1
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Sinhababu S, Singh RP, Radzhabov MR, Kumawat J, Ess DH, Mankad NP. Coordination-induced O-H/N-H bond weakening by a redox non-innocent, aluminum-containing radical. Nat Commun 2024; 15:1315. [PMID: 38351122 PMCID: PMC10864259 DOI: 10.1038/s41467-024-45721-1] [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: 10/11/2023] [Accepted: 02/01/2024] [Indexed: 02/16/2024] Open
Abstract
Several renewable energy schemes aim to use the chemical bonds in abundant molecules like water and ammonia as energy reservoirs. Because the O-H and N-H bonds are quite strong (>100 kcal/mol), it is necessary to identify substances that dramatically weaken these bonds to facilitate proton-coupled electron transfer processes required for energy conversion. Usually this is accomplished through coordination-induced bond weakening by redox-active metals. However, coordination-induced bond weakening is difficult with earth's most abundant metal, aluminum, because of its redox inertness under mild conditions. Here, we report a system that uses aluminum with a redox non-innocent ligand to achieve significant levels of coordination-induced bond weakening of O-H and N-H bonds. The multisite proton-coupled electron transfer manifold described here points to redox non-innocent ligands as a design element to open coordination-induced bond weakening chemistry to more elements in the periodic table.
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Affiliation(s)
- Soumen Sinhababu
- Department of Chemistry, University of Illinois Chicago, Chicago, IL, 60607, USA
| | | | - Maxim R Radzhabov
- Department of Chemistry, University of Illinois Chicago, Chicago, IL, 60607, USA
| | - Jugal Kumawat
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, 84604, UT, USA
| | - Daniel H Ess
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, 84604, UT, USA
| | - Neal P Mankad
- Department of Chemistry, University of Illinois Chicago, Chicago, IL, 60607, USA.
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2
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Oloyede UN, Flowers RA. Coordination-induced bond weakening and small molecule activation by low-valent titanium complexes. Dalton Trans 2024; 53:2413-2441. [PMID: 38224159 DOI: 10.1039/d3dt03454b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2024]
Abstract
Bond activation of small molecules through coordination to low valent metal complexes in M⋯X-H type interactions (where X = O, N, B, Si, etc.) leads to the formation of unusually weak X-H bonds and provides a powerful approach for the synthesis of target compounds under very mild conditions. Coordination of small molecules like water, amides, silanes, boranes, and dinitrogen to Ti(III) or Ti(II) complexes results in the synergetic redistribution of electrons between the metal orbitals and the ligand orbitals which weakens and enables the facile cleavage of the X-H or N-N bonds of the ligands. This review presents an overview of coordination-induced bond activation of small molecules by low valent titanium complexes. In particular, the applications of low valent titanium-induced bond weakening in nitrogen fixation are presented. The review concludes with potential future directions for work in this area including low-valent Ti-based PCET systems, photocatalytic nitrogen reduction, and approaches to tailoring complexes for optimal bond activation.
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Affiliation(s)
| | - Robert A Flowers
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
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3
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Chatgilialoglu C, Barata-Vallejo S, Gimisis T. Radical Reactions in Organic Synthesis: Exploring in-, on-, and with-Water Methods. Molecules 2024; 29:569. [PMID: 38338314 PMCID: PMC10856544 DOI: 10.3390/molecules29030569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/18/2024] [Accepted: 01/19/2024] [Indexed: 02/12/2024] Open
Abstract
Radical reactions in water or aqueous media are important for organic synthesis, realizing high-yielding processes under non-toxic and environmentally friendly conditions. This overview includes (i) a general introduction to organic chemistry in water and aqueous media, (ii) synthetic approaches in, on, and with water as well as in heterogeneous phases, (iii) reactions of carbon-centered radicals with water (or deuterium oxide) activated through coordination with various Lewis acids, (iv) photocatalysis in water and aqueous media, and (v) synthetic applications bioinspired by naturally occurring processes. A wide range of chemical processes and synthetic strategies under different experimental conditions have been reviewed that lead to important functional group translocation and transformation reactions, leading to the preparation of complex molecules. These results reveal how water as a solvent/medium/reagent in radical chemistry has matured over the last two decades, with further discoveries anticipated in the near future.
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Affiliation(s)
- Chryssostomos Chatgilialoglu
- Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche, 40129 Bologna, Italy
- Center of Advanced Technologies, Adam Mickiewicz University, 61-712 Poznan, Poland
| | - Sebastian Barata-Vallejo
- Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche, 40129 Bologna, Italy
- Facultad de Farmacia y Bioquímica, Departamento de Ciencias Químicas, Universidad de Buenos Aires, Junin 954, Buenos Aires CP 1113, Argentina
| | - Thanasis Gimisis
- Department of Chemistry, National and Kapodistrian University of Athens, 15771 Athens, Greece
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4
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Zhang J, Mück-Lichtenfeld C, Studer A. Photocatalytic phosphine-mediated water activation for radical hydrogenation. Nature 2023; 619:506-513. [PMID: 37380779 PMCID: PMC10356606 DOI: 10.1038/s41586-023-06141-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 04/27/2023] [Indexed: 06/30/2023]
Abstract
The chemical activation of water would allow this earth-abundant resource to be transferred into value-added compounds, and is a topic of keen interest in energy research1,2. Here, we demonstrate water activation with a photocatalytic phosphine-mediated radical process under mild conditions. This reaction generates a metal-free PR3-H2O radical cation intermediate, in which both hydrogen atoms are used in the subsequent chemical transformation through sequential heterolytic (H+) and homolytic (H•) cleavage of the two O-H bonds. The PR3-OH radical intermediate provides an ideal platform that mimics the reactivity of a 'free' hydrogen atom, and which can be directly transferred to closed-shell π systems, such as activated alkenes, unactivated alkenes, naphthalenes and quinoline derivatives. The resulting H adduct C radicals are eventually reduced by a thiol co-catalyst, leading to overall transfer hydrogenation of the π system, with the two H atoms of water ending up in the product. The thermodynamic driving force is the strong P=O bond formed in the phosphine oxide by-product. Experimental mechanistic studies and density functional theory calculations support the hydrogen atom transfer of the PR3-OH intermediate as a key step in the radical hydrogenation process.
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Affiliation(s)
- Jingjing Zhang
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Münster, Germany
| | - Christian Mück-Lichtenfeld
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Münster, Germany
- Center for Multiscale Theory and Computation, Westfälische Wilhelms-Universität, Münster, Germany
| | - Armido Studer
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Münster, Germany.
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5
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Lin Q, Tong W, Shu XZ, Chen Y. Ti-Catalyzed Dehydroxylation of Tertiary Alcohols. Org Lett 2022; 24:8459-8464. [DOI: 10.1021/acs.orglett.2c03119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Quan Lin
- School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, People’s Republic of China
- Center for Supramolecular Chemistry and Catalysis and Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, People’s Republic of China
| | - Weiqi Tong
- Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, People’s Republic of China
| | - Xing-Zhong Shu
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University, 222 South Tianshui Road, Lanzhou 730000, People’s Republic of China
| | - Yunrong Chen
- Center for Supramolecular Chemistry and Catalysis and Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, People’s Republic of China
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6
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Beck NB, Bai Z, Brannon JP, Martinez DG, Grödler D, Long BN, Poe TN, Rotermund BM, Albrecht-Schönzart TE, Sperling JM. Two Neptunium(III) Mellitate Coordination Polymers: Completing the Series Np–Cf of Trans-Uranic An(III) Mellitates. Inorg Chem 2022; 61:17730-17737. [DOI: 10.1021/acs.inorgchem.2c02873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Nicholas B. Beck
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Zhuanling Bai
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Jacob P. Brannon
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Daniela Gomez Martinez
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Dennis Grödler
- Department of Chemistry, Institute for Inorganic Chemistry, University of Cologne, Greinstr. 4-6, Cologne 50939, Germany
| | - Brian N. Long
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Todd N. Poe
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Brian M. Rotermund
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | | | - Joseph M. Sperling
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
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7
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Abstract
Coordination-induced bond weakening is a phenomenon wherein ligand X-H bond homolysis occurs in concert with the energetically favorable oxidation of a coordinating metal complex. The coupling of these two processes enables thermodynamically favorable proton-coupled electron transfer reductions to form weak bonds upon formal hydrogen atom transfer to substrates. Moreover, systems utilizing coordination-induced bond weakening have been shown to facilitate the dehydrogenation of feedstock molecules including water, ammonia, and primary alcohols under mild conditions. The formation of exceptionally weak substrate X-H bonds via small molecule homolysis is a powerful strategy in synthesis and has been shown to enable nitrogen fixation under mild conditions. Coordination-induced bond weakening has also been identified as an integral process in biophotosynthesis and has promising applications in renewable chemical fuel storage systems. This review presents a discussion of the advances made in the study of coordination-induced bond weakening to date. Because of the broad range of metal and ligand species implicated in coordination-induced bond weakening, each literature report is discussed individually and ordered by the identity of the low-valent metal. We then offer mechanistic insights into the basis of coordination-induced bond weakening and conclude with a discussion of opportunities for further research into the development and applications of coordination-induced bond weakening systems.
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Affiliation(s)
- Nicholas G Boekell
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Robert A Flowers
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
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8
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Hilche T, Younas SL, Gansäuer A, Streuff J. A Guide to Low‐Valent Titanocene Complexes as Tunable Single‐Electron Transfer Catalysts for Applications in Organic Chemistry. ChemCatChem 2022. [DOI: 10.1002/cctc.202200530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Tobias Hilche
- Rheinische Friedrich-Wilhelms-Universitat Bonn Kekulé-Institut für Organische Chemie und Biochemie Gerhard-Domagk-Str. 1 53121 Bonn GERMANY
| | - Sara L. Younas
- Albert-Ludwigs-Universitat Freiburg Institut für Organische Chemie Albertstr. 21 79104 Freiburg im Breisgau GERMANY
| | - Andreas Gansäuer
- Rheinische Friedrich-Wilhelms-Universitat Bonn Kekulé-Institut für Organische Chemie und Biochemie Gerhard-Domagk-Str. 1 53121 Bonn GERMANY
| | - Jan Streuff
- Uppsala Universitet Department of Chemistry - BMC Husargatan 3 752 37 Uppsala SWEDEN
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9
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Matsunaga K, Endo R, Nagasawa K, Kishida A, Takatori K. Synthesis of Succinonitrile Derivatives by Homocoupling from Cyanohydrin Derivatives with a Low-Valent Titanium Reagent. J Org Chem 2022; 87:3707-3711. [PMID: 35049306 DOI: 10.1021/acs.joc.1c02643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A method is described for synthesizing succinonitrile derivatives bearing alkyl or aryl substituents from cyanohydrin derivatives using low-valent titanium. The active species in this reaction is proposed to be a resonance hybrid of the TiIV nitrile enolate and TiIII alkyl radical.
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Affiliation(s)
- Kazuma Matsunaga
- Graduate School of Pharmaceutical Sciences, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
| | - Ryusei Endo
- Graduate School of Pharmaceutical Sciences, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
| | - Kokoro Nagasawa
- Graduate School of Pharmaceutical Sciences, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
| | - Atsushi Kishida
- Graduate School of Pharmaceutical Sciences, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
| | - Kazuhiko Takatori
- Graduate School of Pharmaceutical Sciences, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
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10
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Ramírez-Solís A, Boekell NG, León-Pimentel CI, Saint-Martin H, Bartulovich CO, Flowers RA. Ammonia Solvation vs Aqueous Solvation of Samarium Diiodide. A Theoretical and Experimental Approach to Understanding Bond Activation Upon Coordination to Sm(II). J Org Chem 2021; 87:1689-1697. [PMID: 34775764 DOI: 10.1021/acs.joc.1c01771] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Coordination-induced desolvation or ligand displacement by cosolvents and additives is a key feature responsible for the reactivity of Sm(II)-based reagent systems. High-affinity proton donor cosolvents such as water and glycols also demonstrate coordination-induced bond weakening of the O-H bond, facilitating reduction of a broad range of substrates. In the present work, the coordination of ammonia to SmI2 was examined using Born-Oppenheimer molecular dynamics simulations and mechanistic studies, and the SmI2-ammonia system is compared to the SmI2-water system. The coordination number and reactivity of the SmI2-ammonia solvent system were found to be similar to those of SmI2-water but exhibited an order of magnitude greater rate of arene reduction by SmI2-ammonia than by SmI2-water at the same concentrations of cosolvent. In addition, upon coordination of ammonia to SmI2, the Sm(II)-ammonia solvate demonstrates one of the largest degrees of N-H bond weakening reported in the literature compared to known low-valent transition metal ammonia complexes.
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Affiliation(s)
- Alejandro Ramírez-Solís
- Depto. de Física, Centro de Investigación en Ciencias-IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos 62209, México
| | - Nicholas G Boekell
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | | | | | - Caroline O Bartulovich
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Robert A Flowers
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
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11
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Younas SL, Streuff J. Kinetic Analysis Uncovers Hidden Autocatalysis and Inhibition Pathways in Titanium(III)-Catalyzed Ketone-Nitrile Couplings. ACS Catal 2021. [DOI: 10.1021/acscatal.1c02870] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Sara L. Younas
- Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Jan Streuff
- Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany
- Department of Chemistry—BMC, Uppsala University, Husargatan 3, 75237 Uppsala, Sweden
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12
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Zhang Z, Stückrath JB, Grimme S, Gansäuer A. Titanocene‐Catalyzed [2+2] Cycloaddition of Bisenones and Comparison with Photoredox Catalysis and Established Methods. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202102739] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Zhenhua Zhang
- Kekulé-Institut für Organische Chemie und Biochemie Universität Bonn Gerhard-Domagk-Strasse 1 53121 Bonn Germany
| | - Julius B. Stückrath
- Mulliken Center for Theoretical Chemistry Institut für Physikalische und Theoretische Chemie Universität Bonn Beringstrasse 4 53115 Bonn Germany
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry Institut für Physikalische und Theoretische Chemie Universität Bonn Beringstrasse 4 53115 Bonn Germany
| | - Andreas Gansäuer
- Kekulé-Institut für Organische Chemie und Biochemie Universität Bonn Gerhard-Domagk-Strasse 1 53121 Bonn Germany
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13
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Zhang Z, Stückrath JB, Grimme S, Gansäuer A. Titanocene-Catalyzed [2+2] Cycloaddition of Bisenones and Comparison with Photoredox Catalysis and Established Methods. Angew Chem Int Ed Engl 2021; 60:14339-14344. [PMID: 33871126 PMCID: PMC8251790 DOI: 10.1002/anie.202102739] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Indexed: 12/17/2022]
Abstract
Cp2 Ti(TFA) is a broadly applicable catalyst for the [2+2] cycloaddition of bisenones by inner-sphere electron transfer. The attractiveness of this mechanism is shown by comparison with outer-sphere ET methods. DFT calculations show that the reaction proceeds through a unique unfavorable 5-exo (the rate-determining step) and a favorable 4-exo cyclization.
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Affiliation(s)
- Zhenhua Zhang
- Kekulé-Institut für Organische Chemie und BiochemieUniversität BonnGerhard-Domagk-Strasse 153121BonnGermany
| | - Julius B. Stückrath
- Mulliken Center for Theoretical ChemistryInstitut für Physikalische und Theoretische ChemieUniversität BonnBeringstrasse 453115BonnGermany
| | - Stefan Grimme
- Mulliken Center for Theoretical ChemistryInstitut für Physikalische und Theoretische ChemieUniversität BonnBeringstrasse 453115BonnGermany
| | - Andreas Gansäuer
- Kekulé-Institut für Organische Chemie und BiochemieUniversität BonnGerhard-Domagk-Strasse 153121BonnGermany
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14
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Hilche T, Reinsberg PH, Klare S, Liedtke T, Schäfer L, Gansäuer A. Design Platform for Sustainable Catalysis with Radicals: Electrochemical Activation of Cp 2 TiCl 2 for Catalysis Unveiled. Chemistry 2021; 27:4903-4912. [PMID: 33085978 PMCID: PMC7986168 DOI: 10.1002/chem.202004519] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Indexed: 12/17/2022]
Abstract
The combination of synthesis, rotating ring-disk electrode (RRDE) and cyclic voltammetry (CV) measurements, and computational investigations with the aid of DFT methods shows how a thiourea, a squaramide, and a bissulfonamide as additives affect the Eq Cr equilibrium of Cp2 TiCl2 . We have, for the first time, provided quantitative data for the Eq Cr equilibrium and have determined the stoichiometry of adduct formation of [Cp2 Ti(III)Cl2 ]- , [Cp2 Ti(III)Cl] and [Cp2 Ti(IV)Cl2 ] and the additives. By studying the structures of the complexes formed by DFT methods, we have established the Gibbs energies and enthalpies of complex formation as well as the adduct structures. The results not only demonstrate the correctness of our use of the Eq Cr equilibrium as predictor for sustainable catalysis. They are also a design platform for the development of novel additives in particular for enantioselective catalysis.
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Affiliation(s)
- Tobias Hilche
- Kekulé-Institut für Organische Chemie und BiochemieUniversität BonnGerhard-Domagk-Straße 153121BonnGermany
| | - Philip H. Reinsberg
- Institut für Physikalische und Theoretische Chemie, Universität BonnRömerstraße 16453117BonnGermany
| | - Sven Klare
- Kekulé-Institut für Organische Chemie und BiochemieUniversität BonnGerhard-Domagk-Straße 153121BonnGermany
| | - Theresa Liedtke
- Kekulé-Institut für Organische Chemie und BiochemieUniversität BonnGerhard-Domagk-Straße 153121BonnGermany
| | - Luise Schäfer
- Kekulé-Institut für Organische Chemie und BiochemieUniversität BonnGerhard-Domagk-Straße 153121BonnGermany
| | - Andreas Gansäuer
- Kekulé-Institut für Organische Chemie und BiochemieUniversität BonnGerhard-Domagk-Straße 153121BonnGermany
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15
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Martínez AR, Morales LP, Ojeda ED, Rodríguez MC, Rodríguez-García I. The Proven Versatility of Cp 2TiCl. J Org Chem 2020; 86:1311-1329. [PMID: 33147037 DOI: 10.1021/acs.joc.0c01233] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In the last two decades, titanocene monochloride has been postulated as a monoelectronic transfer reagent capable of catalyzing an important variety of chemical transformations. In this Perspective, our contributions to this growing field of research are summarized and analyzed. Especially known have been our contributions in C-C bond formation reactions, hydrogen-atom transfer from water to radicals, and isomerization reactions, as well as the development of a catalytic cycle that has subsequently allowed the preparation of a great variety of natural terpenes. It is also worth mentioning our contribution in the postulation of this single-electron transfer agent (SET) as a new green catalyst with a broad range of applications in organic and organometallic chemistry. The most significant catalytic processes developed by other research groups are also briefly described, with special emphasis on the reaction mechanisms involved. Finally, a reflection is made on the future trends in the research of this SET, aimed at consolidating this chemical as a new green reagent that will be widely used in fine chemistry, green chemistry, and industrial chemical processes.
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Affiliation(s)
- Antonio Rosales Martínez
- Department of Chemical Engineering, Escuela Politécnica Superior, University of Sevilla, 41011 Sevilla, Spain
| | - Laura Pozo Morales
- Department of Chemical Engineering, Escuela Politécnica Superior, University of Sevilla, 41011 Sevilla, Spain
| | - Emilio Díaz Ojeda
- Department of Chemical Engineering, Escuela Politécnica Superior, University of Sevilla, 41011 Sevilla, Spain
| | - María Castro Rodríguez
- Department of Chemical Engineering, Escuela Politécnica Superior, University of Sevilla, 41011 Sevilla, Spain
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16
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Fermi A, Gualandi A, Bergamini G, Cozzi PG. Shining Light on Ti
IV
Complexes: Exceptional Tools for Metallaphotoredox Catalysis. European J Org Chem 2020. [DOI: 10.1002/ejoc.202000966] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Andrea Fermi
- Dipartimento di Chimica "G. Ciamician" Università di Bologna via Selmi 2 40126 Bologna Italy
| | - Andrea Gualandi
- Dipartimento di Chimica "G. Ciamician" Università di Bologna via Selmi 2 40126 Bologna Italy
| | - Giacomo Bergamini
- Dipartimento di Chimica "G. Ciamician" Università di Bologna via Selmi 2 40126 Bologna Italy
| | - Pier Giorgio Cozzi
- Dipartimento di Chimica "G. Ciamician" Università di Bologna via Selmi 2 40126 Bologna Italy
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17
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Bezdek MJ, Pelczer I, Chirik PJ. Coordination-Induced N–H Bond Weakening in a Molybdenum Pyrrolidine Complex: Isotopic Labeling Provides Insight into the Pathway for H 2 Evolution. Organometallics 2020. [DOI: 10.1021/acs.organomet.0c00471] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Máté J. Bezdek
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - István Pelczer
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Paul J. Chirik
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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18
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Klare S, Gordon JP, Gansäuer A, RajanBabu TV, Nugent WA. The Reaction of β,γ-Epoxy Alcohols with Titanium(III) Reagents. A Proposed Role for Intramolecular Hydrogen Bonding. Tetrahedron 2019; 75:130662. [PMID: 32601512 PMCID: PMC7322769 DOI: 10.1016/j.tet.2019.130662] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Sven Klare
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Straβe 1, 53121 Bonn, Germany
| | - Jonathan P. Gordon
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210 USA
| | - Andreas Gansäuer
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Straβe 1, 53121 Bonn, Germany
| | - T. V. RajanBabu
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210 USA
| | - William A. Nugent
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210 USA
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19
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Carmona M, Ferrer J, Rodríguez R, Passarelli V, Lahoz FJ, García-Orduña P, Cañadillas-Delgado L, Carmona D. Reversible Activation of Water by an Air- and Moisture-Stable Frustrated Rhodium Nitrogen Lewis Pair. Chemistry 2019; 25:13665-13670. [PMID: 31353749 DOI: 10.1002/chem.201902452] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/12/2019] [Indexed: 12/15/2022]
Abstract
[Cp*Rh(κ3 N,N',P-L)][SbF6 ] (Cp*=C5 Me5 ), bearing a guanidine-derived phosphano ligand L, behaves as a "dormant" frustrated Lewis pair and activates H2 and H2 O in a reversible manner. When D2 O is employed, a facile H/D exchange at the Cp* ring takes place through sequential C(sp3 )-H bond activation.
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Affiliation(s)
- María Carmona
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC-Universidad de Zaragoza, Pedro Cerbuna 12, 50009, Zaragoza, Spain
| | - Joaquina Ferrer
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC-Universidad de Zaragoza, Pedro Cerbuna 12, 50009, Zaragoza, Spain
| | - Ricardo Rodríguez
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC-Universidad de Zaragoza, Pedro Cerbuna 12, 50009, Zaragoza, Spain
| | - Vincenzo Passarelli
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC-Universidad de Zaragoza, Pedro Cerbuna 12, 50009, Zaragoza, Spain.,Centro Universitario de la Defensa, Ctra. Huesca s/n, 50090, Zaragoza, Spain
| | - Fernando J Lahoz
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC-Universidad de Zaragoza, Pedro Cerbuna 12, 50009, Zaragoza, Spain
| | - Pilar García-Orduña
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC-Universidad de Zaragoza, Pedro Cerbuna 12, 50009, Zaragoza, Spain
| | - Laura Cañadillas-Delgado
- Centro Universitario de la Defensa, Ctra. Huesca s/n, 50090, Zaragoza, Spain.,Institut Laue-Langevin, 71 Avenue des Martyrs, Grenoble, 38042, France
| | - Daniel Carmona
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC-Universidad de Zaragoza, Pedro Cerbuna 12, 50009, Zaragoza, Spain
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20
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Liedtke T, Hilche T, Klare S, Gansäuer A. Condition Screening for Sustainable Catalysis in Single-Electron Steps by Cyclic Voltammetry: Additives and Solvents. CHEMSUSCHEM 2019; 12:3166-3171. [PMID: 30779429 DOI: 10.1002/cssc.201900344] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 02/18/2019] [Indexed: 06/09/2023]
Abstract
Cyclic voltammetry-based screening method for Cp2 TiX-catalyzed reactions is extended to the screening of solvents other than tetrahydrofuran for bulk electrolysis of the catalyst and radical arylation. It was found that CH3 CN can be used as a solvent for both processes without additives. Furthermore, in tetrahydrofuran, squaramide L2 is more efficient than the previously reported supramolecular halide binder, Schreiner's thiourea L1. The results extend the usefulness of the proposed time and resource-efficient screening method for designing catalysis reactions in single-electron steps.
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Affiliation(s)
- Theresa Liedtke
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Straße 1, 53121, Bonn, Germany
| | - Tobias Hilche
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Straße 1, 53121, Bonn, Germany
| | - Sven Klare
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Straße 1, 53121, Bonn, Germany
| | - Andreas Gansäuer
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Straße 1, 53121, Bonn, Germany
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21
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Kim D, Rahaman SMW, Mercado BQ, Poli R, Holland PL. Roles of Iron Complexes in Catalytic Radical Alkene Cross-Coupling: A Computational and Mechanistic Study. J Am Chem Soc 2019; 141:7473-7485. [PMID: 31025567 PMCID: PMC6953484 DOI: 10.1021/jacs.9b02117] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A growing and useful class of alkene coupling reactions involve hydrogen atom transfer (HAT) from a metal-hydride species to an alkene to form a free radical, which is responsible for subsequent bond formation. Here, we use a combination of experimental and computational investigations to map out the mechanistic details of iron-catalyzed reductive alkene cross-coupling, an important representative of the HAT alkene reactions. We are able to explain several observations that were previously mysterious. First, the rate-limiting step in the catalytic cycle is the formation of the reactive Fe-H intermediate, elucidating the importance of the choice of reductant. Second, the success of the catalytic system is attributable to the exceptionally weak (17 kcal/mol) Fe-H bond, which performs irreversible HAT to alkenes in contrast to previous studies on isolable hydride complexes where this addition was reversible. Third, the organic radical intermediates can reversibly form organometallic species, which helps to protect the free radicals from side reactions. Fourth, the previously accepted quenching of the postcoupling radical through stepwise electron transfer/proton transfer is not as favorable as alternative mechanisms. We find that there are two feasible pathways. One uses concerted proton-coupled electron transfer (PCET) from an iron(II) ethanol complex, which is facilitated because the O-H bond dissociation free energy is lowered by 30 kcal/mol upon metal binding. In an alternative pathway, an O-bound enolate-iron(III) complex undergoes proton shuttling from an iron-bound alcohol. These kinetic, spectroscopic, and computational studies identify key organometallic species and PCET steps that control selectivity and reactivity in metal-catalyzed HAT alkene coupling, and create a firm basis for elucidation of mechanisms in the growing class of HAT alkene cross-coupling reactions.
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Affiliation(s)
- Dongyoung Kim
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
| | - S. M. Wahidur Rahaman
- LCC-CNRS, Université de Toulouse, INPT, 205 Route de Narbonne, BP 44099, F-31077 Toulouse Cedex 4, France
| | - Brandon Q. Mercado
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
| | - Rinaldo Poli
- LCC-CNRS, Université de Toulouse, INPT, 205 Route de Narbonne, BP 44099, F-31077 Toulouse Cedex 4, France
| | - Patrick L. Holland
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
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22
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Beaumier EP, Pearce AJ, See XY, Tonks IA. Modern applications of low-valent early transition metals in synthesis and catalysis. Nat Rev Chem 2019; 3:15-34. [PMID: 30989127 PMCID: PMC6462221 DOI: 10.1038/s41570-018-0059-x] [Citation(s) in RCA: 132] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Low-valent early transition metals are often intrinsically highly reactive as a result of their strong propensity toward oxidation to more stable high-valent states. Harnessing these highly reducing complexes for productive reactivity is potentially powerful for C-C bond construction, organic reductions, small-molecule activation and many other reactions that offer orthogonal chemoselectivity and/or regioselectivity patterns to processes promoted by late transition metals. Recent years have seen many exciting new applications of low-valent metals through building new catalytic and/or multicomponent reaction manifolds out of classical reactivity patterns. In this Review, we survey new methods that employ early transition metals and invoke low-valent precursors or intermediates in order to identify common themes and strategies in synthesis and catalysis.
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Affiliation(s)
- Evan P. Beaumier
- Department of Chemistry, University of Minnesota, Minneapolis, MN, USA
| | - Adam J. Pearce
- Department of Chemistry, University of Minnesota, Minneapolis, MN, USA
| | - Xin Yi See
- Department of Chemistry, University of Minnesota, Minneapolis, MN, USA
| | - Ian A. Tonks
- Department of Chemistry, University of Minnesota, Minneapolis, MN, USA
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23
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Bartulovich CO, Flowers RA. Coordination-induced O–H bond weakening in Sm(ii)-water complexes. Dalton Trans 2019; 48:16142-16147. [DOI: 10.1039/c9dt03352a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Coordination of water to low-valent Sm leads to O–H bond-weakening that enables PCET to substrates.
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Affiliation(s)
| | - R. A. Flowers
- Department of Chemistry Lehigh University
- Bethlehem
- USA
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24
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Gordon J, Hildebrandt S, Dewese KR, Klare S, Gansäuer A, RajanBabu TV, Nugent WA. Demystifying Cp 2Ti(H)Cl and its Enigmatic Role in the Reactions of Epoxides with Cp 2TiCl. Organometallics 2018; 37:4801-4809. [PMID: 30733623 DOI: 10.1021/acs.organomet.8b00793] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The role of Cp2Ti(H)Cl in the reactions of Cp2TiCl with trisubstituted epoxides has been investigated in a combined experimental and computational study. Although Cp2Ti(H)Cl has generally been regarded as a robust species, its decomposition to Cp2TiCl and molecular hydrogen was found to be exothermic (ΔG = -11 kcal/mol when the effects of THF solvation are considered). In laboratory studies, Cp2Ti(H)Cl was generated using the reaction of 1,2-epoxy-1-methylcyclohexane with Cp2TiCl as a model. Rapid evolution of hydrogen gas was demonstrated, indicating that Cp2Ti(H)Cl is indeed a thermally unstable molecule, which undergoes intermolecular reductive elimination of hydrogen under the reaction conditions. The stoichiometry of the reaction (Cp2TiCl:epoxide = 1:1) and the quantity of hydrogen produced (1 mole per 2 moles of epoxide) is consistent with this assertion. The diminished yield of allylic alcohol from these reactions under the conditions of protic versus aprotic catalysis can be understood in terms of the predominant titanium(III) present in solution. Under the conditions of protic catalysis, Cp2TiCl complexes with collidine hydrochloride and the titanium(III) center is less available for "cross-disproportionation" with carbon-centered radicals; this leads to by-products from radical capture by hydrogen atom transfer, resulting in a saturated alcohol.
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Affiliation(s)
- Jonathan Gordon
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA
| | - Sven Hildebrandt
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany
| | - Kendra R Dewese
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA
| | - Sven Klare
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany
| | - Andreas Gansäuer
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany
| | - T V RajanBabu
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA
| | - William A Nugent
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA
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25
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Yan J, Yang Z, Chen Y, Chang Y, Lyu C, Luo C, Cheng M, Hsu H. Activation of O−H and C−O Bonds in Water and Methanol by a Vanadium‐Bound Thiyl Radical. Chemistry 2018; 24:15190-15194. [DOI: 10.1002/chem.201803431] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 07/17/2018] [Indexed: 12/21/2022]
Affiliation(s)
- Jyun‐An Yan
- Department of ChemistryNational Cheng Kung University, No. 1 University Rd. 701 Tainan Taiwan
| | - Zi‐Kuan Yang
- Department of ChemistryNational Cheng Kung University, No. 1 University Rd. 701 Tainan Taiwan
| | - Yu‐Sen Chen
- Department of ChemistryNational Cheng Kung University, No. 1 University Rd. 701 Tainan Taiwan
| | - Ya‐Ho Chang
- Department of ChemistryNational Cheng Kung University, No. 1 University Rd. 701 Tainan Taiwan
| | - Chiao‐Ling Lyu
- Department of ChemistryNational Cheng Kung University, No. 1 University Rd. 701 Tainan Taiwan
| | - Chun‐Gang Luo
- Department of ChemistryNational Cheng Kung University, No. 1 University Rd. 701 Tainan Taiwan
| | - Mu‐Jeng Cheng
- Department of ChemistryNational Cheng Kung University, No. 1 University Rd. 701 Tainan Taiwan
| | - Hua‐Fen Hsu
- Department of ChemistryNational Cheng Kung University, No. 1 University Rd. 701 Tainan Taiwan
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26
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Streuff J, Himmel D, Younas SL. Understanding titanium-catalysed radical-radical reactions: a DFT study unravels the complex kinetics of ketone-nitrile couplings. Dalton Trans 2018; 47:5072-5082. [PMID: 29561012 DOI: 10.1039/c8dt00643a] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The computational investigation of a titanium-catalysed reductive radical-radical coupling is reported. The results match the conclusions from an earlier experimental study and enable a further interpretation of the previously observed complex reaction kinetics. Furthermore, the interplay between neutral and cationic reaction pathways in titanium(iii)-catalysed reactions is investigated for the first time. The results show that hydrochloride additives and reaction byproducts play an important role in the respective equilibria. A full reaction profile is assembled and the computed activation barrier is found to be in reasonable agreement with the experiment. The conclusions are of fundamental importance to the field of low-valent titanium catalysis and the understanding of related catalytic radical-radical coupling reactions.
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Affiliation(s)
- Jan Streuff
- Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
| | - Daniel Himmel
- Institut für Anorganische und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Sara L Younas
- Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
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27
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Richrath RB, Olyschläger T, Hildebrandt S, Enny DG, Fianu GD, Flowers RA, Gansäuer A. Cp 2 TiX Complexes for Sustainable Catalysis in Single-Electron Steps. Chemistry 2018; 24:6371-6379. [PMID: 29327511 DOI: 10.1002/chem.201705707] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Indexed: 12/18/2022]
Abstract
We present a combined electrochemical, kinetic, and synthetic study with a novel and easily accessible class of titanocene catalysts for catalysis in single-electron steps. The tailoring of the electronic properties of our Cp2 TiX-catalysts that are prepared in situ from readily available Cp2 TiX2 is achieved by varying the anionic ligand X. Of the complexes investigated, Cp2 TiOMs proved to be either equal or substantially superior to the best catalysts developed earlier. The kinetic and thermodynamic properties pertinent to catalysis have been determined. They allow a mechanistic understanding of the subtle interplay of properties required for an efficient oxidative addition and reduction. Therefore, our study highlights that efficient catalysts do not require the elaborate covalent modification of the cyclopentadienyl ligands.
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Affiliation(s)
- Ruben B Richrath
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard Domagk-Str. 1, 53121, Bonn, Germany
| | - Theresa Olyschläger
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard Domagk-Str. 1, 53121, Bonn, Germany
| | - Sven Hildebrandt
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard Domagk-Str. 1, 53121, Bonn, Germany
| | - Daniel G Enny
- Department of Chemistry, Lehigh University, Bethlehem, PA, 18015, USA
| | - Godfred D Fianu
- Department of Chemistry, Lehigh University, Bethlehem, PA, 18015, USA
| | - Robert A Flowers
- Department of Chemistry, Lehigh University, Bethlehem, PA, 18015, USA
| | - Andreas Gansäuer
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard Domagk-Str. 1, 53121, Bonn, Germany
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28
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Yeung D, Penafiel J, Zijlstra HS, McIndoe JS. Oxidation of Titanocene(III): The Deceptive Simplicity of a Color Change. Inorg Chem 2017; 57:457-461. [DOI: 10.1021/acs.inorgchem.7b02705] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Darien Yeung
- Department of Chemistry, University of Victoria, PO Box 1700
STN CSC, Victoria, BC V8W 2Y2, Canada
| | - Johanne Penafiel
- Department of Chemistry, University of Victoria, PO Box 1700
STN CSC, Victoria, BC V8W 2Y2, Canada
| | - Harmen S. Zijlstra
- Department of Chemistry, University of Victoria, PO Box 1700
STN CSC, Victoria, BC V8W 2Y2, Canada
| | - J. Scott McIndoe
- Department of Chemistry, University of Victoria, PO Box 1700
STN CSC, Victoria, BC V8W 2Y2, Canada
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29
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Martínez AR, Rodríguez MC, Rodríguez-García I, Morales LP, Maecker RNR. Titanocene dichloride: A new green reagent in organic chemistry. CHINESE JOURNAL OF CATALYSIS 2017. [DOI: 10.1016/s1872-2067(17)62894-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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30
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Castro Rodríguez M, Rodríguez García I, Rodríguez Maecker RN, Pozo Morales L, Oltra JE, Rosales Martínez A. Cp2TiCl: An Ideal Reagent for Green Chemistry? Org Process Res Dev 2017. [DOI: 10.1021/acs.oprd.7b00098] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- María Castro Rodríguez
- Department
of Chemical Engineering, Escuela Politécnica Superior, University of Sevilla, 41011 Sevilla, Spain
| | | | | | - Laura Pozo Morales
- Department
of Chemical Engineering, Escuela Politécnica Superior, University of Sevilla, 41011 Sevilla, Spain
| | - J. Enrique Oltra
- Department
of Organic Chemistry, Faculty of Science, University of Granada, 18071 Granada, Spain
| | - Antonio Rosales Martínez
- Department
of Chemical Engineering, Escuela Politécnica Superior, University of Sevilla, 41011 Sevilla, Spain
- Petrochemical
Engineering, Universidad de las Fuerzas Armadas-ESPE, 050150 Latacunga, Ecuador
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31
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Just-Baringo X, Clark J, Gutmann MJ, Procter DJ. Selective Synthesis of Cyclooctanoids by Radical Cyclization of Seven-Membered Lactones: Neutron Diffraction Study of the Stereoselective Deuteration of a Chiral Organosamarium Intermediate. Angew Chem Int Ed Engl 2016; 55:12499-502. [PMID: 27600354 PMCID: PMC5113801 DOI: 10.1002/anie.201606792] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Indexed: 11/09/2022]
Abstract
Seven-membered lactones undergo selective SmI2 -H2 O-promoted radical cyclization to form substituted cyclooctanols. The products arise from an exo-mode of cyclization rather than the usual endo-attack employed in the few radical syntheses of cyclooctanes. The process is terminated by the quenching of a chiral benzylic samarium. A labeling experiment and neutron diffraction study have been used for the first time to probe the configuration and highly diastereoselective deuteration of a chiral organosamarium intermediate.
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Affiliation(s)
| | - Jemma Clark
- School of Chemistry, University of Manchester, Manchester, M13 9PL, UK
| | - Matthias J Gutmann
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX, UK
| | - David J Procter
- School of Chemistry, University of Manchester, Manchester, M13 9PL, UK.
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32
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Funken N, Mühlhaus F, Gansäuer A. General, Highly Selective Synthesis of 1,3- and 1,4-Difunctionalized Building Blocks by Regiodivergent Epoxide Opening. Angew Chem Int Ed Engl 2016; 55:12030-4. [PMID: 27600090 DOI: 10.1002/anie.201606064] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 07/22/2016] [Indexed: 12/31/2022]
Abstract
We describe a regiodivergent epoxide opening (REO) featuring a catalyst-controlled synthesis of enantiomerically and diastereomerically highly enriched or pure syn- and anti- 1,3- and 1,4-difunctionalized building blocks from a common epoxide precursor. The REO is attractive for natural product synthesis and as a branching reaction for diversity-oriented synthesis with epoxides.
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Affiliation(s)
- Nico Funken
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany
| | - Felix Mühlhaus
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany
| | - Andreas Gansäuer
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany.
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33
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Funken N, Mühlhaus F, Gansäuer A. General, Highly Selective Synthesis of 1,3- and 1,4-Difunctionalized Building Blocks by Regiodivergent Epoxide Opening. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201606064] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Nico Funken
- Kekulé-Institut für Organische Chemie und Biochemie; Universität Bonn; Gerhard-Domagk-Str. 1 53121 Bonn Germany
| | - Felix Mühlhaus
- Kekulé-Institut für Organische Chemie und Biochemie; Universität Bonn; Gerhard-Domagk-Str. 1 53121 Bonn Germany
| | - Andreas Gansäuer
- Kekulé-Institut für Organische Chemie und Biochemie; Universität Bonn; Gerhard-Domagk-Str. 1 53121 Bonn Germany
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34
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Just-Baringo X, Clark J, Gutmann MJ, Procter DJ. Selective Synthesis of Cyclooctanoids by Radical Cyclization of Seven-Membered Lactones: Neutron Diffraction Study of the Stereoselective Deuteration of a Chiral Organosamarium Intermediate. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201606792] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
| | - Jemma Clark
- School of Chemistry; University of Manchester; Manchester M13 9PL UK
| | - Matthias J. Gutmann
- ISIS Facility; Rutherford Appleton Laboratory; Chilton, Didcot Oxfordshire OX11 0QX UK
| | - David J. Procter
- School of Chemistry; University of Manchester; Manchester M13 9PL UK
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35
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Rosales A, Rodríguez-García I. Cp2TiCl/D2O/Mn, a formidable reagent for the deuteration of organic compounds. Beilstein J Org Chem 2016; 12:1585-9. [PMID: 27559410 PMCID: PMC4979672 DOI: 10.3762/bjoc.12.154] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 07/13/2016] [Indexed: 11/25/2022] Open
Abstract
Cp2TiCl/D2O/Mn is an efficient combination, sustainable and cheap reagent that mediates the D-atom transfer from D2O to different functional groups and can contribute to the synthesis of new deuterated organic compounds under friendly experimental conditions and with great economic advantages.
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Affiliation(s)
- Antonio Rosales
- Department of Chemical and Environmental Engineering, Escuela Politécnica Superior, University of Sevilla, 41011 Sevilla, Spain; Petrochemical Engineering, Universidad de las Fuerzas Armadas-ESPE, 050150 Latacunga, Ecuador
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36
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Abstract
Redox events in which an electron and proton are exchanged in a concerted elementary step are commonly referred to as proton-coupled electron transfers (PCETs). PCETs are known to operate in numerous important biological redox processes, as well as recent inorganic technologies for small molecule activation. These studies suggest that PCET catalysis might also function as a general mode of substrate activation in organic synthesis. Over the past three years, our group has worked to advance this hypothesis and to demonstrate the synthetic utility of PCET through the development of novel catalytic radical chemistries. The central aim of these efforts has been to demonstrate the ability of PCET to homolytically activate a wide variety of common organic functional groups that are energetically inaccessible using known molecular H atom transfer catalysts. To do so, we made use of a simple formalism first introduced by Mayer and co-workers that allowed us to predict the thermodynamic capacity of any oxidant/base or reductant/acid pair to formally add or remove H· from a given substrate. With this insight, we were able to rationally select catalyst combinations thermodynamically competent to homolyze the extraordinarily strong E-H σ-bonds found in many common protic functional groups (BDFEs > 100 kcal/mol) or to form unusually weak bonds to hydrogen via the reductive action of common organic π-systems (BDFEs < 35 kcal/mol). These ideas were reduced to practice through the development of new catalyst systems for reductive PCET activations of ketones and oxidative PCET activation of amide N-H bonds to directly furnish reactive ketyl and amidyl radicals, respectively. In both systems, the reaction outcomes were found to be successfully predicted using the effective bond strength formalism, suggesting that these simple thermochemical considerations can provide useful and actionable insights into PCET reaction design. The ability of PCET catalysis to control enantioselectivity in free radical processes has also been established. Specifically, multisite PCET requires the formation of a pre-equilibrium hydrogen bond between the substrate and a proton donor/acceptor prior to charge transfer. We recognized that these H-bond interfaces persist following the PCET event, resulting in the formation of noncovalent complexes of the nascent radical intermediates. When chiral proton donors/acceptors are employed, this association can provide a basis for asymmetric induction in subsequent bond-forming steps. We discuss our efforts to capitalize on this understanding via the development of a catalytic protocol for enantioselective aza-pinacol cyclizations. Lastly, we highlight an alternative PCET mechanism that exploits the ability of redox-active metals to homolytically weaken the bonds in coordinated ligands, enabling nominally strong bonds (BDFEs ∼ 100 kcal) to be abstracted by weak H atom acceptors with concomitant oxidation of the metal center. This "soft homolysis" mechanism enables the generation of metalated intermediates from protic substrates under completely neutral conditions. The first example of this form of catalysis is presented in the context of a catalytic C-N bond forming reaction jointly mediated by bulky titanocene complexes and the stable nitroxyl radical TEMPO.
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Affiliation(s)
- Emily C. Gentry
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Robert R. Knowles
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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37
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Chciuk TV, Anderson WR, Flowers RA. Proton-Coupled Electron Transfer in the Reduction of Carbonyls by Samarium Diiodide–Water Complexes. J Am Chem Soc 2016; 138:8738-41. [DOI: 10.1021/jacs.6b05879] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Tesia V. Chciuk
- Department of Chemistry, Lehigh University, 6 E. Packer Avenue, Bethlehem, Pennsylvania 18015, United States
| | - William R. Anderson
- Department of Chemistry, Lehigh University, 6 E. Packer Avenue, Bethlehem, Pennsylvania 18015, United States
| | - Robert A. Flowers
- Department of Chemistry, Lehigh University, 6 E. Packer Avenue, Bethlehem, Pennsylvania 18015, United States
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38
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Chciuk TV, Anderson WR, Flowers RA. High‐Affinity Proton Donors Promote Proton‐Coupled Electron Transfer by Samarium Diiodide. Angew Chem Int Ed Engl 2016; 55:6033-6. [DOI: 10.1002/anie.201601474] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 03/09/2016] [Indexed: 01/03/2023]
Affiliation(s)
- Tesia V. Chciuk
- Department of Chemistry Lehigh University 6 E. Packer Ave. Bethlehem PA 18015 USA
| | - William R. Anderson
- Department of Chemistry Lehigh University 6 E. Packer Ave. Bethlehem PA 18015 USA
| | - Robert A. Flowers
- Department of Chemistry Lehigh University 6 E. Packer Ave. Bethlehem PA 18015 USA
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39
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Chciuk TV, Anderson WR, Flowers RA. High‐Affinity Proton Donors Promote Proton‐Coupled Electron Transfer by Samarium Diiodide. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201601474] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Tesia V. Chciuk
- Department of Chemistry Lehigh University 6 E. Packer Ave. Bethlehem PA 18015 USA
| | - William R. Anderson
- Department of Chemistry Lehigh University 6 E. Packer Ave. Bethlehem PA 18015 USA
| | - Robert A. Flowers
- Department of Chemistry Lehigh University 6 E. Packer Ave. Bethlehem PA 18015 USA
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40
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Luo Y, Wu Y, Wang Y, Sun H, Xie Z, Zhang W, Gao Z. Ethanol promoted titanocene Lewis acid catalyzed synthesis of quinazoline derivatives. RSC Adv 2016. [DOI: 10.1039/c6ra14583c] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
An efficient strategy to activate air-stable Lewis acid precursor Cp2TiCl2 with alcoholic solvent for the rapid synthesis of quinazoline derivatives.
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Affiliation(s)
- Yanlong Luo
- Key Laboratory of Applied Surface and Colloid Chemistry
- MOE
- School of Chemistry and Chemical Engineering
- Shaanxi Normal University
- Xi’an 710062
| | - Ya Wu
- Key Laboratory of Applied Surface and Colloid Chemistry
- MOE
- School of Chemistry and Chemical Engineering
- Shaanxi Normal University
- Xi’an 710062
| | - Yunyun Wang
- Key Laboratory of Applied Surface and Colloid Chemistry
- MOE
- School of Chemistry and Chemical Engineering
- Shaanxi Normal University
- Xi’an 710062
| | - Huaming Sun
- Key Laboratory of Applied Surface and Colloid Chemistry
- MOE
- School of Chemistry and Chemical Engineering
- Shaanxi Normal University
- Xi’an 710062
| | - Zunyuan Xie
- Key Laboratory of Applied Surface and Colloid Chemistry
- MOE
- School of Chemistry and Chemical Engineering
- Shaanxi Normal University
- Xi’an 710062
| | - Weiqiang Zhang
- Key Laboratory of Applied Surface and Colloid Chemistry
- MOE
- School of Chemistry and Chemical Engineering
- Shaanxi Normal University
- Xi’an 710062
| | - Ziwei Gao
- Key Laboratory of Applied Surface and Colloid Chemistry
- MOE
- School of Chemistry and Chemical Engineering
- Shaanxi Normal University
- Xi’an 710062
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41
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Diaba F, Gómez-Bengoa E, Cuerva JM, Bonjoch J, Justicia J. Synthesis of substituted γ- and δ-lactams based on titanocene(iii)-catalysed radical cyclisations of trichloroacetamides. RSC Adv 2016. [DOI: 10.1039/c6ra12180b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Straightforward synthesis of dehalogenated γ- and δ-lactams based on a Cp2TiCl-catalysed radical cyclisation of trichloroacetamides under mild conditions.
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Affiliation(s)
- Faïza Diaba
- Laboratori de Química Orgànica
- Facultat de Farmàcia
- IBUB
- Universitat de Barcelona
- 08028-Barcelona
| | - Enrique Gómez-Bengoa
- Departamento de Química Orgánica I
- Universidad del País Vasco
- 20018 San Sebastián
- Spain
| | - Juan M. Cuerva
- Departamento de Química Orgánica
- Facultad de Ciencias
- Universidad de Granada
- 18071-Granada
- Spain
| | - Josep Bonjoch
- Laboratori de Química Orgànica
- Facultat de Farmàcia
- IBUB
- Universitat de Barcelona
- 08028-Barcelona
| | - José Justicia
- Departamento de Química Orgánica
- Facultad de Ciencias
- Universidad de Granada
- 18071-Granada
- Spain
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42
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Zhang YQ, Jakoby V, Stainer K, Schmer A, Klare S, Bauer M, Grimme S, Cuerva JM, Gansäuer A. Amid-substituierte Titanocene für die H-Atom-Transfer-Katalyse. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201509548] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Yong-Qiang Zhang
- Kekulé-Institut für Organische Chemie und Biochemie; Universität Bonn; Gerhard-Domagk-Straße 1 53121 Bonn Deutschland
| | - Verena Jakoby
- Kekulé-Institut für Organische Chemie und Biochemie; Universität Bonn; Gerhard-Domagk-Straße 1 53121 Bonn Deutschland
| | - Katharina Stainer
- Kekulé-Institut für Organische Chemie und Biochemie; Universität Bonn; Gerhard-Domagk-Straße 1 53121 Bonn Deutschland
| | - Alexander Schmer
- Kekulé-Institut für Organische Chemie und Biochemie; Universität Bonn; Gerhard-Domagk-Straße 1 53121 Bonn Deutschland
| | - Sven Klare
- Kekulé-Institut für Organische Chemie und Biochemie; Universität Bonn; Gerhard-Domagk-Straße 1 53121 Bonn Deutschland
| | - Mirko Bauer
- Mulliken Center for Theoretical Chemistry, Institut für Physikalische Chemie und Theoretische Chemie; Universität Bonn; Beringstraße 4 53115 Bonn Deutschland
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry, Institut für Physikalische Chemie und Theoretische Chemie; Universität Bonn; Beringstraße 4 53115 Bonn Deutschland
| | - Juan Manuel Cuerva
- Department of Organic Chemistry, Faculty of Sciences; Universität Granada; 18071 Granada Spanien
| | - Andreas Gansäuer
- Kekulé-Institut für Organische Chemie und Biochemie; Universität Bonn; Gerhard-Domagk-Straße 1 53121 Bonn Deutschland
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43
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Zhang YQ, Jakoby V, Stainer K, Schmer A, Klare S, Bauer M, Grimme S, Cuerva JM, Gansäuer A. Amide-Substituted Titanocenes in Hydrogen-Atom Transfer Catalysis. Angew Chem Int Ed Engl 2015; 55:1523-6. [DOI: 10.1002/anie.201509548] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Indexed: 12/18/2022]
Affiliation(s)
- Yong-Qiang Zhang
- Kekulé-Institut für Organische Chemie und Biochemie; Universität Bonn; Gerhard-Domagk-Straße 1 53121 Bonn Germany
| | - Verena Jakoby
- Kekulé-Institut für Organische Chemie und Biochemie; Universität Bonn; Gerhard-Domagk-Straße 1 53121 Bonn Germany
| | - Katharina Stainer
- Kekulé-Institut für Organische Chemie und Biochemie; Universität Bonn; Gerhard-Domagk-Straße 1 53121 Bonn Germany
| | - Alexander Schmer
- Kekulé-Institut für Organische Chemie und Biochemie; Universität Bonn; Gerhard-Domagk-Straße 1 53121 Bonn Germany
| | - Sven Klare
- Kekulé-Institut für Organische Chemie und Biochemie; Universität Bonn; Gerhard-Domagk-Straße 1 53121 Bonn Germany
| | - Mirko Bauer
- Mulliken Center for Theoretical Chemistry, Institut für Physikalische Chemie und Theoretische Chemie; Universität Bonn; Beringstraße 4 53115 Bonn Germany
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry, Institut für Physikalische Chemie und Theoretische Chemie; Universität Bonn; Beringstraße 4 53115 Bonn Germany
| | - Juan Manuel Cuerva
- Department of Organic Chemistry, Faculty of Sciences; Universität Granada; 18071 Granada Spain
| | - Andreas Gansäuer
- Kekulé-Institut für Organische Chemie und Biochemie; Universität Bonn; Gerhard-Domagk-Straße 1 53121 Bonn Germany
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44
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Streuff J, Feurer M, Frey G, Steffani A, Kacprzak S, Weweler J, Leijendekker LH, Kratzert D, Plattner DA. Mechanism of the TiIII-Catalyzed Acyloin-Type Umpolung: A Catalyst-Controlled Radical Reaction. J Am Chem Soc 2015; 137:14396-405. [DOI: 10.1021/jacs.5b09223] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Jan Streuff
- Institut für Organische
Chemie, ‡Institut
für Physikalische Chemie, and §Institut für Anorganische
und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr.
21, 79104 Freiburg, Germany
| | - Markus Feurer
- Institut für Organische
Chemie, ‡Institut
für Physikalische Chemie, and §Institut für Anorganische
und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr.
21, 79104 Freiburg, Germany
| | - Georg Frey
- Institut für Organische
Chemie, ‡Institut
für Physikalische Chemie, and §Institut für Anorganische
und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr.
21, 79104 Freiburg, Germany
| | - Alberto Steffani
- Institut für Organische
Chemie, ‡Institut
für Physikalische Chemie, and §Institut für Anorganische
und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr.
21, 79104 Freiburg, Germany
| | - Sylwia Kacprzak
- Institut für Organische
Chemie, ‡Institut
für Physikalische Chemie, and §Institut für Anorganische
und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr.
21, 79104 Freiburg, Germany
| | - Jens Weweler
- Institut für Organische
Chemie, ‡Institut
für Physikalische Chemie, and §Institut für Anorganische
und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr.
21, 79104 Freiburg, Germany
| | - Leonardus H. Leijendekker
- Institut für Organische
Chemie, ‡Institut
für Physikalische Chemie, and §Institut für Anorganische
und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr.
21, 79104 Freiburg, Germany
| | - Daniel Kratzert
- Institut für Organische
Chemie, ‡Institut
für Physikalische Chemie, and §Institut für Anorganische
und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr.
21, 79104 Freiburg, Germany
| | - Dietmar A. Plattner
- Institut für Organische
Chemie, ‡Institut
für Physikalische Chemie, and §Institut für Anorganische
und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr.
21, 79104 Freiburg, Germany
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45
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Rosales A, Rodríguez-García I, Muñoz-Bascón J, Roldan-Molina E, Padial NM, Morales LP, García-Ocaña M, Oltra JE. The Nugent Reagent: A Formidable Tool in Contemporary Radical and Organometallic Chemistry. European J Org Chem 2015. [DOI: 10.1002/ejoc.201500292] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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46
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Morra E, Maurelli S, Chiesa M, Van Doorslaer S. Probing the coordination environment of Ti3+ ions coordinated to nitrogen-containing Lewis bases. Phys Chem Chem Phys 2015. [DOI: 10.1039/c5cp03417e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A combined EPR and DFT study on model systems reveals fingerprint 14N hyperfine and quadrupole data to identify binding of nitrogen-containing Lewis bases to Ti(iii).
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Affiliation(s)
- E. Morra
- Dipartimento di Chimica
- University of Torino Via Giuria
- 7-10125 Torino
- Italy
- University of Antwerp
| | - S. Maurelli
- Dipartimento di Chimica
- University of Torino Via Giuria
- 7-10125 Torino
- Italy
| | - M. Chiesa
- Dipartimento di Chimica
- University of Torino Via Giuria
- 7-10125 Torino
- Italy
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47
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Szostak M, Spain M, Eberhart AJ, Procter DJ. Mechanism of SmI2/Amine/H2O-Promoted Chemoselective Reductions of Carboxylic Acid Derivatives (Esters, Acids, and Amides) to Alcohols. J Org Chem 2014; 79:11988-2003. [DOI: 10.1021/jo5018525] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Michal Szostak
- Department
of Chemistry, Rutgers University, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Malcolm Spain
- School
of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Andrew J. Eberhart
- School
of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - David J. Procter
- School
of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
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48
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Rosales A, Muñoz-Bascón J, Roldan-Molina E, Castañeda MA, Padial NM, Gansäuer A, Rodríguez-García I, Oltra JE. Selective Reduction of Aromatic Ketones in Aqueous Medium Mediated by Ti(III)/Mn: A Revised Mechanism. J Org Chem 2014; 79:7672-6. [DOI: 10.1021/jo501141y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Antonio Rosales
- Centro
de Investigación, Estudios y Desarrollo de Ingeniería
(CIEDI); Ingeniería Agroindustrial y Alimentos, Universidad de las Américas, 170513 Quito, Ecuador
| | - Juan Muñoz-Bascón
- Departamento
Química Orgánica, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva s/n, 18071 Granada, Spain
| | - Esther Roldan-Molina
- Departamento
Química Orgánica, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva s/n, 18071 Granada, Spain
| | - Mayra A. Castañeda
- Centro
de Investigación, Estudios y Desarrollo de Ingeniería
(CIEDI); Ingeniería Agroindustrial y Alimentos, Universidad de las Américas, 170513 Quito, Ecuador
| | - Natalia M. Padial
- Departamento
Química Orgánica, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva s/n, 18071 Granada, Spain
| | - Andreas Gansäuer
- Kekulé-Institut
für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Strasse 1, 53127 Bonn, Germany
| | | | - J. Enrique Oltra
- Departamento
Química Orgánica, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva s/n, 18071 Granada, Spain
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49
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Morcillo SP, Miguel D, Resa S, Martín-Lasanta A, Millán A, Choquesillo-Lazarte D, García-Ruiz JM, Mota AJ, Justicia J, Cuerva JM. Ti(III)-catalyzed cyclizations of ketoepoxypolyprenes: control over the number of rings and unexpected stereoselectivities. J Am Chem Soc 2014; 136:6943-51. [PMID: 24766517 DOI: 10.1021/ja411942h] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We describe a new strategy to control the number of cyclization steps in bioinspired radical (poly)cyclizations involving epoxypolyenes containing keto units positioned along the polyene chain. This approach provides an unprecedentedly straightforward access to natural terpenoids with pendant unsaturated side chains. Additionally, in the case of bi- and tricyclizations, decalins with cis stereochemistry have been obtained as a consequence of the presence of the ketone. The preferential formation of cis-fused adducts was rationalized using DFT calculations. This result is completely unprecedented in biomimetic cyclizations and permits the access to natural terpenoids with this stereochemistry, as well as to non-natural analogues.
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Affiliation(s)
- Sara P Morcillo
- Department of Organic Chemistry and ‡Department of Inorganic Chemistry, Faculty of Sciences, University of Granada , C. U. Fuentenueva s/n, 18071 Granada, Spain
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50
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Szostak M, Spain M, Procter DJ. On the role of pre- and post-electron-transfer steps in the SmI2 /amine/H(2)O-mediated reduction of esters: new mechanistic insights and kinetic studies. Chemistry 2014; 20:4222-6. [PMID: 24615806 PMCID: PMC4497321 DOI: 10.1002/chem.201400295] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Indexed: 02/02/2023]
Abstract
The mechanism of the SmI2 -mediated reduction of unactivated esters has been studied using a combination of kinetic, radical clocks and reactivity experiments. The kinetic data indicate that all reaction components (SmI2 , amine, H2 O) are involved in the rate equation and that electron transfer is facilitated by Brønsted base assisted deprotonation of water in the transition state. The use of validated cyclopropyl-containing radical clocks demonstrates that the reaction occurs via fast, reversible first electron transfer, and that the electron transfer from simple Sm(II) complexes to aliphatic esters is rapid. Notably, the mechanistic details presented herein indicate that complexation between SmI2 , H2 O and amines affords a new class of structurally diverse, thermodynamically powerful reductants for efficient electron transfer to carboxylic acid derivatives as an attractive alternative to the classical hydride-mediated reductions and as a source of acyl-radical equivalents for CC bond forming processes.
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Affiliation(s)
- Michal Szostak
- School of Chemistry, University of ManchesterOxford Road, Manchester M13 9PL (UK), Fax: (+44) 161-275-4939
| | - Malcolm Spain
- School of Chemistry, University of ManchesterOxford Road, Manchester M13 9PL (UK), Fax: (+44) 161-275-4939
| | - David J Procter
- School of Chemistry, University of ManchesterOxford Road, Manchester M13 9PL (UK), Fax: (+44) 161-275-4939
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