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Thoben N, Kaper T, de Graaff S, Gerhards L, Schmidtmann M, Klüner T, Beckhaus R, Doye S. Density Functional Theory Calculations for Multiple Conformers Explaining the Regio- and Stereoselectivity of Ti-Catalyzed Hydroaminoalkylation Reactions. Chemphyschem 2023; 24:e202300370. [PMID: 37326019 DOI: 10.1002/cphc.202300370] [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] [Received: 05/31/2023] [Revised: 06/16/2023] [Accepted: 06/16/2023] [Indexed: 06/17/2023]
Abstract
Hybrid Density Functional Theory (DFT) calculations for multiple conformers of the insertion reactions of a methylenecyclopropane into the Ti-C bond of two differently α-substituted titanaaziridines explain the experimentally observed differences in regioselectivity between catalytic hydroaminoalkylation reactions of methylenecyclopropanes with α-phenyl-substituted secondary amines and corresponding stoichiometric reactions of a methylenecyclopropane with titanaaziridines, which can only be achieved with α-unsubstituted titanaaziridines. In addition, the lack of reactivity of α-phenyl-substituted titanaaziridines as well as the diastereoselectivity of the catalytic and stoichiometric reactions can be understood.
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Affiliation(s)
- Niklas Thoben
- Institut für Chemie, Universität Oldenburg, Carl-von-Ossietzky-Strasse 9-11, 26129, Oldenburg, Germany
| | - Tobias Kaper
- Institut für Chemie, Universität Oldenburg, Carl-von-Ossietzky-Strasse 9-11, 26129, Oldenburg, Germany
| | - Simon de Graaff
- Institut für Chemie, Universität Oldenburg, Carl-von-Ossietzky-Strasse 9-11, 26129, Oldenburg, Germany
| | - Luca Gerhards
- Institut für Physik, Universität Oldenburg, Carl-von-Ossietzky-Strasse 9-11, 26129, Oldenburg, Germany
| | - Marc Schmidtmann
- Institut für Chemie, Universität Oldenburg, Carl-von-Ossietzky-Strasse 9-11, 26129, Oldenburg, Germany
| | - Thorsten Klüner
- Institut für Chemie, Universität Oldenburg, Carl-von-Ossietzky-Strasse 9-11, 26129, Oldenburg, Germany
| | - Rüdiger Beckhaus
- Institut für Chemie, Universität Oldenburg, Carl-von-Ossietzky-Strasse 9-11, 26129, Oldenburg, Germany
| | - Sven Doye
- Institut für Chemie, Universität Oldenburg, Carl-von-Ossietzky-Strasse 9-11, 26129, Oldenburg, Germany
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WANG W, Zou PS, PANG L, Pan C, Mo DL, SU GF. Recent Advances on the Synthesis of 2,3-Fused Quinazolinones. Org Biomol Chem 2022; 20:6293-6313. [DOI: 10.1039/d2ob00778a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
As one of the most important structural units in pharmaceuticals and medicinal chemistry, quinazolinone and its derivatives exhibit a wide range of biological and pharmacological activities, including anti-inflammatory, antitubercular, antiviral,...
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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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Wannipurage D, Kurup SS, Groysman S. Heterocoupling of Different Aryl Nitrenes to Produce Asymmetric Azoarenes Using Iron–Alkoxide Catalysis and Investigation of the Cis–Trans Isomerism of Selected Bulky Asymmetric Azoarenes. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00490] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Duleeka Wannipurage
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Sudheer S. Kurup
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Stanislav Groysman
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
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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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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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Pearce AJ, Cheng Y, Dunscomb RJ, Tonks IA. Generation of Masked Ti II Intermediates from Ti IV Amides via β-H Abstraction or Alkyne Deprotonation: An Example of Ti-Catalyzed Nitrene-Coupled Transfer Hydrogenation. Organometallics 2020; 39:3771-3774. [PMID: 34321708 DOI: 10.1021/acs.organomet.0c00577] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Simple Ti amide complexes are shown to act as sources for masked TiII intermediates via several pathways, as demonstrated through the investigation of a unique Ti-catalyzed nitrene-coupled transfer hydrogenation of 3-hexyne. This reaction proceeds through reduction of azobenzene by a masked TiII catalyst, wherein both amines and 3-hexyne can serve as the hydrogen source/reductant for Ti by forming putative titanaziridines via β-H abstraction or putative titanacyclopentynes via protonolysis, respectively.
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Affiliation(s)
- Adam J Pearce
- Department of Chemistry, University of Minnesota-Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Yukun Cheng
- Department of Chemistry, University of Minnesota-Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Rachel J Dunscomb
- 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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