1
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Cheng Y, Huh DN, Tonks IA. Mechanistic study of pyrazole synthesis via oxidation-induced N-N coupling of diazatitanacycles. Dalton Trans 2024; 53:9510-9515. [PMID: 38767913 DOI: 10.1039/d4dt01412j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Metal-mediated inner-sphere N-N coupling is an uncommon route to N-N bond formation. Herein, we report a mechanistic study of pyrazole formation via oxidation-induced N-N coupling of diazatitanacycles. In TEMPO oxidation reactions, the first of two oxidations is rate limiting and TEMPO coordination to Ti is critical for reactivity. In oxidations with Fc+ salts, coordinating counteranions such (eg. Cl-) aid an "inner-sphere-like" oxidation.
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Affiliation(s)
- Yukun Cheng
- Department of Chemistry and Chemical Biology, Cornell University, 365 Spencer T. Olin Research Wing, Ithaca, New York, USA
| | - Daniel N Huh
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island, USA
| | - Ian A Tonks
- Department of Chemistry, University of Minnesota, 207 Pleasant St SE, Minneapolis, Minnesota, USA.
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2
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Tsurugi H, Akiyama T, Frye CW, Kakiuchi Y, Mashima K, Tonks IA. Evaluation of Tungsten Catalysis among Early Transition Metals for N-Aryl-2,3,4,5-tetraarylpyrrole Synthesis: Modular Access to N-Doped π-Conjugated Material Precursors. Inorg Chem 2024; 63:3037-3046. [PMID: 38300807 PMCID: PMC11059426 DOI: 10.1021/acs.inorgchem.3c03858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2024]
Abstract
Low-valent tungsten species generated from WCl6 and N,N'-bis(trimethylsilyl)-2,5-dimethyldihydropyrazine (Si-Me2-DHP) promotes the catalytic formation of N-phenyl-2,3,4,5-tetraarylpyrroles 3aa-ka from diarylacetylenes 1a-k and azobenzene (2a). An initial catalyst activation process is a three-electron reduction of WCl6 with Si-Me2-DHP to afford transient 'WCl3' species. Catalytically active bis(imido)tungsten(VI) species via successive one-electron reduction and N═N bond cleavage of 2a was revealed by isolating W(═NPh)2Cl2(PMe2Ph)2 from imidotungsten(V) trichloride and 2a in the presence of PMe2Ph. The superior catalytic activity of the tungsten catalyst was clarified by a density functional theory study: activation energies for the key three steps, [2 + 2]-cycloaddition of W═NPh and diarylacetylene to form (iminoalkylidene)tungsten species, enyne metathesis with second diarylacetylene, and C-N bond formation, are reasonable values for the catalytic reaction at 180 °C. In addition, this tungsten catalyst overcame two distinct deactivation processes: α-enediamido formation and aggregation of the low-valent species, both of which were observed for previously developed vanadium and titanium catalysts. We also demonstrated the synthetic utility of pentaarylpyrroles 3aa and 3ba as well as N-(2-bromophenyl)-2,3,4,5-tetraarylpyrrole 3ab by derivatizing their π-conjugated compounds 9aa, 10ba, and 11ab.
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Affiliation(s)
- Hayato Tsurugi
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
- Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
| | - Takuya Akiyama
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Connor W. Frye
- Department of Chemistry, University of Minnesota–Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Yuya Kakiuchi
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Kazushi Mashima
- Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka 565-0871, Japan
| | - Ian A. Tonks
- Department of Chemistry, University of Minnesota–Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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3
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Huh DN, Koby RF, Stuart ZE, Dunscomb RJ, Schley ND, Tonks IA. Reassessment of N 2 activation by low-valent Ti-amide complexes: a remarkable side-on bridged bis-N 2 adduct is actually an arene adduct. Chem Sci 2022; 13:13330-13337. [PMID: 36507167 PMCID: PMC9682900 DOI: 10.1039/d2sc04368h] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 10/13/2022] [Indexed: 12/15/2022] Open
Abstract
The complex {(TMEDA)2Li}{[Ti(N(TMS)2)2]2(μ-η2:η2-N2)2} (5-Li) is the only transition metal N2 complex ever reported with two side-on N2 adducts. In this report, the similarity of 5-Li to a new inverse sandwich toluene adduct {(PhMe)K}{[Ti(N(TMS)2)2]2(μ-PhMe)} (6-K) necessitated a re-examination of the structure of 5-Li. Through a reassessment of the original disordered crystal data of 5-Li and new independent syntheses brought about through revisitation of the original reaction conditions, 5-Li has been re-assigned as an inverse sandwich toluene adduct, {(TMEDA)2Li}{[Ti(N(TMS)2)2]2(μ-PhMe)} (6-Li). The original crystal data could be fitted almost equally well to structural solutions as either 5-Li or 6-Li, and this study highlights the importance of a holistic examination of modeled data and the need for secondary/complementary analytical methods in paramagnetic inorganic syntheses, especially when presenting unique and unexpected results. In addition, further examination of reduction reactions of Ti[N(TMS)2]3 and [(TMS)2N]2TiCl(THF) in the presence of KC8 revealed rich solvent- and counterion-dependent chemistry, including several degrees of N2 activation (bridging nitride complexes, terminal bridging N2 complexes) as well as ligand C-H activation.
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Affiliation(s)
- Daniel N Huh
- Department of Chemistry, University of Minnesota - Twin Cities Minneapolis MN 55455 USA
| | - Ross F Koby
- Department of Chemistry, University of Minnesota - Twin Cities Minneapolis MN 55455 USA
| | - Zoe E Stuart
- Department of Chemistry, University of Minnesota - Twin Cities Minneapolis MN 55455 USA
| | - Rachel J Dunscomb
- Department of Chemistry, University of Minnesota - Twin Cities Minneapolis MN 55455 USA
| | - Nathan D Schley
- Department of Chemistry, Vanderbilt University Nashville TN 37235 USA
| | - Ian A Tonks
- Department of Chemistry, University of Minnesota - Twin Cities Minneapolis MN 55455 USA
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4
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Cascade reaction of 3-formylchromones: Highly selective synthesis of 4-oxo-3-(1H-pyrrol-3-yl)-4H-chromenes. GREEN SYNTHESIS AND CATALYSIS 2022. [DOI: 10.1016/j.gresc.2022.10.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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5
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Roose TR, Verdoorn DS, Mampuys P, Ruijter E, Maes BUW, Orru RVA. Transition metal-catalysed carbene- and nitrene transfer to carbon monoxide and isocyanides. Chem Soc Rev 2022; 51:5842-5877. [PMID: 35748338 PMCID: PMC9580617 DOI: 10.1039/d1cs00305d] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2021] [Indexed: 11/21/2022]
Abstract
Transition metal-catalysed carbene- and nitrene transfer to the C1-building blocks carbon monoxide and isocyanides provides heteroallenes (i.e. ketenes, isocyanates, ketenimines and carbodiimides). These are versatile and reactive compounds allowing in situ transformation towards numerous functional groups and organic compounds, including heterocycles. Both one-pot and tandem processes have been developed providing valuable synthetic methods for the organic chemistry toolbox. This review discusses all known transition metal-catalysed carbene- and nitrene transfer reactions towards carbon monoxide and isocyanides and in situ transformation of the heteroallenes hereby obtained, with a special focus on the general mechanistic considerations.
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Affiliation(s)
- T R Roose
- Department of Chemistry and Pharmaceutical Sciences and Amsterdam Institute for Molecules, Medicines & Systems (AIMMS), Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands.
| | - D S Verdoorn
- Organic Chemistry, Aachen-Maastricht Institute for Biobased Materials (AMIBM), Maastricht University, Urmonderbaan 22, 6167RD Geleen, The Netherlands.
- Organic Synthesis Division, Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
| | - P Mampuys
- Organic Synthesis Division, Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
| | - E Ruijter
- Department of Chemistry and Pharmaceutical Sciences and Amsterdam Institute for Molecules, Medicines & Systems (AIMMS), Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands.
| | - B U W Maes
- Organic Synthesis Division, Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
| | - R V A Orru
- Organic Chemistry, Aachen-Maastricht Institute for Biobased Materials (AMIBM), Maastricht University, Urmonderbaan 22, 6167RD Geleen, The Netherlands.
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6
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Arango-Daza JC, Lluna-Galán C, Izquierdo-Aranda L, Cabrero-Antonino JR, Adam R. Heterogeneous Pd-Catalyzed Efficient Synthesis of Imidazolones via Dehydrogenative Condensation between Ureas and 1,2-Diols. ACS Catal 2022. [DOI: 10.1021/acscatal.2c01423] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Juan Camilo Arango-Daza
- Instituto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Av. de los Naranjos s/n, 46022 València, Spain
| | - Carles Lluna-Galán
- Instituto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Av. de los Naranjos s/n, 46022 València, Spain
| | - Luis Izquierdo-Aranda
- Instituto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Av. de los Naranjos s/n, 46022 València, Spain
| | - Jose R. Cabrero-Antonino
- Instituto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Av. de los Naranjos s/n, 46022 València, Spain
| | - Rosa Adam
- Instituto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Av. de los Naranjos s/n, 46022 València, Spain
- Departament de Química Orgànica, Facultat de Farmàcia, Universitat de València, Av. Vicent Andrés Estellés s/n, Burjassot, 46100 València, Spain
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7
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Shi Z, Mao W, Yang Z, Sun S, Tung CH, Xu Z. Au-catalyzed neighboring hydroxymethyl group directed cycloaddition of alkyne with diazadienes: Synthesis of polysubstituted pyrroles. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2022.05.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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Richards CA, Rath NP, Neely JM. Isolation and Reactivity of an Iron Azametallacyclobutene Complex. Organometallics 2022. [DOI: 10.1021/acs.organomet.2c00151] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Corey A. Richards
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri 63103, United States
| | - Nigam P. Rath
- Department of Chemistry and Biochemistry, University of Missouri-St. Louis, Saint Louis, Missouri 63121, United States
| | - Jamie M. Neely
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri 63103, United States
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9
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de Vries F, Otten E. Reversible On/Off Switching of Lactide Cyclopolymerization with a Redox-Active Formazanate Ligand. ACS Catal 2022; 12:4125-4130. [PMID: 35391903 PMCID: PMC8981207 DOI: 10.1021/acscatal.1c05689] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/18/2022] [Indexed: 12/17/2022]
Abstract
![]()
Redox-switching of
a formazanate zinc catalyst in ring-opening
polymerization (ROP) of lactide is described. Using a redox-active
ligand bound to an inert metal ion (Zn2+) allows modulation
of the catalytic activity by reversible reduction/oxidation chemistry
at a purely organic fragment. A combination of kinetic and spectroscopic
studies, together with mass spectrometry of the catalysis mixture,
provides insight in the nature of the active species and the initiation
of lactide ring-opening polymerization. The mechanistic data highlight
the key role of the redox-active ligand and provide a rationale for
the formation of cyclic polymer.
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Affiliation(s)
- Folkert de Vries
- Stratingh Institute for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Edwin Otten
- Stratingh Institute for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
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10
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Ren M, Wang YC, Ren S, Huang K, Liu JB, Qiu G. Metal‐Enabled Romance of Nitrene with Alkyne: Beyond Gold Catalysis. ChemCatChem 2022. [DOI: 10.1002/cctc.202200008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Miaofeng Ren
- JiangXi University of Science and Technology Chemistry CHINA
| | - Yu-Chao Wang
- JiangXi University of Science and Technology Chemistry CHINA
| | - Shangfeng Ren
- JiangXi University of Science and Technology Chemistry CHINA
| | - Keke Huang
- JiangXi University of Science and Technology Chemistry CHINA
| | - Jin-Biao Liu
- JiangXi University of Science and Technology faculty of Materials Metallurgy and Chemistry No.86,Hongqi Ave. 341000 Ganzhou CHINA
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11
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Shi X, Li S, Reiß M, Spannenberg A, Holtrichter-Rößmann T, Reiß F, Beweries T. 1-Zirconacyclobuta-2,3-dienes: synthesis of organometallic analogs of elusive 1,2-cyclobutadiene, unprecedented intramolecular C-H activation, and reactivity studies. Chem Sci 2021; 12:16074-16084. [PMID: 35024129 PMCID: PMC8672727 DOI: 10.1039/d1sc06052j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 11/22/2021] [Indexed: 01/25/2023] Open
Abstract
The structure, bonding, and reactivity of small, highly unsaturated ring systems is of fundamental interest for inorganic and organic chemistry. Four-membered metallacyclobuta-2,3-dienes, also referred to as metallacycloallenes, are among the most exotic examples for ring systems as these represent organometallic analogs of 1,2-cyclobutadiene, the smallest cyclic allene. Herein, the synthesis of the first examples of 1-zirconacyclobuta-2,3-dienes of the type [Cp'2Zr(Me3SiC3SiMe3)] (Cp'2 = rac-(ebthi), (ebthi = 1,2-ethylene-1,1'-bis(η5-tetrahydroindenyl)) (2a); rac-Me2Si(thi)2, thi = (η5-tetrahydroindenyl), (2b)) is presented. Both complexes undergo selective thermal C-H activation at the 7-position of the ansa-cyclopentadienyl ligand to produce a new type of "tucked-in" zirconocene system, 3a and 3b, that possesses a η3-propargyl/allenyl ligand. Both types of complexes react with carbonyl compounds, producing enynes in the case of 2a and 2b, as well as η1-allenyl complexes for 3a and 3b. Computational analysis of the structure and bonding of 2a and 3a reveals significant differences to a previously described related Ti complex. All complexes were fully characterised, including X-ray crystallography and experimental results were supported by DFT analysis.
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Affiliation(s)
- Xinzhe Shi
- Leibniz-Institut für Katalyse e.V. Albert-Einstein-Str. 29a 18059 Rostock Germany
| | - Sihan Li
- Leibniz-Institut für Katalyse e.V. Albert-Einstein-Str. 29a 18059 Rostock Germany
| | - Melanie Reiß
- Leibniz-Institut für Katalyse e.V. Albert-Einstein-Str. 29a 18059 Rostock Germany
| | - Anke Spannenberg
- Leibniz-Institut für Katalyse e.V. Albert-Einstein-Str. 29a 18059 Rostock Germany
| | | | - Fabian Reiß
- Leibniz-Institut für Katalyse e.V. Albert-Einstein-Str. 29a 18059 Rostock Germany
| | - Torsten Beweries
- Leibniz-Institut für Katalyse e.V. Albert-Einstein-Str. 29a 18059 Rostock Germany
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12
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Zhizhko PA, Bushkov NS, Pichugov AV, Zarubin DN. Oxo/imido heterometathesis: From molecular stoichiometric studies to well-defined heterogeneous catalysts. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2021.214112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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13
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Shi G, Sun J, Chen Z. One‐Pot Electro‐Oxidative Annulation Reactions: Synthesis of Polysubstituted Pyrroles from Anilines and Alkynoates. ChemistrySelect 2021. [DOI: 10.1002/slct.202102593] [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)
- Guang Shi
- College of Pharmaceutical Sciences Zhejiang University of Technology Hangzhou 310014 P.R. China
| | - Jie Sun
- College of Pharmaceutical Sciences Zhejiang University of Technology Hangzhou 310014 P.R. China
| | - Zhiwei Chen
- College of Pharmaceutical Sciences Zhejiang University of Technology Hangzhou 310014 P.R. China
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14
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Fischer M, Manßen M, Schmidtmann M, Klüner T, Beckhaus R. Selective propargylic C(sp 3)-H activation of methyl-substituted alkynes versus [2 + 2] cycloaddition at a titanium imido template. Chem Sci 2021; 12:13711-13718. [PMID: 34760155 PMCID: PMC8549805 DOI: 10.1039/d1sc04334j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Accepted: 09/27/2021] [Indexed: 11/29/2022] Open
Abstract
The reaction of the titanium imido complex 1b with 2-butyne leads to the formation of the titanium azadiene complex 2a at ambient temperature instead of yielding the archetypical [2 + 2] cycloaddition product (titanaazacyclobutene) which is usually obtained by combining titanium imido complexes and internal alkynes. The formation of 2a is presumably caused by an initial propargylic C(sp3)–H activation step and quantum chemical calculations suggest that the outcome of this unexpected reactivity is thermodynamically favored. The previously reported titanaazacyclobutene I (which is obtained by reacting 1b with 1-phenyl-1-propyne) undergoes a rearrangement reaction at elevated temperature to give the corresponding five-membered titanium azadiene complex 2b. An unexpected reactivity between a titanium imido complex and internal alkynes was unveiled yielding titanaazacyclobutenes instead of the expected [2 + 2] cycloaddition products.![]()
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Affiliation(s)
- Malte Fischer
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford South Parks Road Oxford OX1 3QR UK .,Institut für Chemie, Fakultät für Mathematik und Naturwissenschaften, Carl von Ossietzky Universität Oldenburg Postfach 2503 D-26111 Oldenburg Germany
| | - Manfred Manßen
- Anorganische Chemie Universität Tübingen Auf der Morgenstelle 18 D-72076 Tübingen Germany .,Institut für Chemie, Fakultät für Mathematik und Naturwissenschaften, Carl von Ossietzky Universität Oldenburg Postfach 2503 D-26111 Oldenburg Germany
| | - Marc Schmidtmann
- Institut für Chemie, Fakultät für Mathematik und Naturwissenschaften, Carl von Ossietzky Universität Oldenburg Postfach 2503 D-26111 Oldenburg Germany
| | - Thorsten Klüner
- Institut für Chemie, Fakultät für Mathematik und Naturwissenschaften, Carl von Ossietzky Universität Oldenburg Postfach 2503 D-26111 Oldenburg Germany
| | - Rüdiger Beckhaus
- Institut für Chemie, Fakultät für Mathematik und Naturwissenschaften, Carl von Ossietzky Universität Oldenburg Postfach 2503 D-26111 Oldenburg Germany
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15
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Schumacher C, Molitor C, Smid S, Truong KN, Rissanen K, Bolm C. Mechanochemical Syntheses of N-Containing Heterocycles with TosMIC. J Org Chem 2021; 86:14213-14222. [PMID: 34405999 DOI: 10.1021/acs.joc.1c01529] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A mechanochemical van Leusen pyrrole synthesis with a base leads to 3,4-disubstitued pyrroles in moderate to excellent yields. The developed protocol is compatible with a range of electron-withdrawing groups and can also be applied to the synthesis of oxazoles. Attempts to mechanochemically convert the resulting pyrroles into porphyrins proved to be difficult.
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Affiliation(s)
- Christian Schumacher
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany
| | - Claude Molitor
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany
| | - Sabrina Smid
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany
| | - Khai-Nghi Truong
- Department of Chemistry, University of Jyvaskyla, P.O. Box 35, Survontie 9 B, FI-40014 Jyväskylä, Finland
| | - Kari Rissanen
- Department of Chemistry, University of Jyvaskyla, P.O. Box 35, Survontie 9 B, FI-40014 Jyväskylä, Finland
| | - Carsten Bolm
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany
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16
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Fortier S, Gomez-Torres A. Redox chemistry of discrete low-valent titanium complexes and low-valent titanium synthons. Chem Commun (Camb) 2021; 57:10292-10316. [PMID: 34533140 DOI: 10.1039/d1cc02772g] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Titanium is a versatile metal that has important applications in practical synthesis, though this is typically limited to stoichiometric reactions or Lewis acid catalysis. Recently, interest has grown in using titanium and other early-metals for redox catalysis; however, notable limitations exist due to the thermodynamic preference of these metals to adopt high oxidation states. Nonetheless, discrete low-valent titanium (LVT) complexes and their synthons (titanium complexes which chemically behave as LVT sources) are known. Here, we detail the various ligand platforms that are capable of stabilizing LVT compounds and present the redox chemistry of these systems. This includes a discussion of recent developments in the use of LVT synthons for accessing fully reversible oxidative-addition/reductive-elimination reactions.
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Affiliation(s)
- Skye Fortier
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, TX 79968, USA.
| | - Alejandra Gomez-Torres
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, TX 79968, USA.
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17
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Sueyoshi S, Taniguchi T, Tanaka S, Asakawa H, Nishimura T, Maeda K. Understanding the Polymerization of Diphenylacetylenes with Tantalum(V) Chloride and Cocatalysts: Production of Cyclic Poly(diphenylacetylene)s by Low-Valent Tantalum Species Generated in Situ. J Am Chem Soc 2021; 143:16136-16146. [PMID: 34499837 DOI: 10.1021/jacs.1c06811] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A systematic investigation of the polymerization of representative diphenylacetylenes with TaCl5 and cocatalysts suggested that low-valent Ta species, which are formed by in situ reduction of TaCl5 by the cocatalysts, are involved in the polymerization and that the polymerization reaction proceeds by an insertion ring expansion mechanism via the formation of tantalacyclopentadiene intermediates, rather than the previously considered metathesis mechanism. This polymerization mechanism indicates the production of unprecedented cis-stereoregular cyclic poly(diphenylacetylene)s. Indeed, the possibilities of a cyclic structure and high cis-stereoregularity of the resulting polymers were reasonably supported by the results of their detailed atomic force microscopy (AFM) and NMR analyses, respectively.
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Affiliation(s)
- Shingyo Sueyoshi
- Graduate School of Frontier Science Initiative, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Tsuyoshi Taniguchi
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Saki Tanaka
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Hitoshi Asakawa
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.,Nanomaterials Research Institute (NanoMaRi), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.,Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Tatsuya Nishimura
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Katsuhiro Maeda
- Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.,Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
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18
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Abstract
Titanium is an attractive metal for catalytic reaction development: it is earth-abundant, inexpensive, and generally nontoxic. However-like most early transition metals-catalytic redox reactions with Ti are difficult because of the stability of the high-valent TiIV state. Understanding the fundamental mechanisms behind Ti redox processes is key for making progress toward potential catalytic applications. This Account details recent progress in Ti-catalyzed (and -mediated) oxidative amination reactions that proceed through formally TiII/TiIV catalytic cycles.This class of reactions is built on our initial discovery of Ti-catalyzed [2 + 2 + 1] pyrrole synthesis from alkynes and azobenzene, where detailed mechanistic studies have revealed important factors that allow for catalytic turnover despite the inherent difficulty of Ti redox. Two important conclusions from mechanistic studies are that (1) low-valent Ti intermediates in catalysis can be stabilized through coordination of π-acceptor substrates or products, where they can act as "redox-noninnocent" ligands through metal-to-ligand π back-donation, and (2) reductive elimination processes with Ti proceed through π-type electrocyclic (or pericyclic) reaction mechanisms rather than direct σ-bond coupling.The key reactive species in Ti-catalyzed oxidative amination reactions are Ti imidos (Ti≡NR), which can be generated from either aryl diazenes (RN═NR) or organic azides (RN3). These Ti imidos can then undergo [2 + 2] cycloadditions with alkynes, resulting in intermediates that can be coupled to an array of other unsaturated functional groups, including alkynes, alkenes, nitriles, and nitrosos. This basic reactivity pattern has been extended into a broad range of catalytic and stoichiometric oxidative multicomponent coupling reactions of alkynes and other reactive small molecules, leading to multicomponent syntheses of various heterocycles and aminated building blocks.For example, catalytic oxidative coupling of Ti imidos with two different alkynes leads to pyrroles, while stoichiometric oxidative coupling with alkynes and nitriles leads to pyrazoles. These heterocycle syntheses often yield substitution patterns that are complementary to those of classical condensation routes and provide access to new electron-rich, highly substituted heteroaromatic scaffolds. Furthermore, catalytic oxidative alkyne carboamination reactions can be accomplished via reaction of Ti imidos with alkynes and alkenes, yielding α,β-unsaturated imine or cyclopropylimine building blocks. New catalytic and stoichiometric oxidative amination methods such as alkyne α-diimination, isocyanide imination, and ring-opening oxidative amination of strained alkenes are continuously emerging as a result of better mechanistic understanding of Ti redox catalysis.Ultimately, these Ti-catalyzed and -mediated oxidative amination methods demonstrate the importance of examining often-overlooked elements like the early transition metals through the lens of modern catalysis: rather than a lack of utility, these elements frequently have undiscovered potential for new transformations with orthogonal or complementary selectivity to their late transition metal counterparts.
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Affiliation(s)
- Ian A. Tonks
- Department of Chemistry, University of Minnesota—Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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19
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Huh DN, Cheng Y, Frye CW, Egger DT, Tonks IA. Multicomponent syntheses of 5- and 6-membered aromatic heterocycles using group 4-8 transition metal catalysts. Chem Sci 2021; 12:9574-9590. [PMID: 34349931 PMCID: PMC8293814 DOI: 10.1039/d1sc03037j] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 06/28/2021] [Indexed: 12/31/2022] Open
Abstract
In this Perspective, we discuss recent syntheses of 5- and 6-membered aromatic heterocycles via multicomponent reactions (MCRs) that are catalyzed by group 4-8 transition metals. These MCRs can be categorized based on the substrate components used to generate the cyclized product, as well as on common mechanistic features between the catalyst systems. These particular groupings are intended to highlight mechanistic and strategic similarities between otherwise disparate transition metals and to encourage future work exploring related systems with otherwise-overlooked elements. Importantly, in many cases these early- to mid-transition metal catalysts have been shown to be as effective for heterocycle syntheses as the later (and more commonly implemented) group 9-11 metals.
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20
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Ye C, Jiao Y, Chiou MF, Li Y, Bao H. Direct synthesis of pentasubstituted pyrroles and hexasubstituted pyrrolines from propargyl sulfonylamides and allenamides. Chem Sci 2021; 12:9162-9167. [PMID: 34276946 PMCID: PMC8261710 DOI: 10.1039/d1sc02090k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 06/05/2021] [Indexed: 11/21/2022] Open
Abstract
Multisubstituted pyrroles are important fragments that appear in many bioactive small molecule scaffolds. Efficient synthesis of multisubstituted pyrroles with different substituents from easily accessible starting materials is challenging. Herein, we describe a metal-free method for the preparation of pentasubstituted pyrroles and hexasubstituted pyrrolines with different substituents and a free amino group by a base-promoted cascade addition-cyclization of propargylamides or allenamides with trimethylsilyl cyanide. This method would complement previous methods and support expansion of the toolbox for the synthesis of valuable, but previously inaccessible, highly substituted pyrroles and pyrrolines. Mechanistic studies to elucidate the reaction pathway have been conducted.
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Affiliation(s)
- Changqing Ye
- Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, State Key Laboratory of Structural Chemistry, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences 155 Yangqiao Road West Fuzhou Fujian 350002 People's Republic of China
| | - Yihang Jiao
- Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, State Key Laboratory of Structural Chemistry, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences 155 Yangqiao Road West Fuzhou Fujian 350002 People's Republic of China
| | - Mong-Feng Chiou
- Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, State Key Laboratory of Structural Chemistry, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences 155 Yangqiao Road West Fuzhou Fujian 350002 People's Republic of China
| | - Yajun Li
- Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, State Key Laboratory of Structural Chemistry, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences 155 Yangqiao Road West Fuzhou Fujian 350002 People's Republic of China
| | - Hongli Bao
- Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, State Key Laboratory of Structural Chemistry, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences 155 Yangqiao Road West Fuzhou Fujian 350002 People's Republic of China
- University of Chinese Academy of Sciences Beijing 100049 People's Republic of China
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21
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Haut FL, Feichtinger NJ, Plangger I, Wein LA, Müller M, Streit TN, Wurst K, Podewitz M, Magauer T. Synthesis of Pyrroles via Consecutive 6π-Electrocyclization/Ring-Contraction of Sulfilimines. J Am Chem Soc 2021; 143:9002-9008. [PMID: 34106724 PMCID: PMC8227482 DOI: 10.1021/jacs.1c04835] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Indexed: 12/20/2022]
Abstract
We present a modular, synthetic entry to polysubstituted pyrroles employing readily available 2,5-dihydrothiophenes. Ring-opening of the heterocycle provides access to a panel of 1,3-dienes which undergo pyrrole formation in the presence of inexpensive chloramine-T trihydrate. The transformation is conducted in an open flask and proceeds at ambient temperatures (23 °C) in nondry solvents. A careful adjustment of the electronics and sterics of the 1,3-diene precursor allows for the isolation of key intermediates. DFT studies identified a reaction mechanism that features a 6π-electrocyclization of a sulfilimine intermediate followed by spontaneous ring-contraction to reveal the pyrrole skeleton.
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Affiliation(s)
- Franz-Lucas Haut
- Institute
of Organic Chemistry and Center for Molecular Biosciences, Leopold-Franzens-University Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Niklas J. Feichtinger
- Institute
of Organic Chemistry and Center for Molecular Biosciences, Leopold-Franzens-University Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Immanuel Plangger
- Institute
of Organic Chemistry and Center for Molecular Biosciences, Leopold-Franzens-University Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Lukas A. Wein
- Institute
of Organic Chemistry and Center for Molecular Biosciences, Leopold-Franzens-University Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Mira Müller
- Institute
of Organic Chemistry and Center for Molecular Biosciences, Leopold-Franzens-University Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Tim-Niclas Streit
- Institute
of Organic Chemistry and Center for Molecular Biosciences, Leopold-Franzens-University Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Klaus Wurst
- Institute
of General, Inorganic and Theoretical Chemistry and Center for Molecular
Biosciences, Leopold-Franzens-University
Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Maren Podewitz
- Institute
of General, Inorganic and Theoretical Chemistry and Center for Molecular
Biosciences, Leopold-Franzens-University
Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Thomas Magauer
- Institute
of Organic Chemistry and Center for Molecular Biosciences, Leopold-Franzens-University Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
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22
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Lv ZJ, Chai Z, Zhu M, Wei J, Zhang WX. Selective Coupling of Lanthanide Metallacyclopropenes and Nitriles via Azametallacyclopentadiene and η 2-Pyrimidine Metallacycle. J Am Chem Soc 2021; 143:9151-9161. [PMID: 34029479 DOI: 10.1021/jacs.1c03604] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Exploring new lanthanide metallacycles and finding their unique chemistry different from the analogues of transition metals are of great interest and importance. In this work, we reported the synthesis, characterization, and reactivity toward nitriles of two lanthanide metallacyclopropenes: lutetacyclopropene 2a and dysprosacyclopropene 2b. The selective coupling of 2a and three molecules of PhCN was found for the first time to provide the unexpected fused lutetacycle 3a with one 1,6-dihydropyrimidine ring. Mechanistic studies by DFT calculations reveal that the triple insertion of PhCN into 2a proceeds through four key steps: the insertion of the first PhCN into 2a giving azalutetacyclopentadiene IM1, the insertion of the second PhCN into the Lu-N bond of IM1, the intramolecular electrocyclization providing a highly strained η2-pyrimidine metallacycle, and the insertion of the third PhCN into the Lu-Csp3 bond. Isolation and characterization of two active intermediates, azalutetacyclopentadiene IM1 and η2-pyrimidine dysprosacycle, provide critical evidence for the formation of 3a. Furthermore, IM1 was also reported to react with TMSCN, isocyanides, or W(CO)6 to furnish the fused [4,5] lutetacycles. The chemistry of two lanthanide metallacyclopropenes with nitriles is significantly different from these metallacyclopropenes of scandium and other metals. Most notably, the azalutetacyclopentadienes, η2-pyrimidine complex, and other metallacycles all represent the first examples in rare-earth organometallic chemistry; the formation of these new lutetacycles provides concrete evidence for understanding the mechanism of transition metal promoted or catalyzed [2+2+2] cycloaddition between alkynes and nitriles.
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Affiliation(s)
- Ze-Jie Lv
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Zhengqi Chai
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Miaomiao Zhu
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Junnian Wei
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Wen-Xiong Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
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23
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Wang K, Wu Q, Bi S, Liu L, Chen G, Li Y, James TD, Liu Y. Theoretical evaluation of the carbene-based site-selectivity in gold(III)-catalyzed annulations of alkynes with anthranils. Chem Commun (Camb) 2021; 57:1494-1497. [PMID: 33443276 DOI: 10.1039/d0cc07440c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The gold(iii)-catalyzed annulations of alkynes with anthranils were evaluated using DFT calculations. A unified rationale for the Br-migration on α-imino gold(iii)-carbene was proposed, from which an unprecedented "N-donation/abstraction substitution" mechanism was established using the substituted anthranils, while direct C-H nucleophilic attack was involved with the unsubstituted anthranils. The controlling factors guiding the site-selectivity were uncovered. These computational studies provide insight for developing new α-imino gold(iii)-carbene mediated reactions.
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Affiliation(s)
- Kaifeng Wang
- School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, 273165, P. R. China.
| | - Qiao Wu
- School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, 273165, P. R. China.
| | - Siwei Bi
- School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, 273165, P. R. China.
| | - Lingjun Liu
- School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, 273165, P. R. China.
| | - Guang Chen
- School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, 273165, P. R. China. and Ministry of Education, Key Laboratory of Hainan Trauma and Disaster Rescue, College of Emergency and Trauma, Hainan Medical University, Haikou 571199, China
| | - Yulin Li
- Key Laboratory of Tibetan Medicine Research & Qinghai Key Laboratory of Qinghai-Tibet Plateau Biological Resources, Northwest Institute of Plateau Biology, Chinese Academy of Science, Xining 810001, Qinghai, P. R. China
| | - Tony D James
- Department of Chemistry, University of Bath, Bath, UK BA2 7AY, UK and School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang 453007, P. R. China
| | - Yuxia Liu
- School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, 273165, P. R. China.
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24
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Lan S, Liu R, Kong X, Liu J, Luo B, Yang S, Fang X. Ti(O iPr) 4-Facilitated Formal Deoxygenative Annulation of Alkynyl 1,2-Diketones for the Synthesis of Highly Functionalized Furans. Org Lett 2021; 23:1504-1509. [PMID: 33534595 DOI: 10.1021/acs.orglett.1c00291] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A unique deoxygenative cyclodimerization of alkynyl 1,2-diketones facilitated by Ti(OiPr)4 is achieved, affording a series of highly functionalized furan products. An unusual C-C bond and C═O bond cleavage of the substrates is observed, and Ti(OiPr)4 plays triplicate roles in the reaction. Furthermore, the products show uncommon fluorescent emission in the solid state, indicating the potential practical applications of this work.
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Affiliation(s)
- Shouang Lan
- State Key Laboratory of Structural Chemistry and Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, University of Chinese Academy of Sciences, Fuzhou 350100, China
| | - Rui Liu
- State Key Laboratory of Structural Chemistry and Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, University of Chinese Academy of Sciences, Fuzhou 350100, China
| | - Xiangwen Kong
- State Key Laboratory of Structural Chemistry and Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, University of Chinese Academy of Sciences, Fuzhou 350100, China
| | - Jinggong Liu
- Orthopedics Department, Guangdong Provincial Hospital of Traditional Chinese Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510120, China
| | - Benlong Luo
- Pingxiang University, Pingxiang 337055, China
| | - Shuang Yang
- State Key Laboratory of Structural Chemistry and Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, University of Chinese Academy of Sciences, Fuzhou 350100, China
| | - Xinqiang Fang
- State Key Laboratory of Structural Chemistry and Key Laboratory of Coal to Ethylene Glycol and Its Related Technology, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, University of Chinese Academy of Sciences, Fuzhou 350100, China
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25
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Reinholdt A, Pividori D, Laughlin AL, DiMucci IM, MacMillan SN, Jafari MG, Gau MR, Carroll PJ, Krzystek J, Ozarowski A, Telser J, Lancaster KM, Meyer K, Mindiola DJ. A Mononuclear and High-Spin Tetrahedral Ti II Complex. Inorg Chem 2020; 59:17834-17850. [PMID: 33258366 PMCID: PMC7928263 DOI: 10.1021/acs.inorgchem.0c02586] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Indexed: 12/31/2022]
Abstract
A high-spin, mononuclear TiII complex, [(TptBu,Me)TiCl] [TptBu,Me- = hydridotris(3-tert-butyl-5-methylpyrazol-1-yl)borate], confined to a tetrahedral ligand-field environment, has been prepared by reduction of the precursor [(TptBu,Me)TiCl2] with KC8. Complex [(TptBu,Me)TiCl] has a 3A2 ground state (assuming C3v symmetry based on structural studies), established via a combination of high-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy, solution and solid-state magnetic studies, Ti K-edge X-ray absorption spectroscopy (XAS), and both density functional theory and ab initio (complete-active-space self-consistent-field, CASSCF) calculations. The formally and physically defined TiII complex readily binds tetrahydrofuran (THF) to form the paramagnetic adduct [(TptBu,Me)TiCl(THF)], which is impervious to N2 binding. However, in the absence of THF, the TiII complex captures N2 to produce the diamagnetic complex [(TptBu,Me)TiCl]2(η1,η1;μ2-N2), with a linear Ti═N═N═Ti topology, established by single-crystal X-ray diffraction. The N2 complex was characterized using XAS as well as IR and Raman spectroscopies, thus establishing this complex to possess two TiIII centers covalently bridged by an N22- unit. A π acid such as CNAd (Ad = 1-adamantyl) coordinates to [(TptBu,Me)TiCl] without inducing spin pairing of the d electrons, thereby forming a unique high-spin and five-coordinate TiII complex, namely, [(TptBu,Me)TiCl(CNAd)]. The reducing power of the coordinatively unsaturated TiII-containing [(ΤptBu,Me)TiCl] species, quantified by electrochemistry, provides access to a family of mononuclear TiIV complexes of the type [(TptBu,Me)Ti═E(Cl)] (with E2- = NSiMe3, N2CPh2, O, and NH) by virtue of atom- or group-transfer reactions using various small molecules such as N3SiMe3, N2CPh2, N2O, and the bicyclic amine 2,3:5,6-dibenzo-7-azabicyclo[2.2.1]hepta-2,5-diene.
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Affiliation(s)
- Anders Reinholdt
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Daniel Pividori
- Inorganic
Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander University (FAU) Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Alexander L. Laughlin
- Baker
Laboratory, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Ida M. DiMucci
- Baker
Laboratory, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Samantha N. MacMillan
- Baker
Laboratory, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Mehrafshan G. Jafari
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Michael R. Gau
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Patrick J. Carroll
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - J. Krzystek
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Andrew Ozarowski
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Joshua Telser
- Department
of Biological, Physical and Health Sciences, Roosevelt University, Chicago, Illinois 60605, United States
| | - Kyle M. Lancaster
- Baker
Laboratory, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Karsten Meyer
- Inorganic
Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander University (FAU) Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Daniel J. Mindiola
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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26
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Decarbonylative Issues Involved in Ru(II)‐Catalyzed [6+2−1] Annulation Reaction of Hydroxychromone with Alkyne: A DFT Study. European J Org Chem 2020. [DOI: 10.1002/ejoc.202001270] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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27
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See XY, Wen X, Wheeler TA, Klein CK, Goodpaster JD, Reiner BR, Tonks IA. Iterative Supervised Principal Component Analysis Driven Ligand Design for Regioselective Ti-Catalyzed Pyrrole Synthesis. ACS Catal 2020; 10:13504-13517. [PMID: 34327040 PMCID: PMC8318334 DOI: 10.1021/acscatal.0c03939] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The rational design of catalysts remains a challenging endeavor within the broader chemical community owing to the myriad variables that can affect key bond-forming events. Designing selective catalysts for any reaction requires an efficient strategy for discovering predictive structure-activity relationships. Herein, we describe the use of iterative supervised principal component analysis (ISPCA) in de novo catalyst design. The regioselective synthesis of 2,5-dimethyl-1,3,4-triphenyl-1H-pyrrole (C) via a Ti-catalyzed formal [2 + 2 +1] cycloaddition of phenylpropyne and azobenzene was targeted as a proof of principle. The initial reaction conditions led to an unselective mixture of all possible pyrrole regioisomers. ISPCA was conducted on a training set of catalysts, and their performance was regressed against the scores from the top three principal components. Component loadings from this PCA space and k-means clustering were used to inform the design of new test catalysts. The selectivity of a prospective test set was predicted in silico using the ISPCA model, and optimal candidates were synthesized and tested experimentally. This data-driven predictive-modeling workflow was iterated, and after only three generations the catalytic selectivity was improved from 0.5 (statistical mixture of products) to over 11 (>90% C) by incorporating 2,6-dimethyl-4-(pyrrolidin-1-yl)pyridine as a ligand. The origin of catalyst selectivity was probed by examining ISPCA variable loadings in combination with DFT modeling, revealing that ligand lability plays an important role in selectivity. A parallel catalyst search using multivariate linear regression (MLR), a popular approach in catalysis informatics, was also conducted in order to compare these strategies in a hypothetical catalyst scouting campaign. ISPCA appears to be more robust and predictive than MLR when sparse training sets are used that are representative of the data available during the early search for an optimal catalyst. The successful development of a highly selective catalyst without resorting to long, stochastic screening processes demonstrates the inherent power of ISPCA in de novo catalyst design and should motivate the general use of ISPCA in reaction development.
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Affiliation(s)
- Xin Yi See
- Department of Chemistry, University of Minnesota-Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Xuelan Wen
- Department of Chemistry, University of Minnesota-Twin Cities, Minneapolis, Minnesota 55455, United States
| | - T Alexander Wheeler
- Department of Chemistry, University of Minnesota-Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Channing K Klein
- Department of Chemistry, University of Minnesota-Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Jason D Goodpaster
- Department of Chemistry, University of Minnesota-Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Benjamin R Reiner
- Department of Chemistry, University of Minnesota-Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Ian A Tonks
- Department of Chemistry, University of Minnesota-Twin Cities, Minneapolis, Minnesota 55455, United States
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28
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Cheng Y, Klein CK, Tonks IA. Synthesis of pentasubstituted 2-aryl pyrroles from boryl and stannyl alkynes via one-pot sequential Ti-catalyzed [2 + 2 + 1] pyrrole synthesis/cross coupling reactions. Chem Sci 2020; 11:10236-10242. [PMID: 34094289 PMCID: PMC8162107 DOI: 10.1039/d0sc01576h] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 09/06/2020] [Indexed: 12/14/2022] Open
Abstract
Multisubstituted pyrroles are commonly found in many bioactive small molecule scaffolds, yet the synthesis of highly-substituted pyrrole cores remains challenging. Herein, we report an efficient catalytic synthesis of 2-heteroatom-substituted (9-BBN or SnR3) pyrroles via Ti-catalyzed [2 + 2 + 1] heterocoupling of heteroatom-substituted alkynes. In particular, the 9-BBN-alkyne coupling reactions were found to be very sensitive to Lewis basic ligands in the reaction: exchange of pyridine ligands from Ti to B inhibited catalysis, as evidenced by in situ 11B NMR studies. The resulting 2-boryl substituted pyrroles can then be used in Suzuki reactions in a one-pot sequential fashion, resulting in pentasubstituted 2-aryl pyrroles that are inaccessible via previous [2 + 2 + 1] heterocoupling strategies. This reaction provides a complementary approach to previous [2 + 2 + 1] heterocouplings of TMS-substituted alkynes, which could be further functionalized via electrophilic aromatic substitution.
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Affiliation(s)
- Yukun Cheng
- Department of Chemistry, University of Minnesota - Twin Cities 207 Pleasant St SE Minneapolis Minnesota 55455 USA
| | - Channing K Klein
- Department of Chemistry, University of Minnesota - Twin Cities 207 Pleasant St SE Minneapolis Minnesota 55455 USA
| | - Ian A Tonks
- Department of Chemistry, University of Minnesota - Twin Cities 207 Pleasant St SE Minneapolis Minnesota 55455 USA
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29
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Nickel-catalyzed formal [3 + 2]-cycloaddition of 2H-azirines with 1,3-dicarbonyl compounds for the synthesis of pyrroles. Tetrahedron Lett 2020. [DOI: 10.1016/j.tetlet.2020.152319] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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30
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Fischer M, Wolff MC, del Horno E, Schmidtmann M, Beckhaus R. Synthesis, Reactivity, and Insights into the Lewis Acidity of Mononuclear Titanocene Imido Complexes Bearing Sterically Demanding Terphenyl Moieties. Organometallics 2020. [DOI: 10.1021/acs.organomet.0c00452] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Malte Fischer
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock, D-18059 Rostock, Germany
| | - Marie Christin Wolff
- Institut für Chemie, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany
| | - Estefanía del Horno
- Departamento de Química Orgánica y Química Inorgánica, Universidad de Alcalá, 28805 Alcalá de Henares-Madrid, Spain
| | - Marc Schmidtmann
- Institut für Chemie, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany
| | - Rüdiger Beckhaus
- Institut für Chemie, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany
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31
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Ziółkowska A, Szynkiewicz N, Pikies J, Ponikiewski Ł. Solvent Impact on the Diversity of Products in the Reaction of Lithium Diphenylphosphide and a Ti(III) Complex Supported by a tBu 2P-P(SiMe 3) Ligand. Inorg Chem 2020; 59:11305-11315. [PMID: 32799493 PMCID: PMC7458418 DOI: 10.1021/acs.inorgchem.0c00824] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present two important trends in the reactivity of the titanium complex [MeNacNacTi(Cl){η2-P(SiMe3)-PtBu2}] (MeNacNac- = [Ar]NC(Me)CHC(Me)N[Ar]; Ar = 2,6-iPr2Ph) with nucleophilic reagents RLi (R = Ph2P, tBuO, (Me3Si)2N, and tBu2N) depending on the reaction medium. Reaction in nonpolar solvent (toluene) leads to three main products: via an autoredox process and nucleophilic substitution at the Ti-atom to afford the Ti(IV) complex [MeNacNacTi(R){η2-P-PtBu2}] (1 for R = PPh2), via the elimination of Me3SiR to afford Ti(III) complex [MeNacNacTi(Cl){η2-P-PtBu2}]-[Li(12-crown-4)2]+ (2), and via 2e- reduction process to afford new ionic complex [{ArNC(Me)CHC(Me)}Ti═NAr{η1-P(SiMe3)-PtBu2}]-[Li(12-crown-4)2]+ (3). Quite differently, the complex [MeNacNacTi(Cl){η2-P(SiMe3)-PtBu2}] reacts with Ph2PLi in THF, unexpectedly yielding two new, four-coordinate Ti(IV) imido complexes 4a [{ArNC(Me)═CHC(H)(Me)-P(PtBu2)}Ti═NAr(Cl)]-[Li(12-crown-4)2]+·(toluene)2 and 4b [{ArNC(CH2)CH═C(Me)-P(PtBu2)}Ti═NAr(Cl)]-[Li(12-crown-4)2]+·(Et2O). Complex 2 dissolved in THF converts to 4a and 4b. 1, 2, 3, 4a, and 4b were characterized by X-ray diffraction. 1, 4a, and 4b were also fully characterized by multinuclear NMR spectroscopy.
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Affiliation(s)
- A Ziółkowska
- Department of Inorganic Chemistry, Chemical Faculty, Gdansk University of Technology, 11/12 Gabriela Narutowicza Str., 80-233 Gdansk, Poland
| | - N Szynkiewicz
- Department of Inorganic Chemistry, Chemical Faculty, Gdansk University of Technology, 11/12 Gabriela Narutowicza Str., 80-233 Gdansk, Poland
| | - J Pikies
- Department of Inorganic Chemistry, Chemical Faculty, Gdansk University of Technology, 11/12 Gabriela Narutowicza Str., 80-233 Gdansk, Poland
| | - Ł Ponikiewski
- Department of Inorganic Chemistry, Chemical Faculty, Gdansk University of Technology, 11/12 Gabriela Narutowicza Str., 80-233 Gdansk, Poland
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32
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Beaumier EP, Ott AA, Wen X, Davis-Gilbert ZW, Wheeler TA, Topczewski JJ, Goodpaster JD, Tonks IA. Ti-catalyzed ring-opening oxidative amination of methylenecyclopropanes with diazenes. Chem Sci 2020; 11:7204-7209. [PMID: 34123005 PMCID: PMC8159277 DOI: 10.1039/d0sc01998d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 06/20/2020] [Indexed: 12/22/2022] Open
Abstract
The ring-opening oxidative amination of methylenecyclopropanes (MCPs) with diazenes catalyzed by py3TiCl2(NR) complexes is reported. This reaction selectively generates branched α-methylene imines as opposed to linear α,β-unsaturated imines, which are difficult to access via other methods. Products can be isolated as the imine or hydrolyzed to the corresponding ketone in good yields. Mechanistic investigation via density functional theory suggests that the regioselectivity of these products results from a Curtin-Hammett kinetic scenario, where reversible β-carbon elimination of a spirocyclic [2 + 2] azatitanacyclobutene intermediate is followed by selectivity-determining β-hydrogen elimination of the resulting metallacycle. Further functionalizations of these branched α-methylene imine products are explored, demonstrating their utility as building blocks.
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Affiliation(s)
- Evan P Beaumier
- Department of Chemistry, University of Minnesota - Twin Cities 207 Pleasant St SE Minneapolis MN 55455 USA
| | - Amy A Ott
- Department of Chemistry, University of Minnesota - Twin Cities 207 Pleasant St SE Minneapolis MN 55455 USA
| | - Xuelan Wen
- Department of Chemistry, University of Minnesota - Twin Cities 207 Pleasant St SE Minneapolis MN 55455 USA
| | - Zachary W Davis-Gilbert
- Department of Chemistry, University of Minnesota - Twin Cities 207 Pleasant St SE Minneapolis MN 55455 USA
| | - T Alexander Wheeler
- Department of Chemistry, University of Minnesota - Twin Cities 207 Pleasant St SE Minneapolis MN 55455 USA
| | - Joseph J Topczewski
- Department of Chemistry, University of Minnesota - Twin Cities 207 Pleasant St SE Minneapolis MN 55455 USA
| | - Jason D Goodpaster
- Department of Chemistry, University of Minnesota - Twin Cities 207 Pleasant St SE Minneapolis MN 55455 USA
| | - Ian A Tonks
- Department of Chemistry, University of Minnesota - Twin Cities 207 Pleasant St SE Minneapolis MN 55455 USA
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33
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Beaumier EP, Gordon CP, Harkins RP, McGreal ME, Wen X, Copéret C, Goodpaster JD, Tonks IA. Cp 2Ti(κ 2-tBuNCN tBu): A Complex with an Unusual κ 2 Coordination Mode of a Heterocumulene Featuring a Free Carbene. J Am Chem Soc 2020; 142:8006-8018. [PMID: 32240590 PMCID: PMC7201867 DOI: 10.1021/jacs.0c02487] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Although there are myriad binding modes of heterocumulenes to metal centers, the monometallic κ2-ECE (E = O, S, NR) coordination mode has not been reported. Herein, the synthesis, isolation, and physical characterization of Cp2Ti(κ2-tBuNCNtBu) (3) (Cp = cyclopentadienyl, tBu = tert-butyl), a strained 4-membered metallacycle bearing a free carbene, is described. Computational (DFT, CASSCF, QT-AIM, ELF) and solid-state CP-MAS 13C NMR spectroscopic analysis indicate that 3 is best described as a free carbene with partial Ti-Cβ bonding that results from Ti-N π-bonding mixing with N-C-N σ-bonding of the bent N-C-N framework. Reactivity studies of 3 corroborate its carbene-like nature: protonation with [LutH]I results in the formation of a Ti-formamidinate (4), while oxidation with S8 yields a Ti-thioureate (5). Additionally, a related bridged dititanamidocarbene, (Cp2Ti)2(μ-η1,η1-CyNCNCy) (10) (Cy = cyclohexyl) is reported. Taken together, this work suggests that the 2-electron reduction of heterocumulene moieties can allow access to unusual free carbene coordination geometries given the proper stabilizing coordination environment from the reducing transition metal fragment.
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Affiliation(s)
- Evan P. Beaumier
- Department of Chemistry, University of Minnesota – Twin Cities, 207 Pleasant St SE, Minneapolis MN 55455
| | - Christopher P. Gordon
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5, 8093 Zürich, Switzerland
| | - Robin P. Harkins
- Department of Chemistry, University of Minnesota – Twin Cities, 207 Pleasant St SE, Minneapolis MN 55455
| | - Meghan E. McGreal
- Department of Chemistry, University of Minnesota – Twin Cities, 207 Pleasant St SE, Minneapolis MN 55455
| | - Xuelan Wen
- Department of Chemistry, University of Minnesota – Twin Cities, 207 Pleasant St SE, Minneapolis MN 55455
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5, 8093 Zürich, Switzerland
| | - Jason D. Goodpaster
- Department of Chemistry, University of Minnesota – Twin Cities, 207 Pleasant St SE, Minneapolis MN 55455
| | - Ian A. Tonks
- Department of Chemistry, University of Minnesota – Twin Cities, 207 Pleasant St SE, Minneapolis MN 55455
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34
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Kawakita K, Kakiuchi Y, Tsurugi H, Mashima K, Parker BF, Arnold J, Tonks IA. Reactivity of terminal imido complexes of group 4-6 metals: stoichiometric and catalytic reactions involving cycloaddition with unsaturated organic molecules. Coord Chem Rev 2020; 407:213118. [PMID: 32863399 PMCID: PMC7453927 DOI: 10.1016/j.ccr.2019.213118] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Imido complexes of early transition metals are key intermediates in the synthesis of many nitrogen-containing organic compounds. The metal-nitrogen double bond of the imido moiety undergoes [2+2] cycloaddition reactions with various unsaturated organic molecules to form new nitrogen-carbon and nitrogen-heteroatom bonds. This review article focuses on reactivity of the terminal imido complexes of Group 4-6 metals, summarizing their stoichiometric reactions and catalytic applications for a variety of reactions including alkyne hydroamination, alkyne carboamination, pyrrole formation, imine metathesis, and condensation reactions of carbonyl compounds with isocyanates.
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Affiliation(s)
- Kento Kawakita
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Yuya Kakiuchi
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Hayato Tsurugi
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Kazushi Mashima
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Bernard F. Parker
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - John Arnold
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Ian A. Tonks
- Department of Chemistry, University of Minnesota—Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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35
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Li Z, Chen X, Liu LL, Scharnhölz MT, Grützmacher H. N‐Heterocyclic Carbene Stabilized Dicarbondiphosphides: Strong Neutral Four‐Membered Heterocyclic 6π‐Electron Donors. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201914015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Zhongshu Li
- Lehn Institute of Functional Materials (LIFM)School of ChemistrySun Yat-Sen University 510275 Guangzhou China
- State Key Laboratory of Elemento-Organic ChemistryNankai University 30071 Tianjin China
| | - Xiaodan Chen
- College of Chemistry and Materials ScienceJinan University 510632 Guangzhou China
| | - Liu Leo Liu
- Department of ChemistryUniversity of Toronto 80 St. George Street Toronto M5S3H60 Canada
| | - Moritz Theodor Scharnhölz
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir-Prelog-Weg 1 8093 Zürich Switzerland
| | - Hansjörg Grützmacher
- Lehn Institute of Functional Materials (LIFM)School of ChemistrySun Yat-Sen University 510275 Guangzhou China
- State Key Laboratory of Elemento-Organic ChemistryNankai University 30071 Tianjin China
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir-Prelog-Weg 1 8093 Zürich Switzerland
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36
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Pearce AJ, Harkins RP, Reiner BR, Wotal AC, Dunscomb RJ, Tonks IA. Multicomponent Pyrazole Synthesis from Alkynes, Nitriles, and Titanium Imido Complexes via Oxidatively Induced N-N Bond Coupling. J Am Chem Soc 2020; 142:4390-4399. [PMID: 32043879 PMCID: PMC7201868 DOI: 10.1021/jacs.9b13173] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Pyrazoles are an important class of heterocycles found in a wide range of bioactive compounds and pharmaceuticals. Pyrazole synthesis often requires hydrazine or related reagents where an intact N-N bond is conservatively installed into a pyrazole precursor fragment. Herein, we report the multicomponent oxidative coupling of alkynes, nitriles, and Ti imido complexes for the synthesis of multisubstituted pyrazoles. This modular method avoids potentially hazardous reagents like hydrazine, instead forming the N-N bond in the final step via oxidation-induced coupling on Ti. The mechanism of this transformation has been studied in-depth through stoichiometric reactions of the key diazatitanacyclohexadiene intermediate, which can be accessed via multicomponent coupling of Ti imidos with nitriles and alkynes, ring opening of 2-imino-2H-azirines, or direct metalation of 4-azadiene-1-amine derivatives. The critical transformation in this reaction is the 2-electron oxidation-induced N-N coupling on Ti. This is a rare example of formal N-N coupling on a metal center, which likely occurs through an electrocyclic mechanism analogous to a Nazarov cyclization. Conveniently, these 2-electron-oxidized diazatitanacyclohexadiene intermediates can be accessed via disproportionation of the 1-electron-oxidized species, which allows utilization of weak oxidants such as TEMPO.
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Affiliation(s)
- Adam J Pearce
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Robin P Harkins
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Benjamin R Reiner
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Alexander C Wotal
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Rachel J Dunscomb
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Ian A Tonks
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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37
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Gómez-Torres A, Aguilar-Calderón JR, Saucedo C, Jordan A, Metta-Magaña A, Pinter B, Fortier S. Reversible oxidative-addition and reductive-elimination of thiophene from a titanium complex and its thermally-induced hydrodesulphurization chemistry. Chem Commun (Camb) 2020; 56:1545-1548. [PMID: 31922152 DOI: 10.1039/c9cc09267f] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The masked Ti(ii) synthon (Ketguan)(η6-ImDippN)Ti (1) oxidatively adds across thiophene to give ring-opened (Ketguan)(ImDippN)Ti[κ2-S(CH)3CH] (2). Complex 2 is photosensitive, and upon exposure to light, reductively eliminates thiophene to regenerate 1 - a rare example of early-metal mediated oxidative-addition/reductive-elimination chemistry. DFT calculations indicate strong titanium π-backdonation to the thiophene π*-orbitals leads to the observed thiophene ring opening across titanium, while a proposed photoinduced LMCT promotes the reverse thiophene elimination from 2. Finally, pressurizing solutions of 2 with H2 (150 psi) at 80 °C leads to the hydrodesulphurization of thiophene to give the Ti(iv) sulphide (Ketguan)(ImDippN)Ti(S) (3) and butane.
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Affiliation(s)
- Alejandra Gómez-Torres
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, TX 79968, USA.
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38
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Li Z, Chen X, Liu LL, Scharnhölz MT, Grützmacher H. N‐Heterocyclic Carbene Stabilized Dicarbondiphosphides: Strong Neutral Four‐Membered Heterocyclic 6π‐Electron Donors. Angew Chem Int Ed Engl 2020; 59:4288-4293. [DOI: 10.1002/anie.201914015] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 12/14/2019] [Indexed: 12/14/2022]
Affiliation(s)
- Zhongshu Li
- Lehn Institute of Functional Materials (LIFM)School of ChemistrySun Yat-Sen University 510275 Guangzhou China
- State Key Laboratory of Elemento-Organic ChemistryNankai University 30071 Tianjin China
| | - Xiaodan Chen
- College of Chemistry and Materials ScienceJinan University 510632 Guangzhou China
| | - Liu Leo Liu
- Department of ChemistryUniversity of Toronto 80 St. George Street Toronto M5S3H60 Canada
| | - Moritz Theodor Scharnhölz
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir-Prelog-Weg 1 8093 Zürich Switzerland
| | - Hansjörg Grützmacher
- Lehn Institute of Functional Materials (LIFM)School of ChemistrySun Yat-Sen University 510275 Guangzhou China
- State Key Laboratory of Elemento-Organic ChemistryNankai University 30071 Tianjin China
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir-Prelog-Weg 1 8093 Zürich Switzerland
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39
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Zhizhko PA, Pichugov AV, Bushkov NS, Rumyantsev AV, Utegenov KI, Talanova VN, Strelkova TV, Lebedev D, Mance D, Zarubin DN. Catalytic Imido-Transfer Reactions of Well-Defined Silica-Supported Titanium Imido Complexes Prepared via Surface Organometallic Chemistry. Organometallics 2020. [DOI: 10.1021/acs.organomet.9b00779] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Pavel A. Zhizhko
- A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119991 Moscow, Russia
| | - Andrey V. Pichugov
- A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119991 Moscow, Russia
- Higher Chemical College, D. Mendeleev University of Chemical Technology of Russia, Miusskaya sq., 9, 125047 Moscow, Russia
| | - Nikolai S. Bushkov
- A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119991 Moscow, Russia
- Department of Chemistry, Moscow State University, Vorob’evy Gory, 1, 119991 Moscow, Russia
| | - Andrey V. Rumyantsev
- A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119991 Moscow, Russia
- Department of Chemistry, Moscow State University, Vorob’evy Gory, 1, 119991 Moscow, Russia
| | - Kamil I. Utegenov
- A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119991 Moscow, Russia
| | - Valeria N. Talanova
- A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119991 Moscow, Russia
| | - Tatyana V. Strelkova
- A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119991 Moscow, Russia
| | - Dmitry Lebedev
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog Weg, 1−5, CH-8093 Zürich, Switzerland
| | - Deni Mance
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog Weg, 1−5, CH-8093 Zürich, Switzerland
| | - Dmitry N. Zarubin
- A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119991 Moscow, Russia
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40
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Zhou L, An XD, Yang S, Li XJ, Shao CL, Liu Q, Xiao J. Organocatalytic Cascade β-Functionalization/Aromatization of Pyrrolidines via Double Hydride Transfer. Org Lett 2020; 22:776-780. [DOI: 10.1021/acs.orglett.9b03918] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Lan Zhou
- School of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, Qingdao 266109, China
| | - Xiao-De An
- School of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, Qingdao 266109, China
| | - Shuo Yang
- School of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, Qingdao 266109, China
| | - Xian-Jiang Li
- Shandong Kangqiao Biotechnology Co., Ltd., Binzhou 256500, China
| | - Chang-Lun Shao
- Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - Qing Liu
- College of Chemical and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590, China
| | - Jian Xiao
- Shandong Province Key Laboratory of Applied Mycology, School of Chemistry and Pharmaceutical Sciences, School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao 266109, China
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41
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Ploeger ML, Darù A, Harvey JN, Hu X. Reductive Cleavage of Azoarene as a Key Step in Nickel-Catalyzed Amidation of Esters with Nitroarenes. ACS Catal 2020. [DOI: 10.1021/acscatal.9b05049] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Marten L. Ploeger
- Laboratory of Inorganic Synthesis and Catalysis, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), ISIC-LSCI, BCH 3305, Lausanne 1015, Switzerland
| | - Andrea Darù
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - Jeremy N. Harvey
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - Xile Hu
- Laboratory of Inorganic Synthesis and Catalysis, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), ISIC-LSCI, BCH 3305, Lausanne 1015, Switzerland
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42
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Kurup SS, Staples RJ, Lord RL, Groysman S. Synthesis of Chromium(II) Complexes with Chelating Bis(alkoxide) Ligand and Their Reactions with Organoazides and Diazoalkanes. MOLECULES (BASEL, SWITZERLAND) 2020; 25:molecules25020273. [PMID: 31936557 PMCID: PMC7024303 DOI: 10.3390/molecules25020273] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/03/2020] [Accepted: 01/07/2020] [Indexed: 12/22/2022]
Abstract
Synthesis of new chromium(II) complexes with chelating bis(alkoxide) ligand [OO]Ph (H2[OO]Ph = [1,1′:4′,1′’-terphenyl]-2,2′’-diylbis(diphenylmethanol)) and their subsequent reactivity in the context of catalytic production of carbodiimides from azides and isocyanides are described. Two different Cr(II) complexes are obtained, as a function of the crystallization solvent: mononuclear Cr[OO]Ph(THF)2 (in toluene/THF, THF = tetrahydrofuran) and dinuclear Cr2([OO]Ph)2 (in CH2Cl2/THF). The electronic structure and bonding in Cr[OO]Ph(THF)2 were probed by density functional theory calculations. Isolated Cr2([OO]Ph)2 undergoes facile reaction with 4-MeC6H4N3, 4-MeOC6H4N3, or 3,5-Me2C6H3N3 to yield diamagnetic Cr(VI) bis(imido) complexes; a structure of Cr[OO]Ph(N(4-MeC6H4))2 was confirmed by X-ray crystallography. The reaction of Cr2([OO]Ph)2 with bulkier azides N3R (MesN3, AdN3) forms paramagnetic products, formulated as Cr[OO]Ph(NR). The attempted formation of a Cr–alkylidene complex (using N2CPh2) instead forms chromium(VI) bis(diphenylmethylenehydrazido) complex Cr[OO]Ph(NNCPh2)2. Catalytic formation of carbodiimides was investigated for the azide/isocyanide mixtures containing various aryl azides and isocyanides. The formation of carbodiimides was found to depend on the nature of organoazide: whereas bulky mesitylazide led to the formation of carbodiimides with all isocyanides, no carbodiimide formation was observed for 3,5-dimethylphenylazide or 4-methylphenylazide. Treatment of Cr2([OO]Ph)2 or H2[OO]Ph with NO+ leads to the formation of [1,2-b]-dihydroindenofluorene, likely obtained via carbocation-mediated cyclization of the ligand.
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Affiliation(s)
- Sudheer S. Kurup
- Department of Chemistry, Wayne State University, 5101 Cass Ave., Detroit, MI 48202, USA;
| | - Richard J. Staples
- Department of Chemistry, Michigan State University, 578 S Shaw Ln, East Lansing, MI 48824, USA;
| | - Richard L. Lord
- Department of Chemistry, Grand Valley State University, 1 Campus Dr, Allendale, MI 49401, USA
- Correspondence: (R.L.L.); (S.G.)
| | - Stanislav Groysman
- Department of Chemistry, Wayne State University, 5101 Cass Ave., Detroit, MI 48202, USA;
- Correspondence: (R.L.L.); (S.G.)
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43
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Liang W, Nakajima K, Nishibayashi Y. Synthesis of 1,2,4-azadiphosphole derivatives based on vanadium-catalyzed [2+2+1] cycloaddition reactions of azobenzenes with phosphaalkynes. RSC Adv 2020; 10:12730-12733. [PMID: 35492129 PMCID: PMC9051379 DOI: 10.1039/d0ra02503h] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 03/19/2020] [Indexed: 11/21/2022] Open
Abstract
A new synthetic method is described to construct 1,2,4-azadiphosphole derivatives based on vanadium-catalyzed [2+2+1] cycloaddition reactions. Reactions of azobenzenes as nitrogen sources with phosphaalkynes as phosphorous counterparts in the presence of VCl2(thf)2 as a catalyst afford the corresponding 1,2,4-azadiphospholes. Vanadium-catalyzed [2+2+1] cycloaddition reactions opened a new access to phosphorous-heterocycles.![]()
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Affiliation(s)
- Wenbin Liang
- Department of Systems Innovation
- School of Engineering
- The University of Tokyo
- Tokyo 113-8656
- Japan
| | - Kazunari Nakajima
- Frontier Research Center for Energy and Resources
- School of Engineering
- The University of Tokyo
- Tokyo 113-8656
- Japan
| | - Yoshiaki Nishibayashi
- Department of Systems Innovation
- School of Engineering
- The University of Tokyo
- Tokyo 113-8656
- Japan
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44
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Titanium catalyzed synthesis of amines and N-heterocycles. ADVANCES IN ORGANOMETALLIC CHEMISTRY 2020. [DOI: 10.1016/bs.adomc.2020.04.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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45
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Zhou J, Kim H, Liu LL, Cao LL, Stephan DW. An arene-stabilized η5-pentamethylcyclopentadienyl antimony dication acts as a source of Sb+ or Sb3+ cations. Chem Commun (Camb) 2020; 56:12953-12956. [DOI: 10.1039/d0cc02710c] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The dicationic compound [(η5-Cp*)Sb(tol)][B(C6F5)4]2 (1) (tol = toluene), which exhibits strong Lewis acidity, reacts with Lewis bases to provide Sb+ or Sb3+ cations.
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Affiliation(s)
- Jiliang Zhou
- Department of Chemistry
- University of Toronto
- Toronto
- Canada
| | - Hyehwang Kim
- Department of Chemistry
- University of Toronto
- Toronto
- Canada
| | - Liu Leo Liu
- Department of Chemistry
- University of Toronto
- Toronto
- Canada
| | - Levy L. Cao
- Department of Chemistry
- University of Toronto
- Toronto
- Canada
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46
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Manßen M, Schafer LL. Titanium catalysis for the synthesis of fine chemicals – development and trends. Chem Soc Rev 2020; 49:6947-6994. [DOI: 10.1039/d0cs00229a] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Atlas as a Titan(ium) is holding the earth-abundant chemistry world. Titanium is the second most abundant transition metal, is a key player in important industrial processes (e.g. polyethylene) and shows much promise for diverse applications in the future.
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Affiliation(s)
- Manfred Manßen
- The Department of Chemistry
- The University of British Columbia
- Vancouver
- Canada
| | - Laurel L. Schafer
- The Department of Chemistry
- The University of British Columbia
- Vancouver
- Canada
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47
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Beaumier EP, McGreal ME, Pancoast AR, Wilson RH, Moore JT, Graziano BJ, Goodpaster JD, Tonks IA. Carbodiimide Synthesis via Ti-Catalyzed Nitrene Transfer from Diazenes to Isocyanides. ACS Catal 2019; 9:11753-11762. [PMID: 34113477 DOI: 10.1021/acscatal.9b04107] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Simple Ti imido halide complexes such as [Br2Ti(N t Bu)py2]2 are competent catalysts for the synthesis of unsymmetrical carbodiimides via Ti-catalyzed nitrene transfer from diazenes or azides to isocyanides. Both alkyl and aryl isocyanides are compatible with the reaction conditions, although product inhibition with sterically unencumbered substrates sometimes limits the yield when diazenes are employed as the oxidant. The reaction mechanism has been investigated both experimentally and computationally, wherein a key feature is that the product release is triggered by electron transfer from an η 2-carbodiimide to a Ti-bound azobenzene. This ligand-to-ligand redox buffering obviates the need for high-energy formally TiII intermediates and provides further evidence that substrate and product "redox noninnocence" can promote unusual Ti redox catalytic transformations.
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Affiliation(s)
- Evan P. Beaumier
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Meghan E. McGreal
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Adam R. Pancoast
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - R. Hunter Wilson
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - James T. Moore
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Brendan J. Graziano
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Jason D. Goodpaster
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Ian A. Tonks
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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48
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Aldrich KE, Kansal D, Odom AL. Catalyst design insights from modelling a titanium-catalyzed multicomponent reaction. Faraday Discuss 2019; 220:208-230. [PMID: 31528974 DOI: 10.1039/c9fd00033j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High oxidation state transition metal catalysis touches our daily lives through bulk chemical production, e.g. olefin polymerization, and through specialty chemical reactions common in organic synthesis, e.g. the Sharpless asymmetric epoxidation and olefin dihydroxylation. Our group has been expanding the reaction chemistry of titanium(iv) to produce a host of nitrogen-based heterocycles via multicomponent coupling reactions. One such multicomponent coupling reaction discovered in our laboratory is iminoamination, involving an amine, an alkyne, and an isonitrile. However, the experimental modeling of high oxidation state reactions lags far behind that of low oxidation state systems, where a great deal is known about ligands, their donor properties and how their structures affect catalysis. As a result, we have developed an experimental method for determining the donor abilities of anionic ligands on high oxidation state systems, which is based on the chromium(vi) nitride system NCr(NiPr2)2X, where X = the ligand being interrogated. The parameters obtained are simply called ligand donor parameters (LDP). In this contribution, a detailed optimization of the Ti(NMe2)2(dpm)-catalyzed iminoamination reaction was carried out, where dpm = 5,5-dimethyldipyrrolylmethane. During the course of these studies, dimeric {Ti(μ-N-tolyl)(dpm)}2 was isolated, which is proposed as the resting state of the catalyst. To destabilize this resting state, a more electron-rich bis(aryloxide) catalyst system was investigated. The more electron-rich system is somewhat more active for iminoamination under some conditions; however, the catalyst is prone to disproportionation. A study of heteroleptic titanium complexes revealed that the disproportionation equilibrium constant can be effectively modeled as a function of the square of the difference in LDP between the ligands, (ΔLDP)2. Using this methodology, one can estimate the stability of titanium complexes toward disproportionation.
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Affiliation(s)
- Kelly E Aldrich
- Department of Chemistry, Michigan State University, 578 S. Shaw Ln, East Lansing, MI 48824, USA.
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49
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Kawakita K, Kakiuchi Y, Beaumier EP, Tonks IA, Tsurugi H, Mashima K. Synthesis of Pyridylimido Complexes of Tantalum and Niobium by Reductive Cleavage of the N═N Bond of 2,2'-Azopyridine: Precursors for Early-Late Heterobimetallic Complexes. Inorg Chem 2019; 58:15155-15165. [PMID: 31553585 PMCID: PMC7017918 DOI: 10.1021/acs.inorgchem.9b02043] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the syntheses of 2-pyridylimido complexes of tantalum and niobium by N═N bond cleavage of 2,2'-azopyridine. Reaction of MCl5 (M = Ta and Nb) with 2,2'-azopyridine in the presence of 0.5 equiv of 1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene (abbreviated Si-Me-CHD) afforded a dark red solution (for Ta) and a dark blue solution (for Nb) with some insoluble precipitates. After removing the solids, another 0.5 equiv of Si-Me-CHD was added to each solution, giving [M(═Npy)Cl3]n (1a: M = Ta; 1b: M = Nb) through reductive cleavage of the N═N bond of 2,2'-azopyridine. The initial products of the above reactions were determined to be 2,2'-azopyridine-bridged dinuclear complexes, [(MCl4)2(μ-pyNNpy)] (2a: M = Ta; 2b: M = Nb), which were isolated by treating MCl5 with 2,2'-azopyridine and Si-Me-CHD in a 2:1:1 molar ratio. In 2a and 2b, the N═N bond was reduced to a single bond via two-electron reduction. Further reduction of complexes 2a and 2b with 1 equiv of Si-Me-CHD afforded complexes 1a and 1b. An anionic doubly μ-imido-bridged ditantalum complex, [nBu4N][Ta2(μ-Npy)2Cl7] (3a), was generated upon addition of nBu4NCl to complex 1a, while addition of nBu4NCl to niobium complex 1b gave a polymeric terminal imido complex, [nBu4N]n/2[{Nb(═Npy)Cl3}2(μ-Cl)]n/2 (3b). Complexations of 1a and 1b with 1 equiv of 2,2'-bipyridine resulted in the formation of mononuclear 2-pyridylimido complexes, M(═Npy)Cl3(bipy) (4a: M = Ta; 4b: M = Nb), whose main structural feature is intramolecular hydrogen bonding between the ortho hydrogen atom of 2,2'-bipyridine and the nitrogen atom of the pyridyl group on the imido ligand. Isolated 2-pyridylimido complexes 4a and 4b reacted with [RhCl(cod)]2 to produce the corresponding early-late heterobimetallic complexes, (bipy)MCl3(μ-Npy)RhCl(cod) (5a: M = Ta; 5b: M = Nb).
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Affiliation(s)
- Kento Kawakita
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Yuya Kakiuchi
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Evan P. Beaumier
- Department of Chemistry, University of Minnesota–Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Ian A. Tonks
- Department of Chemistry, University of Minnesota–Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Hayato Tsurugi
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Kazushi Mashima
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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50
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Laudenschlager JE, Combee LA, Hilinski MK. Intermolecular scandium triflate-promoted nitrene-transfer [5 + 1] cycloadditions of vinylcyclopropanes. Org Biomol Chem 2019; 17:9413-9417. [PMID: 31641723 DOI: 10.1039/c9ob01858a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Sc(OTf)3-promoted [5 + 1] cycloaddition of vinylcyclopropanes with PhINTs is reported, enabling the regioselective preparation of a range of 1,2,3,6-tetrahydropyridine scaffolds under mild conditions. This represents the second example of a [5 + 1] nitrene-transfer cycloaddition and exhibits complementary substrate scope to the antecedent work, expanding the range of N-heterocycles accessible via this strategy.
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Affiliation(s)
- Julie E Laudenschlager
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904-4319, USA.
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