- Center of Basic Molecular Science, Department of Chemistry, Tsinghua University, 100084, Beijing, P. R. China
| | - Niankai Fu
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, 100190, Beijing, P. R. China
- University of Chinese Academy of Sciences, 100049, Beijing, P. R. China
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5
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Tian X, Kaur J, Yakubov S, Barham JP. α-Amino Radical Halogen Atom Transfer Agents for Metallaphotoredox-Catalyzed Cross-Electrophile Couplings of Distinct Organic Halides. CHEMSUSCHEM 2022; 15:e202200906. [PMID: 35587725 PMCID: PMC9541218 DOI: 10.1002/cssc.202200906] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Indexed: 06/15/2023]
Abstract
α-Amino radicals from simple tertiary amines were employed as halogen atom transfer (XAT) agents in metallaphotoredox catalysis for cross-electrophile couplings of organic bromides with organic iodides. This XAT strategy proved to be efficient for the generation of carbon radicals from a range of partners (alkyl, aryl, alkenyl, and alkynyl iodides). The reactivities of these radical intermediates were captured by nickel catalysis with organobromides including aryl, heteroaryl, alkenyl, and alkyl bromides, enabling six diverse C-C bond formations. Classic named reactions including Negishi, Suzuki, Heck, and Sonogashira reactions were readily achieved in a net-reductive fashion under mild conditions. More importantly, the cross coupling was viable with either organic bromide or iodide as limiting reactant based on the availability of substrates, which is beneficial to the late-stage functionalization of complex molecules. The scalability of this method in batch and flow was investigated, further demonstrating its applicability.
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Affiliation(s)
- Xianhai Tian
- Institute of Organic ChemistryUniversity of RegensburgUniversitätsstr. 3193053RegensburgGermany
| | - Jaspreet Kaur
- Institute of Organic ChemistryUniversity of RegensburgUniversitätsstr. 3193053RegensburgGermany
| | - Shahboz Yakubov
- Institute of Organic ChemistryUniversity of RegensburgUniversitätsstr. 3193053RegensburgGermany
| | - Joshua P. Barham
- Institute of Organic ChemistryUniversity of RegensburgUniversitätsstr. 3193053RegensburgGermany
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6
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Peng TY, Xu ZY, Zhang FL, Li B, Xu WP, Fu Y, Wang YF. Dehydroxylative Alkylation of α-Hydroxy Carboxylic Acid Derivatives via a Spin-Center Shift. Angew Chem Int Ed Engl 2022; 61:e202201329. [PMID: 35388555 DOI: 10.1002/anie.202201329] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Indexed: 11/05/2022]
Abstract
A strategically distinct dehydroxylative alkylation reaction of α-hydroxy carboxylic acid derivatives with alkenes is developed. The reaction starts with the attack of a 4-dimethylaminopyridine (DMAP)-boryl radical to the carbonyl oxygen atom, followed by a spin-center shift (SCS) to trigger the C-O bond scission. The resulting α-carbonyl radicals couple with a wide range of alkenes to furnish various alkylated products. This strategy allows for the efficient conversion of a wide array of α-hydroxy amides and esters derived from several biomass molecules and natural products to value-added compounds. Experimental and computational studies verified the reaction mechanism.
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Affiliation(s)
- Tian-Yu Peng
- CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Zhe-Yuan Xu
- CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Feng-Lian Zhang
- CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Bin Li
- CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Wen-Ping Xu
- CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Yao Fu
- CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China
| | - Yi-Feng Wang
- CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China.,State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin, 300071, China
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7
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Sadowski B, Yuan B, Lin Z, Ackermann L. Rhodaelectro-Catalyzed peri-Selective Direct Alkenylations with Weak O-Coordination Enabled by the Hydrogen Evolution Reaction (HER). Angew Chem Int Ed Engl 2022; 61:e202117188. [PMID: 35179817 PMCID: PMC9311442 DOI: 10.1002/anie.202117188] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Indexed: 12/12/2022]
Abstract
Direct C−H functionalizations by electrocatalysis is dominated by strongly coordinating N(sp2)‐directing groups. In sharp contrast, direct electrocatalytic transformations of weakly‐coordinating phenols remain underdeveloped. Herein, electrooxidative peri C−H alkenylations of challenging 1‐naphthols were achieved by versatile rhodium(III) catalysis via user‐friendly constant current electrolysis. The rhodaelectrocatalysis employed readily‐available alkenes and a protic reaction medium and features ample scope, good functional group tolerance and high site‐ and stereoselectivity. The strategy was successfully applied to high‐value, nitrogen‐containing heterocycles, thereby providing direct access to uncommon heterocyclic motifs based on the dihydropyranoquinoline skeleton.
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Affiliation(s)
- Bartłomiej Sadowski
- Institut für Organische und Biomolekulare Chemie and Woehler Research Institute for Sustainable Chemistry (WISCh), Georg-August-Universität Göttingen, Tammannstraße 2, 37077, Göttingen, Germany
| | - Binbin Yuan
- Institut für Organische und Biomolekulare Chemie and Woehler Research Institute for Sustainable Chemistry (WISCh), Georg-August-Universität Göttingen, Tammannstraße 2, 37077, Göttingen, Germany
| | - Zhipeng Lin
- Institut für Organische und Biomolekulare Chemie and Woehler Research Institute for Sustainable Chemistry (WISCh), Georg-August-Universität Göttingen, Tammannstraße 2, 37077, Göttingen, Germany
| | - Lutz Ackermann
- Institut für Organische und Biomolekulare Chemie and Woehler Research Institute for Sustainable Chemistry (WISCh), Georg-August-Universität Göttingen, Tammannstraße 2, 37077, Göttingen, Germany
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8
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Peng TY, Xu ZY, Zhang FL, Li B, Xu WP, Fu Y, Wang YF. Dehydroxylative Alkylation of α‐Hydroxy Carboxylic Acids Derivatives via Spin‐center Shift. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202201329] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Tian-Yu Peng
- University of Science and Technology of China Department of Chemistry CHINA
| | - Zhe-Yuan Xu
- University of Science and Technology of China Department of Chemistry CHINA
| | - Feng-Lian Zhang
- University of Science and Technology of China Department of Chemistry CHINA
| | - Bin Li
- University of Science and Technology of China Department of Chemistry CHINA
| | - Wen-Ping Xu
- University of Science and Technology of China Department of Chemistry CHINA
| | - Yao Fu
- University of Science and Technology of China Department of Chemistry CHINA
| | - Yi-Feng Wang
- University of Science and Technology of China Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry 96 Jinzhai Road 230026 Hefei CHINA
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9
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Tan Z, He X, Xu K, Zeng C. Electrophotocatalytic C-H Functionalization of N-Heteroarenes with Unactivated Alkanes under External Oxidant-Free Conditions. CHEMSUSCHEM 2022; 15:e202102360. [PMID: 34967138 DOI: 10.1002/cssc.202102360] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/29/2021] [Indexed: 06/14/2023]
Abstract
The Minisci alkylation of N-heteroarenes with unactivated alkanes under external oxidant-free conditions provides an economically attractive route to access alkylated N-heteroarenes but remains underdeveloped. Herein, a new electrophotocatalytic strategy to access alkyl radicals from strong C(sp3 )-H bonds was reported for the following Minisci alkylation reactions in the absence of chemical oxidants. This strategy realized the first example of cerium-catalyzed Minisci alkylation reaction directly from abundant unactivated alkanes with excellent atom economy. It is anticipated that the general design principle would enrich catalytic strategies to explore the functionalizations of strong C(sp3 )-H bonds under external oxidant-free conditions with H2 evolution.
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Affiliation(s)
- Zhoumei Tan
- Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124, P.R. China
| | - Xinrui He
- Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124, P.R. China
| | - Kun Xu
- Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124, P.R. China
| | - Chengchu Zeng
- Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124, P.R. China
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10
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Sadowski B, Yuan B, Lin Z, Ackermann L. Rhodaelectro‐catalyzed peri‐selective direct alkenylations with weak O‐coordination enabled by hydrogen evolution reaction (HER). Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202117188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
| | - Binbin Yuan
- University of Göttingen: Georg-August-Universitat Gottingen IOBC GERMANY
| | - Zhipeng Lin
- University of Göttingen: Georg-August-Universitat Gottingen IOBC GERMANY
| | - Lutz Ackermann
- Georg-August-Universitaet Goettingen Institut fuer Organische und Biomolekulare Chemie Tammannstr. 2 37077 Goettingen GERMANY
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11
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Li H, Wenger OS. Photophysics of Perylene Diimide Dianions and Their Application in Photoredox Catalysis. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202110491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Han Li
- Department of Chemistry University of Basel St. Johanns-Ring 19 4056 Basel Switzerland
| | - Oliver S. Wenger
- Department of Chemistry University of Basel St. Johanns-Ring 19 4056 Basel Switzerland
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12
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Li H, Wenger OS. Photophysics of Perylene Diimide Dianions and Their Application in Photoredox Catalysis. Angew Chem Int Ed Engl 2021; 61:e202110491. [PMID: 34787359 PMCID: PMC9299816 DOI: 10.1002/anie.202110491] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 10/16/2021] [Indexed: 12/25/2022]
Abstract
The two‐electron reduced forms of perylene diimides (PDIs) are luminescent closed‐shell species whose photochemical properties seem underexplored. Our proof‐of‐concept study demonstrates that straightforward (single) excitation of PDI dianions with green photons provides an excited state that is similarly or more reducing than the much shorter‐lived excited states of PDI radical monoanions, which are typically accessible after biphotonic excitation with blue photons. Thermodynamically demanding photocatalytic reductive dehalogenations and reductive C−O bond cleavage reactions of lignin model compounds have been performed using sodium dithionite acts as a reductant, either in aqueous solution or in biphasic water–acetonitrile mixtures in the presence of a phase transfer reagent. Our work illustrates the concept of multi‐electron reduction of a photocatalyst by a sacrificial reagent prior to irradiation with low‐energy photons as a means of generating very reactive excited states.
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Affiliation(s)
- Han Li
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
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13
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Xu J, Cao J, Wu X, Wang H, Yang X, Tang X, Toh RW, Zhou R, Yeow EKL, Wu J. Unveiling Extreme Photoreduction Potentials of Donor-Acceptor Cyanoarenes to Access Aryl Radicals from Aryl Chlorides. J Am Chem Soc 2021; 143:13266-13273. [PMID: 34428911 DOI: 10.1021/jacs.1c05994] [Citation(s) in RCA: 74] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Since the seminal work of Zhang in 2016, donor-acceptor cyanoarene-based fluorophores, such as 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN), have been widely applied in photoredox catalysis and used as excellent metal-free alternatives to noble metal Ir- and Ru-based photocatalysts. However, all the reported photoredox reactions involving this chromophore family are based on harnessing the energy from a single visible light photon, with a limited range of redox potentials from -1.92 to +1.79 V vs SCE. Here, we document the unprecedented discovery that this family of fluorophores can undergo consecutive photoinduced electron transfer (ConPET) to achieve very high reduction potentials. One of the newly synthesized catalysts, 2,4,5-tri(9H-carbazol-9-yl)-6-(ethyl(phenyl)amino)isophthalonitrile (3CzEPAIPN), possesses a long-lived (12.95 ns) excited radical anion form, 3CzEPAIPN•-*, which can be used to activate reductively recalcitrant aryl chlorides (Ered ≈ -1.9 to -2.9 V vs SCE) under mild conditions. The resultant aryl radicals can be engaged in synthetically valuable aromatic C-B, C-P, and C-C bond formation to furnish arylboronates, arylphosphonium salts, arylphosphonates, and spirocyclic cyclohexadienes.
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Affiliation(s)
- Jinhui Xu
- Department of Chemistry, National University of Singapore, 117545 Singapore
| | - Jilei Cao
- College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China
| | - Xiangyang Wu
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore
| | - Han Wang
- Department of Chemistry, National University of Singapore, 117545 Singapore
| | - Xiaona Yang
- College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China
| | - Xinxin Tang
- Department of Chemistry, National University of Singapore, 117545 Singapore
| | - Ren Wei Toh
- Department of Chemistry, National University of Singapore, 117545 Singapore
| | - Rong Zhou
- College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China
| | - Edwin K L Yeow
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore
| | - Jie Wu
- Department of Chemistry, National University of Singapore, 117545 Singapore
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