1
|
Visible-Light Photocatalytic Reduction of Aryl Halides as a Source of Aryl Radicals. Molecules 2022; 27:molecules27175364. [PMID: 36080129 PMCID: PMC9458128 DOI: 10.3390/molecules27175364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 08/19/2022] [Accepted: 08/20/2022] [Indexed: 11/17/2022] Open
Abstract
Aryl- and heteroaryl units are present in a wide variety of natural products, pharmaceuticals, and functional materials. The method for reduction of aryl halides with ubiquitous distribution is highly sought after for late-stage construction of various aromatic compounds. The visible-light-driven reduction of aryl halides to aryl radicals by electron transfer provides an efficient, simple, and environmentally friendly method for the construction of aromatic compounds. This review summarizes the recent progress in the generation of aryl radicals by visible-light-driven reduction of aryl halides with metal complexes, organic compounds, semiconductors as catalysts, and alkali-assisted reaction system. The ability and mechanism of reduction of aromatic halides in various visible light induced systems are summarized, intending to illustrate a comprehensive introduction of this research topic to the readers.
Collapse
|
2
|
Stimuli-sensitive drug delivery systems for site-specific antibiotic release. Drug Discov Today 2022; 27:1698-1705. [DOI: 10.1016/j.drudis.2022.02.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 01/19/2022] [Accepted: 02/17/2022] [Indexed: 12/12/2022]
|
3
|
Di Terlizzi L, Roncari F, Crespi S, Protti S, Fagnoni M. Aryl-Cl vs heteroatom-Si bond cleavage on the route to the photochemical generation of σ,π-heterodiradicals. Photochem Photobiol Sci 2021; 21:667-685. [PMID: 34775550 DOI: 10.1007/s43630-021-00119-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 10/16/2021] [Indexed: 11/30/2022]
Abstract
The photochemistry of aryl chlorides having a X-SiMe3 group (X = O, NR, S, SiMe2) tethered to the aromatic ring has been investigated in detail, with the aim to generate valuable ϭ,π-heterodiradicals. Two competitive pathways arising from the excited triplet state of the aromatics have been observed, namely heterolysis of the aryl-chlorine bond and homolysis of the X-silicon bond. The former path is found in chlorinated phenols and anilines, whereas the latter is exclusive in the case of silylated thiophenols and aryl silanes. A combined experimental/computational approach was pursued to explain such a photochemical behavior.Graphical abstract.
Collapse
Affiliation(s)
- Lorenzo Di Terlizzi
- Department of Chemistry, PhotoGreen Lab, Viale Taramelli 12, 27100, Pavia, Italy
| | - Francesca Roncari
- Department of Chemistry, PhotoGreen Lab, Viale Taramelli 12, 27100, Pavia, Italy
| | - Stefano Crespi
- Stratingh Institute for Chemistry, Center for Systems Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Stefano Protti
- Department of Chemistry, PhotoGreen Lab, Viale Taramelli 12, 27100, Pavia, Italy
| | - Maurizio Fagnoni
- Department of Chemistry, PhotoGreen Lab, Viale Taramelli 12, 27100, Pavia, Italy.
| |
Collapse
|
4
|
Aerobic oxidation of C-H bonds to carboxylic acids enabled by decatungstate photocatalysis. GREEN SYNTHESIS AND CATALYSIS 2021. [DOI: 10.1016/j.gresc.2021.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
|
5
|
Capaldo L, Ravelli D, Fagnoni M. Direct Photocatalyzed Hydrogen Atom Transfer (HAT) for Aliphatic C-H Bonds Elaboration. Chem Rev 2021; 122:1875-1924. [PMID: 34355884 PMCID: PMC8796199 DOI: 10.1021/acs.chemrev.1c00263] [Citation(s) in RCA: 305] [Impact Index Per Article: 101.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
![]()
Direct photocatalyzed
hydrogen atom transfer (d-HAT) can be considered
a method of choice for the elaboration of
aliphatic C–H bonds. In this manifold, a photocatalyst (PCHAT) exploits the energy of a photon to trigger the homolytic
cleavage of such bonds in organic compounds. Selective C–H
bond elaboration may be achieved by a judicious choice of the hydrogen
abstractor (key parameters are the electronic character and the molecular
structure), as well as reaction additives. Different are the classes
of PCsHAT available, including aromatic ketones, xanthene
dyes (Eosin Y), polyoxometalates, uranyl salts, a metal-oxo porphyrin
and a tris(amino)cyclopropenium radical dication. The processes (mainly
C–C bond formation) are in most cases carried out under mild
conditions with the help of visible light. The aim of this review
is to offer a comprehensive survey of the synthetic applications of
photocatalyzed d-HAT.
Collapse
Affiliation(s)
- Luca Capaldo
- Flow Chemistry Group, Van't Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Davide Ravelli
- PhotoGreen Lab, Department of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
| | - Maurizio Fagnoni
- PhotoGreen Lab, Department of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
| |
Collapse
|
6
|
Jara N, Milán NS, Rahman A, Mouheb L, Boffito DC, Jeffryes C, Dahoumane SA. Photochemical Synthesis of Gold and Silver Nanoparticles-A Review. Molecules 2021; 26:4585. [PMID: 34361738 PMCID: PMC8348930 DOI: 10.3390/molecules26154585] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 07/26/2021] [Accepted: 07/27/2021] [Indexed: 01/08/2023] Open
Abstract
Nanomaterials have supported important technological advances due to their unique properties and their applicability in various fields, such as biomedicine, catalysis, environment, energy, and electronics. This has triggered a tremendous increase in their demand. In turn, materials scientists have sought facile methods to produce nanomaterials of desired features, i.e., morphology, composition, colloidal stability, and surface chemistry, as these determine the targeted application. The advent of photoprocesses has enabled the easy, fast, scalable, and cost- and energy-effective production of metallic nanoparticles of controlled properties without the use of harmful reagents or sophisticated equipment. Herein, we overview the synthesis of gold and silver nanoparticles via photochemical routes. We extensively discuss the effect of varying the experimental parameters, such as the pH, exposure time, and source of irradiation, the use or not of reductants and surfactants, reagents' nature and concentration, on the outcomes of these noble nanoparticles, namely, their size, shape, and colloidal stability. The hypothetical mechanisms that govern these green processes are discussed whenever available. Finally, we mention their applications and insights for future developments.
Collapse
Affiliation(s)
- Nicole Jara
- School of Biological Sciences and Engineering, Yachay Tech University, Hacienda San José s/n, San Miguel de Urcuquí 100119, Ecuador; (N.J.); (N.S.M.)
| | - Nataly S. Milán
- School of Biological Sciences and Engineering, Yachay Tech University, Hacienda San José s/n, San Miguel de Urcuquí 100119, Ecuador; (N.J.); (N.S.M.)
| | - Ashiqur Rahman
- Center for Midstream Management and Science, Lamar University, Beaumont, TX 77710, USA; (A.R.); (C.J.)
| | - Lynda Mouheb
- Laboratoire de Recherche de Chimie Appliquée et de Génie Chimique, Hasnaoua I, Université Mouloud Mammeri B.P.17 RP, Tizi-Ouzou 15000, Algeria;
| | - Daria C. Boffito
- Department of Chemical Engineering, Polytechnique Montréal, C.P. 6079, Succ. Centre-Ville, Montréal, QC H3C 3A7, Canada;
| | - Clayton Jeffryes
- Center for Midstream Management and Science, Lamar University, Beaumont, TX 77710, USA; (A.R.); (C.J.)
- Center for Advances in Water and Air Quality, The Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, TX 77710, USA
| | - Si Amar Dahoumane
- School of Biological Sciences and Engineering, Yachay Tech University, Hacienda San José s/n, San Miguel de Urcuquí 100119, Ecuador; (N.J.); (N.S.M.)
- Department of Chemical Engineering, Polytechnique Montréal, C.P. 6079, Succ. Centre-Ville, Montréal, QC H3C 3A7, Canada;
| |
Collapse
|
7
|
Photoinduced Processes as a Way to Sustainable Polymers and Innovation in Polymeric Materials. Polymers (Basel) 2021; 13:polym13142293. [PMID: 34301050 PMCID: PMC8309236 DOI: 10.3390/polym13142293] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/05/2021] [Accepted: 07/10/2021] [Indexed: 11/16/2022] Open
Abstract
Photoinduced processes have gained considerable attention in polymer science and have greatly implemented the technological developments of new products. Therefore, a large amount of research work is currently developed in this area: in this paper we illustrate the advantages of a chemistry driven by light, the present perspectives of the technology, and summarize some of our recent research works, honoring the memory of Prof. Aldo Priola who passed away in March 2021 and was one of the first scientists in Italy to contribute to the field.
Collapse
|
8
|
Bonesi S, Protti S, Fagnoni M. Photohomolysis and Photoheterolysis in Aryl Sulfonates and Aryl Phosphates. Chemistry 2021; 27:6315-6323. [PMID: 33481315 DOI: 10.1002/chem.202005426] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Indexed: 01/24/2023]
Abstract
The photochemical behaviour of selected aryl sulfonates and phosphates (ArOX) in polar and nonpolar media has been investigated by laser flash photolysis (LFP) experiments. Two main pathways have been identified, namely the photohomolysis of the ArO-X bond or the photoheterolysis of the Ar-OX bond depending on the nature of the leaving group (OX) and on the nature of the substituents on the aromatic ring. In nonpolar solvents the esters are quite photostable due to an efficient triplet deactivation. In polar solvents, the homolytic fragmentation of the ArO-S bond from the exited singlets was found in aryl sulfonates bearing moderately electron-donating groups as well as electron-withdrawing groups. In electron-rich aryl phosphates and sulfonates photoheterolysis of the Ar-OP/Ar-OS bond took place as the exclusive pathway.
Collapse
Affiliation(s)
- Sergio Bonesi
- Department of Chemistry, PhotoGreen Lab, University of Pavia, V. Le Taramelli 12, 27100, Pavia, Italy.,Departamento de Química Orgánica, CIHIDECAR-CONICET, Facultad de Ciencias Exactas y Naturales, University of Buenos Aires, 3er Piso, Pabellón 2, Ciudad Universitaria, Buenos Aires, 1428, Argentina
| | - Stefano Protti
- Department of Chemistry, PhotoGreen Lab, University of Pavia, V. Le Taramelli 12, 27100, Pavia, Italy
| | - Maurizio Fagnoni
- Department of Chemistry, PhotoGreen Lab, University of Pavia, V. Le Taramelli 12, 27100, Pavia, Italy
| |
Collapse
|
9
|
Bugaenko DI, Volkov AA, Karchava AV, Yurovskaya MA. Generation of aryl radicals by redox processes. Recent progress in the arylation methodology. RUSSIAN CHEMICAL REVIEWS 2021. [DOI: 10.1070/rcr4959] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Arylation methods based on the generation and use of aryl radicals have been a rapidly growing field of research in recent years and currently represent a powerful strategy for carbon – carbon and carbon – heteroatom bond formation. The progress in this field is related to advances in the methods for generation of aryl radicals. The currently used aryl radical precursors include aryl halides, aryldiazonium and diaryliodonium salts, arylcarboxylic acids and their derivatives, arylboronic acids, arylhydrazines, organosulfur(II, VI) compounds and some other compounds. Aryl radicals are generated under mild conditions by single electron reduction or oxidation of precursors induced by conventional reagents, visible light or electric current. A crucial role in the development of the radical arylation methodology belongs to photoredox processes either catalyzed by transition metal complexes or organic dyes or proceeding without catalysts. Unlike the conventional transition metal-catalyzed arylation methods, radical arylation reactions proceed very often at room temperature and have high functional group tolerance. Without claiming to be exhaustive, this review covers the most important advances of the current decade in the generation and synthetic applications of (het)aryl radicals. Examples of reactions are given and mechanistic insights are highlighted.
The bibliography includes 341 references.
Collapse
|
10
|
Qrareya H, Meazza L, Protti S, Fagnoni M. Metal-free synthesis of biarenes via photoextrusion in di(tri)aryl phosphates. Beilstein J Org Chem 2020; 16:3008-3014. [PMID: 33363669 PMCID: PMC7736689 DOI: 10.3762/bjoc.16.250] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 11/23/2020] [Indexed: 11/23/2022] Open
Abstract
A metal-free route for the synthesis of biarenes has been developed. The approach is based on the photoextrusion of a phosphate moiety occurring upon irradiation of biaryl- and triaryl phosphates. The reaction involves an exciplex as the intermediate and it is especially suitable for the preparation of electron-rich biarenes.
Collapse
Affiliation(s)
- Hisham Qrareya
- PhotoGreen Lab, Department of Chemistry, viale Taramelli 12, 27100 Pavia, Italy.,Industrial Chemistry Department, Arab American University, 240 Jenin 13, Zababdeh, Palestine
| | - Lorenzo Meazza
- PhotoGreen Lab, Department of Chemistry, viale Taramelli 12, 27100 Pavia, Italy
| | - Stefano Protti
- PhotoGreen Lab, Department of Chemistry, viale Taramelli 12, 27100 Pavia, Italy
| | - Maurizio Fagnoni
- PhotoGreen Lab, Department of Chemistry, viale Taramelli 12, 27100 Pavia, Italy
| |
Collapse
|
11
|
Jain A, Ameta C. Novel Way to Harness Solar Energy: Photo-Redox Catalysis in Organic Synthesis. KINETICS AND CATALYSIS 2020. [DOI: 10.1134/s002315842002007x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|
12
|
Yu K, Zhang H, Su C, Zhu Y. Visible-Light-Promoted Efficient Aerobic Dehydrogenation of N-Heterocycles by a Tiny Organic Semiconductor Under Ambient Conditions. European J Org Chem 2020. [DOI: 10.1002/ejoc.202000170] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Kunyi Yu
- Department of Chemistry; Tsinghua University; 100084 Beijing PR China
| | - Hanjie Zhang
- Department of Chemistry; Tsinghua University; 100084 Beijing PR China
| | - Chenliang Su
- International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Engineering Technology Research Center for 2D Materials Information Functional Devices and Systems of Guangdong Province; Institute of Microscale Optoelectronics; Shenzhen University; 518060 Shenzhen PR China
| | - Yongfa Zhu
- Department of Chemistry; Tsinghua University; 100084 Beijing PR China
| |
Collapse
|
13
|
Garbarino S, Protti S, Gabrielli S, Fagnoni M, Palmieri A, Ravelli D. Multi‐Step Continuous Flow Synthesis of β/γ‐Substituted Ketones. CHEMPHOTOCHEM 2018. [DOI: 10.1002/cptc.201800107] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Silvia Garbarino
- PhotoGreen Lab, Department of Chemistry University of Pavia V.Le Taramelli 12 27100 Pavia Italy
| | - Stefano Protti
- PhotoGreen Lab, Department of Chemistry University of Pavia V.Le Taramelli 12 27100 Pavia Italy
| | - Serena Gabrielli
- Green Chemistry Group, School of Science and Technology Chemistry Division University of Camerino Via S. Agostino 1 62032 Camerino (MC) Italy
| | - Maurizio Fagnoni
- PhotoGreen Lab, Department of Chemistry University of Pavia V.Le Taramelli 12 27100 Pavia Italy
| | - Alessandro Palmieri
- Green Chemistry Group, School of Science and Technology Chemistry Division University of Camerino Via S. Agostino 1 62032 Camerino (MC) Italy
| | - Davide Ravelli
- PhotoGreen Lab, Department of Chemistry University of Pavia V.Le Taramelli 12 27100 Pavia Italy
| |
Collapse
|
14
|
Laudadio G, Govaerts S, Wang Y, Ravelli D, Koolman HF, Fagnoni M, Djuric SW, Noël T. Selective C(sp 3 )-H Aerobic Oxidation Enabled by Decatungstate Photocatalysis in Flow. Angew Chem Int Ed Engl 2018; 57:4078-4082. [PMID: 29451725 PMCID: PMC5900731 DOI: 10.1002/anie.201800818] [Citation(s) in RCA: 137] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Indexed: 11/09/2022]
Abstract
A mild and selective C(sp3 )-H aerobic oxidation enabled by decatungstate photocatalysis has been developed. The reaction can be significantly improved in a microflow reactor enabling the safe use of oxygen and enhanced irradiation of the reaction mixture. Our method allows for the oxidation of both activated and unactivated C-H bonds (30 examples). The ability to selectively oxidize natural scaffolds, such as (-)-ambroxide, pregnenolone acetate, (+)-sclareolide, and artemisinin, exemplifies the utility of this new method.
Collapse
Affiliation(s)
- Gabriele Laudadio
- Department of Chemical Engineering and ChemistryMicro Flow Chemistry and Process TechnologyEindhoven University of TechnologyDen Dolech 25612AZEindhovenThe Netherlands
| | - Sebastian Govaerts
- Department of Chemical Engineering and ChemistryMicro Flow Chemistry and Process TechnologyEindhoven University of TechnologyDen Dolech 25612AZEindhovenThe Netherlands
| | - Ying Wang
- Discovery Chemistry and TechnologiesAbbVie Inc.1 North Waukegan RoadNorth ChicagoIllinois60064USA
| | - Davide Ravelli
- PhotoGreen LabDepartment of ChemistryUniversity of PaviaViale Taramelli 1227100PaviaItaly
| | - Hannes F. Koolman
- Discovery Chemistry and TechnologiesAbbVie Inc.1 North Waukegan RoadNorth ChicagoIllinois60064USA
- Current affiliation: Medicinal ChemistryBoehringer Ingelheim Pharma GmbH & Co. KGBirkendorfer Strasse 6588397Biberach an der RissGermany
| | - Maurizio Fagnoni
- PhotoGreen LabDepartment of ChemistryUniversity of PaviaViale Taramelli 1227100PaviaItaly
| | - Stevan W. Djuric
- Discovery Chemistry and TechnologiesAbbVie Inc.1 North Waukegan RoadNorth ChicagoIllinois60064USA
| | - Timothy Noël
- Department of Chemical Engineering and ChemistryMicro Flow Chemistry and Process TechnologyEindhoven University of TechnologyDen Dolech 25612AZEindhovenThe Netherlands
| |
Collapse
|
15
|
Laudadio G, Govaerts S, Wang Y, Ravelli D, Koolman HF, Fagnoni M, Djuric SW, Noël T. Selective C(sp3
)−H Aerobic Oxidation Enabled by Decatungstate Photocatalysis in Flow. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201800818] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Gabriele Laudadio
- Department of Chemical Engineering and Chemistry; Micro Flow Chemistry and Process Technology; Eindhoven University of Technology; Den Dolech 2 5612 AZ Eindhoven The Netherlands
| | - Sebastian Govaerts
- Department of Chemical Engineering and Chemistry; Micro Flow Chemistry and Process Technology; Eindhoven University of Technology; Den Dolech 2 5612 AZ Eindhoven The Netherlands
| | - Ying Wang
- Discovery Chemistry and Technologies; AbbVie Inc.; 1 North Waukegan Road North Chicago Illinois 60064 USA
| | - Davide Ravelli
- PhotoGreen Lab; Department of Chemistry; University of Pavia; Viale Taramelli 12 27100 Pavia Italy
| | - Hannes F. Koolman
- Discovery Chemistry and Technologies; AbbVie Inc.; 1 North Waukegan Road North Chicago Illinois 60064 USA
- Current affiliation: Medicinal Chemistry; Boehringer Ingelheim Pharma GmbH & Co. KG; Birkendorfer Strasse 65 88397 Biberach an der Riss Germany
| | - Maurizio Fagnoni
- PhotoGreen Lab; Department of Chemistry; University of Pavia; Viale Taramelli 12 27100 Pavia Italy
| | - Stevan W. Djuric
- Discovery Chemistry and Technologies; AbbVie Inc.; 1 North Waukegan Road North Chicago Illinois 60064 USA
| | - Timothy Noël
- Department of Chemical Engineering and Chemistry; Micro Flow Chemistry and Process Technology; Eindhoven University of Technology; Den Dolech 2 5612 AZ Eindhoven The Netherlands
| |
Collapse
|
16
|
Raviola C, Fagnoni M. Search for a photoinduced (site-selective) cleavage of the Ar-Cl bond in dichloroanisoles. Photochem Photobiol Sci 2018; 17:107-117. [PMID: 29239452 DOI: 10.1039/c7pp00372b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The site-selective cleavage of an Ar-X bond in polyhalogenated aromatics is an important tool in synthetic planning especially when more than one identical halogen atom is present. An alternative to the usual metal-catalyzed cleavage is represented by photochemistry although only a few examples have been reported. We then investigated the feasibility of the site-selective photodechlorination of some dichloroanisoles through a combined experimental and computational study. In the case of 2,4-dichloroanisole, selective detachment of the chlorine atom at the ortho position with respect to the OMe group was observed upon photohomolysis (in cyclohexane) or photoheterolysis (in MeOH) of the Ar-Cl bond. In the latter case, 5-chloro-2-methoxy-1,1'-biphenyl was exclusively formed upon reaction of the resulting phenyl cation with benzene. The substitution of an OH group for a OMe group was detrimental since a lower photoreactivity resulted with no improvement in the selectivity.
Collapse
Affiliation(s)
- Carlotta Raviola
- PhotoGreen Lab, Department of Chemistry, V. Le Taramelli 12, 27100 Pavia, Italy.
| | | |
Collapse
|
17
|
Capaldo L, Riccardi R, Ravelli D, Fagnoni M. Acyl Radicals from Acylsilanes: Photoredox-Catalyzed Synthesis of Unsymmetrical Ketones. ACS Catal 2017. [DOI: 10.1021/acscatal.7b03719] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Luca Capaldo
- PhotoGreen Lab, Department
of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
| | - Riccardo Riccardi
- PhotoGreen Lab, Department
of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
| | - Davide Ravelli
- PhotoGreen Lab, Department
of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
| | - Maurizio Fagnoni
- PhotoGreen Lab, Department
of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
| |
Collapse
|
18
|
Neumeier M, Sampedro D, Májek M, de la Peña O'Shea VA, Jacobi von Wangelin A, Pérez-Ruiz R. Dichromatic Photocatalytic Substitutions of Aryl Halides with a Small Organic Dye. Chemistry 2017; 24:105-108. [PMID: 29131437 DOI: 10.1002/chem.201705326] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Indexed: 02/03/2023]
Abstract
Photocatalytic bond activations are generally limited by the photon energy and the efficiency of energy and electron transfer processes. Direct two-photon processes provide sufficient energy but the ultra-short lifetimes of the excited states prohibit chemical reactions. The commercial dye 9,10-dicyanoanthracene enabled photocatalytic aromatic substitutions of non-activated aryl halides. This reaction operates under VIS-irradiation via sequential photonic, electronic, and photonic activation of the simple organic dye. The resultant highly reducing excited photocatalyst anion readily effected C-H, C-C, C-P, C-S, and C-B bond formations. Detailed synthetic, spectroscopic, and theoretical studies support a biphotonic catalytic mechanism.
Collapse
Affiliation(s)
- Michael Neumeier
- Dept. of Chemistry, University of Regensburg, Universitaetsstr. 31, 93040, Regensburg, Germany
| | - Diego Sampedro
- Dept. of Chemistry, CISQ, University of La Rioja, C/Madre de Dios, 53, 26006, Logroño, La Rioja, Spain
| | - Michal Májek
- Dept. of Chemistry, University of Regensburg, Universitaetsstr. 31, 93040, Regensburg, Germany
| | | | - Axel Jacobi von Wangelin
- Dept. of Chemistry, University of Regensburg, Universitaetsstr. 31, 93040, Regensburg, Germany.,Dept. of Chemistry, University of Hamburg, Martin Luther King Pl 6, 20146, Hamburg, Germany
| | - Raúl Pérez-Ruiz
- Photoactivated Processes Unit, IMDEA Energy Institute, Ramón de la Sagra 3, 28935, Móstoles, Spain
| |
Collapse
|
19
|
|
20
|
Raviola C, Chiesa F, Protti S, Albini A, Fagnoni M. On the Route to the Photogeneration of Heteroaryl Cations. The Case of Halothiophenes. J Org Chem 2016; 81:6336-42. [PMID: 27383725 DOI: 10.1021/acs.joc.6b00978] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
2-Chloro-, 2-bromo-, and 2-iodothiophenes undergo photochemical dehalogenation via the triplet state. In the presence of suitable π-bond nucleophiles, thienylation occurs with modest yield from chloro and bromo derivatives (via photogenerated triplet 2-thienyl cation). Specific trapping by using oxygen along with computational analysis carried out by means of a density functional method support that, in the case of iodo derivatives, homolytic thienyl-I bond fragmentation occurs first and heteroaryl cations are formed by electron transfer within the triplet radical pair, thus opening an indirect access to such cations.
Collapse
Affiliation(s)
- Carlotta Raviola
- PhotoGreen Lab, Department of Chemistry, University of Pavia , Viale Taramelli 12, 27100 Pavia, Italy
| | - Francesco Chiesa
- Department of Chemistry, University of Pavia , Viale Taramelli 12, 27100 Pavia, Italy
| | - Stefano Protti
- PhotoGreen Lab, Department of Chemistry, University of Pavia , Viale Taramelli 12, 27100 Pavia, Italy
| | - Angelo Albini
- PhotoGreen Lab, Department of Chemistry, University of Pavia , Viale Taramelli 12, 27100 Pavia, Italy
| | - Maurizio Fagnoni
- PhotoGreen Lab, Department of Chemistry, University of Pavia , Viale Taramelli 12, 27100 Pavia, Italy
| |
Collapse
|