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Di Terlizzi L, Protti S, Ravelli D, Fagnoni M. Diradicals Photogeneration from Chloroaryl‐Substituted Carboxylic Acids. Chemistry 2022; 28:e202200313. [PMID: 35226781 PMCID: PMC9313617 DOI: 10.1002/chem.202200313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Indexed: 11/25/2022]
Abstract
With the aim of generating new, thermally inaccessible diradicals, potentially able to induce a double‐strand DNA cleavage, the photochemistry of a set of chloroaryl‐substituted carboxylic acids in polar media was investigated. The photoheterolytic cleavage of the Ar−Cl bond occurred in each case to form the corresponding triplet phenyl cations. Under basic conditions, the photorelease of the chloride anion was accompanied by an intramolecular electron‐transfer from the carboxylate group to the aromatic radical cationic site to give a diradical species. This latter intermediate could then undergo CO2 loss in a structure‐dependent fashion, according to the stability of the resulting diradical, or abstract a hydrogen atom from the medium. In aqueous environment at physiological pH (pH=7.3), both a phenyl cation and a diradical chemistry was observed. The mechanistic scenario and the role of the various intermediates (aryl cations and diradicals) involved in the process was supported by computational analysis.
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Affiliation(s)
| | - Stefano Protti
- PhotoGreen LabDepartment of ChemistryV. Le Taramelli 1027100PaviaItaly
| | - Davide Ravelli
- PhotoGreen LabDepartment of ChemistryV. Le Taramelli 1027100PaviaItaly
| | - Maurizio Fagnoni
- PhotoGreen LabDepartment of ChemistryV. Le Taramelli 1027100PaviaItaly
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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.
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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.
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Zhang M, Ma H, Li B, Sun K, Lu H, Wang W, Cheng X, Li X, Ding Y, Hu A. Nucleophilic Addition to Diradicals Derived From Cycloaromatization of Maleimide‐Based Enediynes. ASIAN J ORG CHEM 2021. [DOI: 10.1002/ajoc.202100136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Mengsi Zhang
- Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science and Engineering East China University of Science and Technology Shanghai 200237 P. R. China
| | - Hailong Ma
- Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science and Engineering East China University of Science and Technology Shanghai 200237 P. R. China
| | - Baojun Li
- Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science and Engineering East China University of Science and Technology Shanghai 200237 P. R. China
| | - Ke Sun
- Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science and Engineering East China University of Science and Technology Shanghai 200237 P. R. China
| | - Haotian Lu
- Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science and Engineering East China University of Science and Technology Shanghai 200237 P. R. China
| | - Wenbo Wang
- Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science and Engineering East China University of Science and Technology Shanghai 200237 P. R. China
| | - Xiaoyu Cheng
- Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science and Engineering East China University of Science and Technology Shanghai 200237 P. R. China
| | - Xiaoxuan Li
- Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science and Engineering East China University of Science and Technology Shanghai 200237 P. R. China
| | - Yun Ding
- Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science and Engineering East China University of Science and Technology Shanghai 200237 P. R. China
| | - Aiguo Hu
- Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science and Engineering East China University of Science and Technology Shanghai 200237 P. R. China
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Tatebe CJ, Johnson SA, Zeller M, Bart SC. Generation of Tp*2U(N3) from a family of new uranium(III) alkyl complexes. J Organomet Chem 2018. [DOI: 10.1016/j.jorganchem.2017.09.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Crespi S, Protti S, Ravelli D, Merli D, Fagnoni M. Sugar-Assisted Photogeneration of Didehydrotoluenes from Chlorobenzylphosphonic Acids. J Org Chem 2017; 82:12162-12172. [PMID: 29019237 DOI: 10.1021/acs.joc.7b01963] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Irradiation of the three isomeric chlorobenzylphophonic acids in aqueous buffer led to a pH-dependent photochemistry. Under acidic conditions (pH = 2.5), photocleavage of the Ar-Cl bond occurred and a phenyl cation chemistry resulted. Under basic conditions (pH = 11), a photoinduced release of the chloride anion followed by the detachment of the metaphosphate anion gave α,n-didehydrotoluene diradicals (α,n-DHTs), potential DNA cleaving intermediates. At a physiological pH (pH = 7.2), both a cationic and a diradical reactivity took place depending on the phosphonic acid used. It is noteworthy that the complexation exerted by a monosaccharide (glucose or methylglucopyranoside) present in solution induced an exclusive formation of α,n-DHTs. The mechanistic scenario of the different photoreactivities occurring when changing the pH of the solution and the role of the various intermediates (phenyl cations, diradicals, etc.) in the process was studied by computational analysis.
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Affiliation(s)
- Stefano Crespi
- PhotoGreen Lab, 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
| | - Davide Ravelli
- PhotoGreen Lab, Department of Chemistry, University of Pavia , Viale Taramelli 12, 27100 Pavia, Italy
| | - Daniele Merli
- 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
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Pedroli C, Ravelli D, Protti S, Albini A, Fagnoni M. Singlet vs Triplet Reactivity of Photogenerated α,n-Didehydrotoluenes. J Org Chem 2017; 82:6592-6603. [DOI: 10.1021/acs.joc.7b00610] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Chiara Pedroli
- Department of Chemistry, PhotoGreen Lab, Viale
Taramelli 12, 27100 Pavia, Italy
| | - Davide Ravelli
- Department of Chemistry, PhotoGreen Lab, Viale
Taramelli 12, 27100 Pavia, Italy
| | - Stefano Protti
- Department of Chemistry, PhotoGreen Lab, Viale
Taramelli 12, 27100 Pavia, Italy
| | - Angelo Albini
- Department of Chemistry, PhotoGreen Lab, Viale
Taramelli 12, 27100 Pavia, Italy
| | - Maurizio Fagnoni
- Department of Chemistry, PhotoGreen Lab, Viale
Taramelli 12, 27100 Pavia, Italy
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Zhu R, Li MD, Du L, Phillips DL. Singlet versus Triplet Excited State Mediated Photoinduced Dehalogenation Reactions of Itraconazole in Acetonitrile and Aqueous Solutions. J Phys Chem B 2017; 121:2712-2720. [PMID: 28281345 DOI: 10.1021/acs.jpcb.6b11934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photoinduced dehalogenation of the antifungal drug itraconazole (ITR) in acetonitrile (ACN) and ACN/water mixed solutions was investigated using femtosecond and nanosecond time-resolved transient absorption (fs-TA and ns-TA, respectively) and nanosecond time-resolved resonance Raman spectroscopy (ns-TR3) experiments. An excited resonance energy transfer is found to take place from the 4-phenyl-4,5-dihydro-3H-1,2,4-triazol-3-one part of the molecule to the 1,3-dichlorobenzene part of the molecule when ITR is excited by ultraviolet light. This photoexcitation is followed by a fast carbon-halogen bond cleavage that leads to the generation of radical intermediates via either triplet and/or singlet excited states. It is found that the singlet excited state-mediated carbon-halogen cleavage is the predominant dehalogenation process in ACN solvent, whereas a triplet state-mediated carbon-halogen cleavage prefers to occur in the ACN/water mixed solutions. The singlet-to-triplet energy gap is decreased in the ACN/water mixed solvents and this helps facilitate an intersystem crossing process, and thus, the carbon-halogen bond cleavage happens mostly through an excited triplet state in the aqueous solutions examined. The ns-TA and ns-TR3 results also provide some evidence that radical intermediates are generated through a homolytic carbon-halogen bond cleavage via predominantly the singlet excited state pathway in ACN but via mainly the triplet state pathway in the aqueous solutions. In strong acidic solutions, protonation at the oxygen and/or nitrogen atoms of the 1,2,4-triazole-3-one group appears to hinder the dehalogenation reactions. This may offer the possibility that the phototoxicity of ITR due to the generation of aryl or halogen radicals can be reduced by protonation of certain moieties in suitably designed ITR halogen-containing derivatives.
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Affiliation(s)
- Ruixue Zhu
- Department of Chemistry, The University of Hong Kong , Pokfulam Road, Pokfulam, Hong Kong S.A.R., P. R. China
| | - Ming-de Li
- Department of Chemistry, The University of Hong Kong , Pokfulam Road, Pokfulam, Hong Kong S.A.R., P. R. China.,Department of Chemistry, Shantou University , Shantou 515063, China
| | - Lili Du
- Department of Chemistry, The University of Hong Kong , Pokfulam Road, Pokfulam, Hong Kong S.A.R., P. R. China
| | - David Lee Phillips
- Department of Chemistry, The University of Hong Kong , Pokfulam Road, Pokfulam, Hong Kong S.A.R., P. R. China
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Raviola C, Protti S, Ravelli D, Fagnoni M. (Hetero)aromatics from dienynes, enediynes and enyne–allenes. Chem Soc Rev 2016; 45:4364-90. [DOI: 10.1039/c6cs00128a] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Recent advances in the synthesis of (hetero)aromatics starting from polyenes, such as dienynes, enediynes and enyne–allenes, are discussed.
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Romero MA, González-Delgado JA, Arteaga JF. Synthesis of Stilbene Derivatives: A Comparative Study of their Antioxidant Activities. Nat Prod Commun 2015. [DOI: 10.1177/1934578x1501000731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
A series of structurally simple compounds belonging to thestilbene family were synthesized by means of a Ti(III)-mediated methodology that allows access, in an efficient manner, to derivatives of dihydrostilbene, E-stilbene, and stilbene oxide, with high yields. The antioxidant activity of these compounds has been evaluated by means of two electrochemical assays, which provide complementary information, showing that the majority of these stilbene analogs exhibit significant antioxidant activity dependent on the electronic structure and functionalization of the molecule in each case.
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Affiliation(s)
- Miguel A. Romero
- CIQSO - Center for Research in Sustainable Chemistry and Department of Chemical Engineering, Physical Chemistry, and Organic Chemistry, University of Huelva, Campus de El Carmen s/n, 21071 Huelva, Spain
| | - José A. González-Delgado
- CIQSO - Center for Research in Sustainable Chemistry and Department of Chemical Engineering, Physical Chemistry, and Organic Chemistry, University of Huelva, Campus de El Carmen s/n, 21071 Huelva, Spain
| | - Jesús F. Arteaga
- CIQSO - Center for Research in Sustainable Chemistry and Department of Chemical Engineering, Physical Chemistry, and Organic Chemistry, University of Huelva, Campus de El Carmen s/n, 21071 Huelva, Spain
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Ravelli D, Protti S, Fagnoni M. Photogenerated α,n-didehydrotoluenes from chlorophenylacetic acids at physiological pH. J Org Chem 2015; 80:852-8. [PMID: 25478725 DOI: 10.1021/jo502318v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aromatic diradicals are recognized as promising intermediates for DNA cleavage, but their formation has thus far been limited to the Bergman and Myers–Saito cycloaromatizations. We report here the phototriggered generation of all isomers of the potential DNA-cleaving α,n-didehydrotoluene diradicals at physiological pH, accomplished by the irradiation of chlorophenylacetic acids under mild conditions. The desired diradicals were formed upon photolysis of the chosen aromatic in aqueous phosphate buffer solution (pH = 7.3), with the consecutive elimination of biologically compatible chloride ion and carbon dioxide. Theoretical simulations reveal that the efficient decarboxylation of the primarily generated phenyl cations involves a previously not known diradical structure.
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