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Li Q, Luo Y, Chen J, Xia Y. Visible-Light-Promoted Hydrogenation of Azobenzenes to Hydrazobenzenes with Thioacetic Acid as the Reductant. J Org Chem 2023; 88:2443-2452. [PMID: 36718625 DOI: 10.1021/acs.joc.2c02873] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A catalyst- and metal-free hydrogenation of azobenzenes to hydrazobenzenes in the presence of thioacetic acid was achieved under visible light irradiation. The transformation was carried out under mild conditions in an air atmosphere at ambient temperature, generating a variety of hydrazobenzenes with yields up to 99%. The current process is compatible with a variety of substituents and is highly chemoselective for azo reduction when other unsaturated functionalities (carbonyl, alkenyl, alkynyl, etc.) are contained. Preliminary mechanistic study indicated that the transformation could be a radical process.
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Affiliation(s)
- Qiao Li
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China
| | - Yanshu Luo
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China
| | - Jianhui Chen
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China
| | - Yuanzhi Xia
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China
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2
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Aziridination Reactivity of a Manganese(II) Complex with a Bulky Chelating Bis(Alkoxide) Ligand. Molecules 2022; 27:molecules27185751. [PMID: 36144492 PMCID: PMC9505844 DOI: 10.3390/molecules27185751] [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: 08/15/2022] [Revised: 08/30/2022] [Accepted: 08/30/2022] [Indexed: 11/17/2022] Open
Abstract
Treatment of Mn(N(SiMe3)2)2(THF)2 with bulky chelating bis(alkoxide) ligand [1,1′:4′,1′′-terphenyl]-2,2′′-diylbis(diphenylmethanol) (H2[O-terphenyl-O]Ph) formed a seesaw manganese(II) complex Mn[O-terphenyl-O]Ph(THF)2, characterized by structural, spectroscopic, magnetic, and analytical methods. The reactivity of Mn[O-terphenyl-O]Ph(THF)2 with various nitrene precursors was investigated. No reaction was observed between Mn[O-terphenyl-O]Ph(THF)2 and aryl azides. In contrast, the treatment of Mn[O-terphenyl-O]Ph(THF)2 with iminoiodinane PhINTs (Ts = p-toluenesulfonyl) was consistent with the formation of a metal-nitrene complex. In the presence of styrene, the reaction led to the formation of aziridine. Combining varying ratios of styrene and PhINTs in different solvents with 10 mol% of Mn[O-terphenyl-O]Ph(THF)2 at room temperature produced 2-phenylaziridine in up to a 79% yield. Exploration of the reactivity of Mn[O-terphenyl-O]Ph(THF)2 with various olefins revealed (1) moderate aziridination yields for p-substituted styrenes, irrespective of the electronic nature of the substituent; (2) moderate yield for 1,1′-disubstituted α-methylstyrene; (3) no aziridination for aliphatic α-olefins; (4) complex product mixtures for the β-substituted styrenes. DFT calculations suggest that iminoiodinane is oxidatively added upon binding to Mn, and the resulting formal imido intermediate has a high-spin Mn(III) center antiferromagnetically coupled to an imidyl radical. This imidyl radical reacts with styrene to form a sextet intermediate that readily reductively eliminates the formation of a sextet Mn(II) aziridine complex.
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Mao W, Fehn D, Heinemann FW, Scheurer A, van Gastel M, Jannuzzi SAV, DeBeer S, Munz D, Meyer K. Umpolung in a Pair of Cobalt(III) Terminal Imido/Imidyl Complexes. Angew Chem Int Ed Engl 2022; 61:e202206848. [PMID: 35674679 PMCID: PMC9541304 DOI: 10.1002/anie.202206848] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Indexed: 11/12/2022]
Abstract
Reaction of the CoI complex [(TIMMNmes )CoI ](PF6 ) (1) (TIMMNmes =tris-[2-(3-mesityl-imidazolin-2-ylidene)-methyl]amine) with mesityl azide yields the CoIII imide [(TIMMNmes )CoIII (NMes)](PF6 ) (2). Oxidation of 2 with [FeCp2 ](PF6 ) provides access to a rare CoIII imidyl [(TIMMNmes )Co(NMes)](PF6 )2 (3). Single-crystal X-ray diffractometry and EPR spectroscopy confirm the molecular structure of 3 and its S= 1 / 2 ground state. ENDOR, X-ray absorption spectroscopy and computational analyses indicate a ligand-based oxidation; thus, an imidyl-radical electronic structure for 3. Migratory insertion of one ancillary NHC to the imido ligand in 2 gives the CoI N-heterocyclic imine (4) within 12 h. Conversely, it takes merely 0.5 h for 3 to transform to the CoII congener (5). The migratory insertion in 2 occurs via a nucleophilic attack of the imido ligand at the NHC to give 4, whereas in 3, a nucleophilic attack of the NHC at the electrophilic imidyl ligand yields 5. The reactivity shunt upon oxidation of 2 to 3 confirms an umpolung of the imido ligand.
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Affiliation(s)
- Weiqing Mao
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
| | - Dominik Fehn
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
| | - Frank W. Heinemann
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
| | - Andreas Scheurer
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
| | - Maurice van Gastel
- Max-Planck-Institut für KohlenforschungKaiser-Wilhelm-Platz 145470Mülheim an der RuhrGermany
| | - Sergio A. V. Jannuzzi
- Max Planck Institute for Chemical Energy ConversionStiftstr. 34–3645470Mülheim an der RuhrGermany
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy ConversionStiftstr. 34–3645470Mülheim an der RuhrGermany
| | - Dominik Munz
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
- Current address: Saarland UniversityInorganic Chemistry: Coordination ChemistryCampus C4.166123SaarbrückenGermany
| | - Karsten Meyer
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
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Nitrenium ion-based ipso-addition and ortho-cyclization of arenes under photo and iron dual-catalysis. MOLECULAR CATALYSIS 2022. [DOI: 10.1016/j.mcat.2022.112413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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5
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Mao W, Fehn D, Heinemann FW, Scheurer A, van Gastel M, Jannuzzi SAV, DeBeer S, Munz D, Meyer K. Umpolung in a Pair of Cobalt(III) Terminal Imido/Imidyl Complexes. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202206848] [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)
- Weiqing Mao
- Friedrich-Alexander-Universität Erlangen-Nürnberg: Friedrich-Alexander-Universitat Erlangen-Nurnberg Department of Chemistry and Pharmacy GERMANY
| | - Dominik Fehn
- Friedrich-Alexander-Universität Erlangen-Nürnberg: Friedrich-Alexander-Universitat Erlangen-Nurnberg Department of Chemistry and Pharmacy GERMANY
| | - Frank W. Heinemann
- Friedrich-Alexander-Universität Erlangen-Nürnberg: Friedrich-Alexander-Universitat Erlangen-Nurnberg Department of Chemistry and Pharmacy GERMANY
| | - Andreas Scheurer
- Friedrich-Alexander-Universität Erlangen-Nürnberg: Friedrich-Alexander-Universitat Erlangen-Nurnberg Department of Chemistry and Pharmacy GERMANY
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung: Max-Planck-Institut fur Kohlenforschung Spectroscopy GERMANY
| | | | - Serena DeBeer
- Max-Planck-Institut für chemische Energiekonversion: Max-Planck-Institut fur chemische Energiekonversion Spectroscopy GERMANY
| | - Dominik Munz
- Saarland University: Universitat des Saarlandes Inorganic Chemistry: Coordination Chemistry GERMANY
| | - Karsten Meyer
- Friedrich-Alexander-Universität Erlangen-Nürnberg: Friedrich-Alexander-Universitat Erlangen-Nurnberg Department Chemie und Pharmazie Anorganische ChemieEgerlandstr. 1 91058 Erlangen GERMANY
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Osisioma O, Patton LJ, Merugu R, Govorov D, Milbrandt MA, Jarus C, Karney WL, Gudmundsdottir AD. Formation of Stilbene Azo-Dimer by Direct Irradiation of p-Azidostilbene. Photochem Photobiol 2022; 99:605-615. [PMID: 35652751 DOI: 10.1111/php.13659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 05/30/2022] [Indexed: 11/27/2022]
Abstract
Triplet arylnitrenes may provide direct access to aryl azo-dimers, which have broad commercial applicability. Herein, the photolysis of p-azidostilbene (1) in argon-saturated methanol yielded stilbene azo-dimer (2) through the dimerization of triplet p-nitrenostilbene (3 1N). The formation of 3 1N was verified by electron paramagnetic resonance spectroscopy and absorption spectroscopy (λmax ~ 375 nm) in cryogenic 2-methyltetrahydrofuran matrices. At ambient temperature, laser flash photolysis of 1 in methanol formed 3 1N (λmax ~ 370 nm, 2.85 × 107 s-1 ). On shorter timescales, a transient absorption (λmax ~ 390 nm) that decayed with a similar rate constant (3.11 × 107 s-1 ) was assigned to a triplet excited state (T) of 1. Density functional theory calculations yielded three configurations for T of 1, with the unpaired electrons on the azido (TA ) or stilbene moiety (TTw , twisted and TFl , flat). The transient was assigned to TTw based on its calculated spectrum. CASPT2 calculations gave a singlet-triplet energy gap of 16.6 kcal/mol for 1N; thus, intersystem crossing of 1 1N to 3 1N is unlikely at ambient temperature, supporting the formation of 3 1N from T of 1. Thus, sustainable synthetic methods for aryl azo-dimers can be developed using the visible-light irradiation of aryl azides to form triplet arylnitrenes.
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Affiliation(s)
- Onyinye Osisioma
- Department of Chemistry, University of Cincinnati, PO Box 210172, Cincinnati, OH, 45221-0172, USA
| | - Leanna J Patton
- Department of Chemistry, University of Cincinnati, PO Box 210172, Cincinnati, OH, 45221-0172, USA
| | - Rajkumar Merugu
- Department of Chemistry, University of Cincinnati, PO Box 210172, Cincinnati, OH, 45221-0172, USA
| | - Dmitrii Govorov
- Department of Chemistry, University of Cincinnati, PO Box 210172, Cincinnati, OH, 45221-0172, USA
| | - Margaret A Milbrandt
- Department of Chemistry, University of Cincinnati, PO Box 210172, Cincinnati, OH, 45221-0172, USA
| | - Cassandra Jarus
- Department of Chemistry, University of Cincinnati, PO Box 210172, Cincinnati, OH, 45221-0172, USA
| | - William L Karney
- Department of Chemistry, University of San Francisco, 2130 Fulton Street, San Francisco, CA, 94117, USA
| | - Anna D Gudmundsdottir
- Department of Chemistry, University of Cincinnati, PO Box 210172, Cincinnati, OH, 45221-0172, USA
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Adrion DM, Lopez SA. Cross-conjugation controls the stabilities and photophysical properties of heteroazoarene photoswitches. Org Biomol Chem 2022; 20:5989-5998. [PMID: 35014651 DOI: 10.1039/d1ob02026a] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Azoarene photoswitches are versatile molecules that interconvert from their E-isomer to their Z-isomer with light. Azobenzene is a prototypical photoswitch but its derivatives can be poorly suited for in vivo applications such as photopharmacology due to undesired photochemical reactions promoted by ultraviolet light and the relatively short half-life (t1/2) of the Z-isomer (2 days). Experimental and computational studies suggest that these properties (λmax of the E isomer and t1/2 of the Z-isomer) are inversely related. We identified isomeric azobisthiophenes and azobisfurans from a high-throughput screening study of 1540 azoarenes as photoswitch candidates with improved λmax and t1/2 values relative to azobenzene. We used density functional theory to predict the activation free energies and vertical excitation energies of the E- and Z-isomers of 2,2- and 3,3-substituted azobisthiophenes and azobisfurans. The half-lives depend on whether the heterocycles are π-conjugated or cross-conjugated with the diazo π-bond. The 2,2-substituted azoarenes both have t1/2 values on the scale of 1 hour, while the 3,3-analogues have computed half-lives of 40 and 230 years (thiophene and furan, respectively). The 2,2-substituted heteroazoarenes have significantly higher λmax absorptions than their 3,3-substituted analogues: 76 nm for azofuran and 77 nm for azothiophene.
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Affiliation(s)
- Daniel M Adrion
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts, 02115, USA.
| | - Steven A Lopez
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts, 02115, USA.
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Kurup SS, Nasser S, Ward CL, Groysman S. Synthesis and structure of a new bulky bis-(alkoxide) ligand on a terphenyl platform. Acta Crystallogr E Crystallogr Commun 2022; 78:92-96. [PMID: 35079433 PMCID: PMC8739204 DOI: 10.1107/s2056989021013438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 12/18/2021] [Indexed: 12/02/2022]
Abstract
A new sterically bulky chelating bis-(alkoxide) ligand 3,3'-([1,1':4',1''-terphen-yl]-2,2''-di-yl)bis-(2,2,4,4-tetra-methyl-pentan-3-ol), (H2[OO]tBu), was prepared in a two-step process as the di-chloro-methane monosolvate, C36H50O2·CH2Cl2. The first step is a Suzuki-Miyaura coupling reaction between 2-bromo-phenyl-boronic acid and 1,4-di-iodo-benzene. The resulting 2,2''-di-bromo-1,1':4',1''-terphenyl was reacted with t BuLi and hexa-methyl-acetone to obtain the desired product. The crystal structure of H2[OO]tBu revealed an anti conformation of the [CPh2(OH)] fragments relative to the central phenyl. Furthermore, the hydroxyl groups point away from each other. Likely because of this anti-anti conformation, the attempts to synthesize first-row transition-metal complexes with H2[OO]tBu were not successful.
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Affiliation(s)
- Sudheer S. Kurup
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Sandra Nasser
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Cassandra L. Ward
- Lumigen Instrument Center, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Stanislav Groysman
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
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Groysman S, Kurup SS. Catalytic synthesis of azoarenes via metal-mediated nitrene coupling. Dalton Trans 2022; 51:4577-4589. [DOI: 10.1039/d2dt00228k] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Various valuable properties of azoarenes (“azo dyes”), including their vivid colors and their facile cis-trans photoisomerization, lead to their wide use in the chemical industry. As a result, ~700,000 metric...
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