1
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Sneha M, Thornton GL, Lewis-Borrell L, Ryder ASH, Espley SG, Clark IP, Cresswell AJ, Grayson MN, Orr-Ewing AJ. Photoredox-HAT Catalysis for Primary Amine α-C-H Alkylation: Mechanistic Insight with Transient Absorption Spectroscopy. ACS Catal 2023; 13:8004-8013. [PMID: 37342833 PMCID: PMC10278065 DOI: 10.1021/acscatal.3c01474] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/17/2023] [Indexed: 06/23/2023]
Abstract
The synergistic use of (organo)photoredox catalysts with hydrogen-atom transfer (HAT) cocatalysts has emerged as a powerful strategy for innate C(sp3)-H bond functionalization, particularly for C-H bonds α- to nitrogen. Azide ion (N3-) was recently identified as an effective HAT catalyst for the challenging α-C-H alkylation of unprotected, primary alkylamines, in combination with dicyanoarene photocatalysts such as 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN). Here, time-resolved transient absorption spectroscopy over sub-picosecond to microsecond timescales provides kinetic and mechanistic details of the photoredox catalytic cycle in acetonitrile solution. Direct observation of the electron transfer from N3- to photoexcited 4CzIPN reveals the participation of the S1 excited electronic state of the organic photocatalyst as an electron acceptor, but the N3• radical product of this reaction is not observed. Instead, both time-resolved infrared and UV-visible spectroscopic measurements implicate rapid association of N3• with N3- (a favorable process in acetonitrile) to form the N6•- radical anion. Electronic structure calculations indicate that N3• is the active participant in the HAT reaction, suggesting a role for N6•- as a reservoir that regulates the concentration of N3•.
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Affiliation(s)
- Mahima Sneha
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
- Department
of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, United States
| | - Georgia L. Thornton
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
| | - Luke Lewis-Borrell
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
| | - Alison S. H. Ryder
- Centre
for Sustainable Chemical Technologies, University
of Bath, 1 South, Claverton Down, Bath BA2 7AY, U.K.
| | - Samuel G. Espley
- Department
of Chemistry, University of Bath, 1 South, Claverton Down, Bath BA2 7AY, U.K.
| | - Ian P. Clark
- Central
Laser Facility, Research Complex at Harwell, Science and Technology
Facilities Council, Rutherford Appleton
Laboratory, Harwell Oxford, Didcot OX11 0QX, U.K.
| | - Alexander J. Cresswell
- Department
of Chemistry, University of Bath, 1 South, Claverton Down, Bath BA2 7AY, U.K.
| | - Matthew N. Grayson
- Department
of Chemistry, University of Bath, 1 South, Claverton Down, Bath BA2 7AY, U.K.
| | - Andrew J. Orr-Ewing
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
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2
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Xian C, He J, He Y, Nie J, Yuan Z, Sun J, Martens WN, Qin J, Zhu HY, Zhang Z. High Nitrile Yields of Aerobic Ammoxidation of Alcohols Achieved by Generating •O 2- and Br • Radicals over Iron-Modified TiO 2 Photocatalysts. J Am Chem Soc 2022; 144:23321-23331. [PMID: 36516341 DOI: 10.1021/jacs.2c07061] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Catalytic ammoxidation of alcohols into nitriles is an essential reaction in organic synthesis. While highly desirable, conducting the synthesis at room temperature is challenging, using NH3 as the nitrogen source, O2 as the oxidant, and a catalyst without noble metals. Herein, we report robust photocatalysts consisting of Fe(III)-modified titanium dioxide (Fe/TiO2) for ammoxidation reactions at room temperature utilizing oxygen at atmospheric pressure, NH3 as the nitrogen source, and NH4Br as an additive. To the best of our knowledge, this is the first example of catalytic ammoxidation of alcohols over a photocatalyst using such cheap and benign materials. Various (hetero) aromatic nitriles were synthesized at high yields, and aliphatic alcohols could also be transformed into corresponding nitriles at considerable yields. The modification of TiO2 with Fe(III) facilitates the formation of active •O2- radicals and increases the adsorption of NH3 and amino intermediates on the catalyst, accelerating the ammoxidation to yield nitriles. The additive NH4Br impressively improves the catalytic efficiency via the formation of bromine radicals (Br•) from Br-, which works synergistically with •O2- to capture H• from Cα-H, which is present in benzyl alcohol and the intermediate aldimine (RCH═NH), to generate the active carbon-centered radicals. Further, the generation of Br• from the Br- additive consumes the photogenerated holes and OH• radicals to prevent over-oxidation, significantly improving the selectivity toward nitriles. This amalgamation of function and synergy of the Fe(III)-doped TiO2 and NH4Br reveals new opportunities for developing semiconductor-based photocatalytic systems for fine chemical synthesis.
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Affiliation(s)
- Chensheng Xian
- School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, P. R. China
| | - Jie He
- School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, P. R. China
| | - Yurong He
- School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, P. R. China
| | - Jiabao Nie
- School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, P. R. China
| | - Ziliang Yuan
- School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, P. R. China
| | - Jie Sun
- School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, P. R. China
| | - Wayde N Martens
- School of Chemistry and Physics, Queensland University of Technology, Brisbane, Queensland 4001, Australia
| | - Jingzhong Qin
- School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, P. R. China
| | - Huai-Yong Zhu
- School of Chemistry and Physics, Queensland University of Technology, Brisbane, Queensland 4001, Australia
| | - Zehui Zhang
- School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, P. R. China
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3
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Shee M, Singh NDP. Photogenerated Azido Radical Mediated Oxidation: Access to Carbonyl Functionality from Alcohols, Alkylarenes, and Olefins via Organophotoredox. Adv Synth Catal 2022. [DOI: 10.1002/adsc.202200242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Maniklal Shee
- Department of Chemistry Indian Institute of Technology Kharagpur 721302 Kharagpur West Bengal India
| | - N. D. Pradeep Singh
- Department of Chemistry Indian Institute of Technology Kharagpur 721302 Kharagpur West Bengal India
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4
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Shee M, Singh NDP. Chemical versatility of azide radical: journey from a transient species to synthetic accessibility in organic transformations. Chem Soc Rev 2022; 51:2255-2312. [PMID: 35229836 DOI: 10.1039/d1cs00494h] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The generation of azide radical (N3˙) occurs from its precursors primarily via a single electron transfer (SET) process or homolytic cleavage by chemical methods or advanced photoredox/electrochemical methods. This in situ generated transient open-shell species has unique characteristic features that set its reactivity. In the past, the azide radical was widely used for various studies in radiation chemistry as a 1e- oxidant of biologically important molecules, but now it is being exploited for synthetic applications based on its addition and intermolecular hydrogen atom transfer (HAT) abilities. Due to the significant role of nitrogen-containing molecules in synthesis, drug discovery, biological, and material sciences, the direct addition onto unsaturated bonds for the simultaneous construction of C-N bond with other (C-X) bonds are indeed worth highlighting. Moreover, the ability to generate O- or C-centered radicals by N3˙ via electron transfer (ET) and intermolecular HAT processes is also well documented. The purpose of controlling the reactivity of this short-lived intermediate in organic transformations drives us to survey: (i) the history of azide radical and its structural properties (thermodynamic, spectroscopic, etc.), (ii) chemical reactivities and kinetics, (iii) methods to produce N3˙ from various precursors, (iv) several significant azide radical-mediated transformations in the field of functionalization with unsaturated bonds, C-H functionalization via HAT, tandem, and multicomponent reaction with a critical analysis of underlying mechanistic approaches and outcomes, (v) concept of taming the reactivity of azide radicals for potential opportunities, in this review.
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Affiliation(s)
- Maniklal Shee
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India.
| | - N D Pradeep Singh
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India.
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5
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Gentleman AS, Lawson T, Ellis MG, Davis M, Turner-Dore J, Ryder ASH, Frosz MH, Ciaccia M, Reisner E, Cresswell AJ, Euser TG. Stern–Volmer analysis of photocatalyst fluorescence quenching within hollow-core photonic crystal fibre microreactors. Chem Commun (Camb) 2022; 58:10548-10551. [DOI: 10.1039/d2cc03996f] [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
Optofluidic microreactors enable Stern–Volmer analysis on nanolitre-scale photocatalyst–quencher mixtures. The method is used to measure bimolecular quenching coefficients for a photoredox-catalysed α-C–H alkylation reaction of primary alkylamines.
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Affiliation(s)
- Alexander S. Gentleman
- Nanophotonics Centre, The Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Takashi Lawson
- Nanophotonics Centre, The Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Matthew G. Ellis
- Nanophotonics Centre, The Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Molly Davis
- Nanophotonics Centre, The Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Jacob Turner-Dore
- Department of Chemistry, University of Bath, 1 South, Claverton Down, Bath, BA2 7AY, UK
| | - Alison S. H. Ryder
- Department of Chemistry, University of Bath, 1 South, Claverton Down, Bath, BA2 7AY, UK
| | - Michael H. Frosz
- Max Planck Institute for the Science of Light, Staudtstr. 2, 91058, Erlangen, Germany
| | - Maria Ciaccia
- Syngenta, Jealott's Hill Research Centre, Bracknell, Berkshire, RG52 6EY, UK
| | - Erwin Reisner
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | | | - Tijmen G. Euser
- Nanophotonics Centre, The Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
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6
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Sahoo S, Pal S. Copper-Catalyzed One-Pot Synthesis of Quinazolinones from 2-Nitrobenzaldehydes with Aldehydes: Application toward the Synthesis of Natural Products. J Org Chem 2021; 86:18067-18080. [PMID: 34813342 DOI: 10.1021/acs.joc.1c02343] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A novel, efficient, and atom-economical approach for the construction of quinazolinones from 2-nitrobenzaldehydes has been unveiled via copper-catalyzed nitrile formation, hydrolysis, and reduction in one pot for the first time. In this reaction, urea is used as a source of nitrogen for nitrile formation, hydrazine hydrate is used for both the reduction of the nitro group and the hydrolysis of nitrile, and atmospheric oxygen is used as the sole oxidant. The method portrays a wide substrate scope with good functional group tolerances. Moreover, this method was applied for the synthesis of schizocommunin, tryptanthrin, phaitanthrin-A, phaitanthrin-B, and 8H-quinazolino[4,3-b]quinazolin-8-one.
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Affiliation(s)
- Subrata Sahoo
- Organic Chemistry Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Argul, Odisha 752050, India
| | - Shantanu Pal
- Organic Chemistry Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Argul, Odisha 752050, India
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7
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Dong C, Huang L, Guan Z, Huang C, He Y. Visible‐Light‐Mediated Aerobic Oxidative C(
sp
3
)−C(
sp
3
) Bond Cleavage of Morpholine Derivatives Using 4CzIPN as a Photocatalyst. Adv Synth Catal 2021. [DOI: 10.1002/adsc.202100455] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Chun‐Lin Dong
- Key Laboratory of Applied Chemistry of Chongqing Municipality School of Chemistry and Chemical Engineering Southwest University Chongqing 400715 People's Republic of China
| | - Lan‐Qian Huang
- Key Laboratory of Applied Chemistry of Chongqing Municipality School of Chemistry and Chemical Engineering Southwest University Chongqing 400715 People's Republic of China
| | - Zhi Guan
- Key Laboratory of Applied Chemistry of Chongqing Municipality School of Chemistry and Chemical Engineering Southwest University Chongqing 400715 People's Republic of China
| | - Chu‐Sheng Huang
- Guangxi Teachers Education University Nanning 530001 People's Republic of China
| | - Yan‐Hong He
- Key Laboratory of Applied Chemistry of Chongqing Municipality School of Chemistry and Chemical Engineering Southwest University Chongqing 400715 People's Republic of China
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8
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Li P, Zhang T, Mushtaq MA, Wu S, Xiang X, Yan D. Research Progress in Organic Synthesis by Means of Photoelectrocatalysis. CHEM REC 2021; 21:841-857. [PMID: 33656241 DOI: 10.1002/tcr.202000186] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 02/17/2021] [Accepted: 02/17/2021] [Indexed: 01/20/2023]
Abstract
The rapid development of radical chemistry has spurred several innovative strategies for organic synthesis. The novel approaches for organic synthesis play a critical role in promoting and regulating the single-electron redox activity. Among them, photoelectrocatalysis (PEC) has attained considerable attention as the most promising strategy to convert organic compounds into fine chemicals. This review highlights the current progress in organic synthesis through PEC, including various catalytic reactions, catalyst systems and practical applications. The numerous catalytic reactions suffer the high overpotential and poor conversion efficiency, depending on the design of electrolyzers and the reaction mechanisms. We also considered the recent developments with special emphasis on scientific problems and efficient solutions, which enhance accessibility to utilize and further develop the photoelectrocatalytic technology for the specific chemical bonds formation and the fabrication of numerous catalytic systems.
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Affiliation(s)
- Pengyan Li
- Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, and Key Laboratory of Radiopharmaceuticals, Ministry of Education, Beijing Normal University, Beijing, 100875, P. R. China
| | - Tingting Zhang
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Muhammad Asim Mushtaq
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Siqin Wu
- Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, and Key Laboratory of Radiopharmaceuticals, Ministry of Education, Beijing Normal University, Beijing, 100875, P. R. China
| | - Xu Xiang
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Dongpeng Yan
- Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, and Key Laboratory of Radiopharmaceuticals, Ministry of Education, Beijing Normal University, Beijing, 100875, P. R. China.,College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
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9
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Murugesan K, Donabauer K, König B. Visible-Light-Promoted Metal-Free Synthesis of (Hetero)Aromatic Nitriles from C(sp 3 )-H Bonds*. Angew Chem Int Ed Engl 2021; 60:2439-2445. [PMID: 33053270 PMCID: PMC7898869 DOI: 10.1002/anie.202011815] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 09/29/2020] [Indexed: 01/18/2023]
Abstract
The metal-free activation of C(sp3 )-H bonds to value-added products is of paramount importance in organic synthesis. We report the use of the commercially available organic dye 2,4,6-triphenylpyrylium tetrafluoroborate (TPP) for the conversion of methylarenes to the corresponding aryl nitriles via a photocatalytic process. Applying this methodology, a variety of cyanobenzenes have been synthesized in good to excellent yield under metal- and cyanide-free conditions. We demonstrate the scope of the method with over 50 examples including late-stage functionalization of drug molecules (celecoxib) and complex structures such as l-menthol, amino acids, and cholesterol derivatives. Furthermore, the presented synthetic protocol is applicable for gram-scale reactions. In addition to methylarenes, selected examples for the cyanation of aldehydes, alcohols and oximes are demonstrated as well. Detailed mechanistic investigations have been carried out using time-resolved luminescence quenching studies, control experiments, and NMR spectroscopy as well as kinetic studies, all supporting the proposed catalytic cycle.
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Affiliation(s)
| | | | - Burkhard König
- Faculty of Chemistry and PharmacyUniversity of RegensburgGermany
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10
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Patel RI, Sharma S, Sharma A. Cyanation: a photochemical approach and applications in organic synthesis. Org Chem Front 2021. [DOI: 10.1039/d1qo00162k] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This review summarises the photocatalytic cyanation strategies to construct C(sp2)–CN, C(sp3)–CN and X–CN (X = N, S) bonds.
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Affiliation(s)
- Roshan I. Patel
- Department of Chemistry
- Indian Institute of Technology Roorkee
- Roorkee-247667
- India
| | - Shivani Sharma
- Department of Chemistry
- Indian Institute of Technology Roorkee
- Roorkee-247667
- India
| | - Anuj Sharma
- Department of Chemistry
- Indian Institute of Technology Roorkee
- Roorkee-247667
- India
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11
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Bryden MA, Zysman-Colman E. Organic thermally activated delayed fluorescence (TADF) compounds used in photocatalysis. Chem Soc Rev 2021; 50:7587-7680. [PMID: 34002736 DOI: 10.1039/d1cs00198a] [Citation(s) in RCA: 133] [Impact Index Per Article: 44.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Organic compounds that show Thermally Activated Delayed Fluorescence (TADF) have become wildly popular as next-generation emitters in organic light emitting diodes (OLEDs). Since 2016, a subset of these have found increasing use as photocatalysts. This review comprehensively highlights their potential by documenting the diversity of the reactions where an organic TADF photocatalyst can be used in lieu of a noble metal complex photocatalyst. Beyond the small number of TADF photocatalysts that have been used to date, the analysis conducted within this review reveals the wider potential of organic donor-acceptor TADF compounds as photocatalysts. A discussion of the benefits of compounds showing TADF for photocatalysis is presented, which paints a picture of a very promising future for organic photocatalyst development.
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Affiliation(s)
- Megan Amy Bryden
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK.
| | - Eli Zysman-Colman
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK.
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