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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Deng Y, Hu Z, Xue J, Yin J, Zhu T, Liu S. Visible-Light-Promoted α-C(sp 3)-H Amination of Ethers with Azoles and Amides. Org Lett 2024; 26:933-938. [PMID: 38241172 DOI: 10.1021/acs.orglett.3c04291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2024]
Abstract
A visible-light-induced highly efficient C(sp3)-H amination of ethers with amides and azoles has been presented under mild conditions via a nitrogen- and carbon-centered radical coupling process. This protocol successfully utilizes 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and tert-butyl nitrite (TBN) as cocatalysts to deliver the aminated products of ethers under aerobic conditions. Notably, the developed reaction features the corresponding products in good yields (up to 93%) with a wide substrate scope. The mechanistic study indicates that C-N bond formation proceeds via a direct radical cross-coupling process. Preliminary biological activity analysis indicates that the resulting products have good and selective inhibitory activity on osteosarcoma (OS) cell lines and are promising for use as hits for drug discovery.
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Affiliation(s)
- Yaqi Deng
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai 200062 China
| | - Zongjing Hu
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai 200062 China
| | - Jian Xue
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai 200062 China
| | - Jiabin Yin
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai 200062 China
| | - Tong Zhu
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai 200062 China
| | - Shunying Liu
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University, Shanghai 200062 China
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4
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Ju M, Lu Z, Novaes LFT, Alvarado JIM, Lin S. Frustrated Radical Pairs in Organic Synthesis. J Am Chem Soc 2023; 145:19478-19489. [PMID: 37656899 PMCID: PMC10625356 DOI: 10.1021/jacs.3c07070] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/03/2023]
Abstract
Frustrated radical pairs (FRPs) describe the phenomenon that two distinct radicals─which would otherwise annihilate each other to form a closed-shell covalent adduct─can coexist in solution, owing to steric repulsion or weak bonding association. FRPs are typically formed via spontaneous single-electron transfer between two sterically encumbered precursors─an oxidant and a reductant─under ambient conditions. The two components of a FRP exhibit orthogonal chemical properties and can often act in cooperativity to achieve interesting radical reactivities. Initially observed in the study of traditional frustrated Lewis pairs, FRPs have recently been shown to be capable of homolytically activating various chemical bonds. In this Perspective, we will discuss the discovery of FRPs, their fundamental reactivity in chemical bond activation, and recent developments of their use in synthetic organic chemistry, including in C-H bond functionalization. We anticipate that FRPs will provide new reaction strategies for solving challenging problems in modern organic synthesis.
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Affiliation(s)
| | | | - Luiz F. T. Novaes
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | | | - Song Lin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
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5
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Boekell NG, Bartulovich CO, Maity S, Flowers RA. Accessing Unusual Reactivity through Chelation-Promoted Bond Weakening. Inorg Chem 2023; 62:5040-5045. [PMID: 36912617 DOI: 10.1021/acs.inorgchem.3c00298] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
Abstract
Highly reducing Sm(II) reductants and protic ligands were used as a platform to ascertain the relationship between low-valent metal-protic ligand affinity and degree of ligand X-H bond weakening with the goal of forming potent proton-coupled electron transfer (PCET) reductants. Among the Sm(II)-protic ligand reductant systems investigated, the samarium dibromide N-methylethanolamine (SmBr2-NMEA) reagent system displayed the best combination of metal-ligand affinity and stability against H2 evolution. The use of SmBr2-NMEA afforded the reduction of a range of substrates that are typically recalcitrant to single-electron reduction including alkynes, lactones, and arenes as stable as biphenyl. Moreover, the unique role of NMEA as a chelating ligand for Sm(II) was demonstrated by the reductive cyclization of unactivated esters bearing pendant olefins in contrast to the SmBr2-water-amine system. Finally, the SmBr2-NMEA reagent system was found to reduce substrates analogous to key intermediates in the nitrogen fixation process. These results reveal SmBr2-NMEA to be a powerful reductant for a wide range of challenging substrates and demonstrate the potential for the rational design of PCET reagents with exceptionally weak X-H bonds.
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Affiliation(s)
- 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
| | - Sandeepan Maity
- Department of Chemistry, C. V. Raman Global University, Bhubaneswar, Odisha 752054, India
| | - Robert A Flowers
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
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6
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Yang X, Reijerse EJ, Bhattacharyya K, Leutzsch M, Kochius M, Nöthling N, Busch J, Schnegg A, Auer AA, Cornella J. Radical Activation of N-H and O-H Bonds at Bismuth(II). J Am Chem Soc 2022; 144:16535-16544. [PMID: 36053726 PMCID: PMC9479083 DOI: 10.1021/jacs.2c05882] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The development of unconventional strategies for the activation of ammonia (NH3) and water (H2O) is of capital importance for the advancement of sustainable chemical strategies. Herein we provide the synthesis and characterization of a radical equilibrium complex based on bismuth featuring an extremely weak Bi-O bond, which permits the in situ generation of reactive Bi(II) species. The ensuing organobismuth(II) engages with various amines and alcohols and exerts an unprecedented effect onto the X-H bond, leading to low BDFEX-H. As a result, radical activation of various N-H and O-H bonds─including ammonia and water─occurs in seconds at room temperature, delivering well-defined Bi(III)-amido and -alkoxy complexes. Moreover, we demonstrate that the resulting Bi(III)-N complexes engage in a unique reactivity pattern with the triad of H+, H-, and H• sources, thus providing alternative pathways for main group chemistry.
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Affiliation(s)
- Xiuxiu Yang
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Edward J Reijerse
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | | | - Markus Leutzsch
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Markus Kochius
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Nils Nöthling
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Julia Busch
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Alexander Schnegg
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Alexander A Auer
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Josep Cornella
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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7
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Kim S, Chen PP, Houk KN, Knowles RR. Reversible Homolysis of a Carbon-Carbon σ-Bond Enabled by Complexation-Induced Bond-Weakening. J Am Chem Soc 2022; 144:15488-15496. [PMID: 35994332 PMCID: PMC9671280 DOI: 10.1021/jacs.2c01229] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A case study of catalytic carbon-carbon σ-bond homolysis is presented. The coordination of a redox-active Lewis acid catalyst reduces the bond-dissociation free energies of adjacent carbon-carbon σ-bonds, and this complexation-induced bond-weakening is used to effect reversible carbon-carbon bond homolysis. Stereochemical isomerization of 1,2-disubstituted cyclopropanes was investigated as a model reaction with a ruthenium (III/II) redox couple adopted for bond weakening. Results from our mechanistic investigation into the stereospecificity of the isomerization reaction are consistent with selective complexation-induced carbon-carbon bond homolysis. The ΔG‡ of catalyzed and uncatalyzed reactions were estimated to be 14.4 and 40.0 kcal/mol, respectively with the computational method, (U)PBE0-D3/def2-TZVPP-SMD(toluene)//(U)B3LYP-D3/def2-SVP. We report this work as the first catalytic example where the complexation-induced bond-weakening effect is quantified through transition state analysis.
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Affiliation(s)
- Suhong Kim
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Pan-Pan Chen
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - K. N. Houk
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Robert R. Knowles
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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8
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Almquist CC, Removski N, Rajeshkumar T, Gelfand BS, Maron L, Piers WE. Spontaneous Ammonia Activation Through Coordination-Induced Bond Weakening in Molybdenum Complexes of a Dianionic Pentadentate Ligand Platform. Angew Chem Int Ed Engl 2022; 61:e202203576. [PMID: 35748415 DOI: 10.1002/anie.202203576] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Indexed: 11/10/2022]
Abstract
Ammonia oxidation catalyzed by molecular compounds is of current interest as a carbon-free source of dihydrogen. Activation of N-H bonds through coordination to transition metal centers is a key reaction in this process. We report the substantial activation of ammonia via reaction with low-valent molybdenum complexes of a diborate pentadentate ligand system. Spontaneous loss of dihydrogen from (B2 Pz4 Py)MoII -NH3 at room temperature to produce the dinuclear μ-nitrido compound (B2 Pz4 Py)Mo-N-Mo(B2 Pz4 Py) is observed due to substantial N-H bond weakening upon coordination to Mo. Mechanistic details are supported through the experimental observation/characterization of terminal amido, imido and nitrido complexes and density functional theory computations. The generally under-appreciated role of bridging nitrido intermediates is revealed and discussed, providing guidance for further catalyst development for this process.
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Affiliation(s)
- C Christopher Almquist
- Department of Chemistry, University of Calgary, 2500 University Dr. NW, T2N 1N4, AB, Calgary, Canada
| | - Nicole Removski
- Department of Chemistry, University of Calgary, 2500 University Dr. NW, T2N 1N4, AB, Calgary, Canada
| | - Thayalan Rajeshkumar
- LPCNO, INSA, UPS, Université de Toulouse, 135 avenue de Rangueil, 31077, Toulouse, France
| | - Benjamin S Gelfand
- Department of Chemistry, University of Calgary, 2500 University Dr. NW, T2N 1N4, AB, Calgary, Canada
| | - Laurent Maron
- LPCNO, INSA, UPS, Université de Toulouse, 135 avenue de Rangueil, 31077, Toulouse, France
| | - Warren E Piers
- Department of Chemistry, University of Calgary, 2500 University Dr. NW, T2N 1N4, AB, Calgary, Canada
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9
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Liu L, Zhang Q, Wang C. Redox-Neutral Generation of Iminyl Radicals by N-Heterocyclic Carbene Catalysis: Rapid Access to Phenanthridines from Vinyl Azides. Org Lett 2022; 24:5913-5917. [PMID: 35925779 DOI: 10.1021/acs.orglett.2c02118] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An N-heterocyclic carbene-catalyzed oxidant-, metal- and light-free iminyl radical generation pathway stemming from the reaction of vinyl azide and α-bromo ester is uncovered. This newly developed methodology is successfully applied to the redox-neutral construction of a number of diversified phenanthridine derivatives with nice functional group compatibility. Insights from the mechanism study reveal that this NHC-catalyzed transformation potentially proceeds through an alkyl radical addition-initiated HAS process, with the iminyl radical as an active intermediate.
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Affiliation(s)
- Lixia Liu
- College of Chemistry and Materials Science, Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and Applications, Jinan University, Guangzhou, Guangdong511443, China
| | - Qijing Zhang
- College of Chemistry and Materials Science, Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and Applications, Jinan University, Guangzhou, Guangdong511443, China
| | - Chengming Wang
- College of Chemistry and Materials Science, Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and Applications, Jinan University, Guangzhou, Guangdong511443, China
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10
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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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11
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Wu X, Chang Y, Lin S. Titanium radical redox catalysis: Recent innovations in catalysts, reactions, and modes of activation. Chem 2022; 8:1805-1821. [DOI: 10.1016/j.chempr.2022.06.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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Almquist CC, Removski N, Rajeshkumar T, Gelfand B, Piers W, Maron L. Spontaneous Ammonia Activation Through Coordination Induced Bond Weakening in Molybdenum Complexes of a Dianionic Pentadentate Ligand Platform. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202203576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
| | | | | | | | - Warren Piers
- University of Calgary Department of Chemistry 2500 University Dr. NW T2N 1N4 Calgary CANADA
| | - Laurent Maron
- University of Toulouse 3: Universite Toulouse III Paul Sabatier LPCNO FRANCE
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13
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Liu L, Zhou CY, Wang C. Construction of highly congested quaternary carbon centers by NHC catalysis through dearomatization. GREEN SYNTHESIS AND CATALYSIS 2022. [DOI: 10.1016/j.gresc.2022.05.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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14
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Sakai K, Oisaki K, Kanai M. A Germanium Catalyst Accelerates the Photoredox α-C(sp 3)-H Alkylation of Primary Amines. Org Lett 2022; 24:3325-3330. [PMID: 35486160 DOI: 10.1021/acs.orglett.2c00871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Site-selective C(sp3)-H functionalizations using photoredox catalysis (PC) and hydrogen atom transfer (HAT) catalysis have received increasing attention. Here, we report a Ph2GeCl2 cocatalyst that greatly improves the yield of α-C(sp3)-H alkylation of primary amines catalyzed by a PC-HAT hybrid system. The α-position of the amino group selectively reacted even when weaker C-H bonds existed in the substrates. This finding may help the design of a novel site-selective hybrid catalysis.
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Affiliation(s)
- Kentaro Sakai
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Kounosuke Oisaki
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Motomu Kanai
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
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15
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Salaverri N, Carli B, Díaz-Tendero S, Marzo L, Alemán J. Enantioselective Addition of Remote Alkyl Radicals to Double Bonds by Photocatalytic Proton-Coupled Electron Transfer (PCET) Deconstruction of Unstrained Cycloalkanols. Org Lett 2022; 24:3123-3127. [PMID: 35362991 PMCID: PMC9087350 DOI: 10.1021/acs.orglett.2c00662] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Herein, we report
the enantioselective addition of remote alkyl
radicals, generated from the ring opening of unstrained cycloalkanols
by a proton-coupled electron transfer (PCET) process, to 2-acyl imidazoles
previously coordinated to a rhodium-based chiral Lewis acid. High
yields and enantioselectivites up to 99% are achieved in 1 h. Mechanistic
investigations support the formation of the remote alkyl radical by
a PCET process, and theoretical studies explain the observed stereochemistry
in the addition step.
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Affiliation(s)
- Noelia Salaverri
- Departamento de Química Orgánica (Módulo 1), Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
| | - Benedetta Carli
- Departamento de Química Orgánica (Módulo 1), Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
| | - Sergio Díaz-Tendero
- Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, 28049, Madrid, Spain.,Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain.,Departamento de Química (Módulo 13), Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
| | - Leyre Marzo
- Departamento de Química Orgánica (Módulo 1), Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
| | - José Alemán
- Departamento de Química Orgánica (Módulo 1), Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain.,Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, 28049, Madrid, Spain
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16
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Murray PD, Cox JH, Chiappini ND, Roos CB, McLoughlin EA, Hejna BG, Nguyen ST, Ripberger HH, Ganley JM, Tsui E, Shin NY, Koronkiewicz B, Qiu G, Knowles RR. Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis. Chem Rev 2022; 122:2017-2291. [PMID: 34813277 PMCID: PMC8796287 DOI: 10.1021/acs.chemrev.1c00374] [Citation(s) in RCA: 158] [Impact Index Per Article: 79.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Indexed: 12/16/2022]
Abstract
We present here a review of the photochemical and electrochemical applications of multi-site proton-coupled electron transfer (MS-PCET) in organic synthesis. MS-PCETs are redox mechanisms in which both an electron and a proton are exchanged together, often in a concerted elementary step. As such, MS-PCET can function as a non-classical mechanism for homolytic bond activation, providing opportunities to generate synthetically useful free radical intermediates directly from a wide variety of common organic functional groups. We present an introduction to MS-PCET and a practitioner's guide to reaction design, with an emphasis on the unique energetic and selectivity features that are characteristic of this reaction class. We then present chapters on oxidative N-H, O-H, S-H, and C-H bond homolysis methods, for the generation of the corresponding neutral radical species. Then, chapters for reductive PCET activations involving carbonyl, imine, other X═Y π-systems, and heteroarenes, where neutral ketyl, α-amino, and heteroarene-derived radicals can be generated. Finally, we present chapters on the applications of MS-PCET in asymmetric catalysis and in materials and device applications. Within each chapter, we subdivide by the functional group undergoing homolysis, and thereafter by the type of transformation being promoted. Methods published prior to the end of December 2020 are presented.
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Affiliation(s)
- Philip
R. D. Murray
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - James H. Cox
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Nicholas D. Chiappini
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Casey B. Roos
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | | | - Benjamin G. Hejna
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Suong T. Nguyen
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Hunter H. Ripberger
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Jacob M. Ganley
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Elaine Tsui
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Nick Y. Shin
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Brian Koronkiewicz
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Guanqi Qiu
- 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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17
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18
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Avilés A, Colmenares F. Exploring the potential of the ammine complexes M(NH 3) n+ (M = Zr, Re) to activate NH 3. NEW J CHEM 2022. [DOI: 10.1039/d1nj05386h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
NH3 is activated by the complex Zr(NH3)7+ through a mechanism involving radical species.
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Affiliation(s)
- Alejandro Avilés
- Departamento de Física y Química Teórica, Facultad de Química, Universidad Nacional Autónoma de México, CDMX 04510, Mexico
| | - Fernando Colmenares
- Departamento de Física y Química Teórica, Facultad de Química, Universidad Nacional Autónoma de México, CDMX 04510, Mexico
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19
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Agarwal RG, Coste SC, Groff BD, Heuer AM, Noh H, Parada GA, Wise CF, Nichols EM, Warren JJ, Mayer JM. Free Energies of Proton-Coupled Electron Transfer Reagents and Their Applications. Chem Rev 2021; 122:1-49. [PMID: 34928136 DOI: 10.1021/acs.chemrev.1c00521] [Citation(s) in RCA: 134] [Impact Index Per Article: 44.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We present an update and revision to our 2010 review on the topic of proton-coupled electron transfer (PCET) reagent thermochemistry. Over the past decade, the data and thermochemical formalisms presented in that review have been of value to multiple fields. Concurrently, there have been advances in the thermochemical cycles and experimental methods used to measure these values. This Review (i) summarizes those advancements, (ii) corrects systematic errors in our prior review that shifted many of the absolute values in the tabulated data, (iii) provides updated tables of thermochemical values, and (iv) discusses new conclusions and opportunities from the assembled data and associated techniques. We advocate for updated thermochemical cycles that provide greater clarity and reduce experimental barriers to the calculation and measurement of Gibbs free energies for the conversion of X to XHn in PCET reactions. In particular, we demonstrate the utility and generality of reporting potentials of hydrogenation, E°(V vs H2), in almost any solvent and how these values are connected to more widely reported bond dissociation free energies (BDFEs). The tabulated data demonstrate that E°(V vs H2) and BDFEs are generally insensitive to the nature of the solvent and, in some cases, even to the phase (gas versus solution). This Review also presents introductions to several emerging fields in PCET thermochemistry to give readers windows into the diversity of research being performed. Some of the next frontiers in this rapidly growing field are coordination-induced bond weakening, PCET in novel solvent environments, and reactions at material interfaces.
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Affiliation(s)
- Rishi G Agarwal
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Scott C Coste
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Benjamin D Groff
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Abigail M Heuer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Hyunho Noh
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Giovanny A Parada
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States.,Department of Chemistry, The College of New Jersey, Ewing, New Jersey 08628, United States
| | - Catherine F Wise
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Eva M Nichols
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Jeffrey J Warren
- Department of Chemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - James M Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
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20
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Jiang Y, Wang Q, Zhang X, Koh MJ. Synthesis of C-glycosides by Ti-catalyzed stereoselective glycosyl radical functionalization. Chem 2021. [DOI: 10.1016/j.chempr.2021.09.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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21
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N-heterocyclic carbene-catalyzed intramolecular aza-Michael addition of alkyl amines to α,β-unsaturated carboxylic acid: Synthesis of pyrrolidines and piperidines. Tetrahedron 2021. [DOI: 10.1016/j.tet.2021.132337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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22
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Wong A, Chakraborty A, Bawari D, Wu G, Dobrovetsky R, Ménard G. Facile proton-coupled electron transfer enabled by coordination-induced E-H bond weakening to boron. Chem Commun (Camb) 2021; 57:6903-6906. [PMID: 34151918 DOI: 10.1039/d1cc02832d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the facile activation of aryl E-H (ArEH; E = N, O, S; Ar = Ph or C6F5) or ammonia N-H bonds via coordination-induced bond weakening to a redox-active boron center in the complex, (1-). Substantial decreases in E-H bond dissociation free energies (BDFEs) are observed upon substrate coordination, enabling subsequent facile proton-coupled electron transfer (PCET). A drop of >50 kcal mol-1 in H2N-H BDFE upon coordination was experimentally determined.
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Affiliation(s)
- Anthony Wong
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA.
| | - Arunavo Chakraborty
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA.
| | - Deependra Bawari
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Guang Wu
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA.
| | - Roman Dobrovetsky
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Gabriel Ménard
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA.
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23
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Wang Z, Johnson SI, Wu G, Ménard G. Multiple N-H and C-H Hydrogen Atom Abstractions Through Coordination-Induced Bond Weakening at Fe-Amine Complexes. Inorg Chem 2021; 60:8242-8251. [PMID: 34011142 DOI: 10.1021/acs.inorgchem.1c00923] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the use of the reported Fe-phthalocyanine complex, PcFe (1; Pc = 1,4,8,11,15,18,22,25-octaethoxy-phthalocyanine), to generate PcFe-amine complexes 1-(NH3)2, 1-(MeNH2)2, and 1-(Me2NH)2. Treatment of 1 or 1-(NH3)2 to an excess of the stable aryloxide radical, 2,4,6-tritert-butylphenoxyl radical (tBuArO•), under NH3 resulted in catalytic H atom abstraction (HAA) and C-N coupling to generate the product 4-amino-2,4,6-tritert-butylcyclohexa-2,5-dien-1-one (2) and tBuArOH. Exposing 1-(NH3)2 to an excess of the trityl (CPh3) variant, 2,6-di-tert-butyl-4-tritylphenoxyl radical (TrArO•), under NH3 did not lead to catalytic ammonia oxidation as previously reported in a related Ru-porphyrin complex. However, pronounced coordination-induced bond weakening of both α N-H and β C-H in the alkylamine congeners, 1-(MeNH2)2 and 1-(Me2NH)2, led to multiple HAA events yielding the unsaturated cyanide complex, 1-(MeNH2)(CN), and imine complex, 1-(MeN═CH2)2, respectively. Subsequent C-N bond formation was also observed in the latter upon addition of a coordinating ligand. Detailed computational studies support an alternating mechanism involving sequential N-H and C-H HAA to generate these unsaturated products.
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Affiliation(s)
- Zongheng Wang
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Samantha I Johnson
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Guang Wu
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Gabriel Ménard
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
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24
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Yue WJ, Day CS, Martin R. Site-Selective Defluorinative sp3 C–H Alkylation of Secondary Amides. J Am Chem Soc 2021; 143:6395-6400. [DOI: 10.1021/jacs.1c03126] [Citation(s) in RCA: 73] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Wen-Jun Yue
- The Barcelona Institute of Science and Technology, Institute of Chemical Research of Catalonia (ICIQ), Av. Països Catalans 16, 43007 Tarragona, Spain
- Departament de Química Analítica i Química Orgànica, Universitat Rovira i Virgili, c/Marcel·lí Domingo, 1, 43007 Tarragona, Spain
| | - Craig S. Day
- The Barcelona Institute of Science and Technology, Institute of Chemical Research of Catalonia (ICIQ), Av. Països Catalans 16, 43007 Tarragona, Spain
- Departament de Química Analítica i Química Orgànica, Universitat Rovira i Virgili, c/Marcel·lí Domingo, 1, 43007 Tarragona, Spain
| | - Ruben Martin
- The Barcelona Institute of Science and Technology, Institute of Chemical Research of Catalonia (ICIQ), Av. Països Catalans 16, 43007 Tarragona, Spain
- ICREA, Passeig Lluís Companys, 23, 08010, Barcelona, Spain
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25
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Zhou Z, Kong X, Liu T. Applications of Proton-Coupled Electron Transfer in Organic Synthesis. CHINESE J ORG CHEM 2021. [DOI: 10.6023/cjoc202106001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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26
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Avilés A, Torres AE, Colmenares F. Low‐Energy Pathways Found for the NH
3
Activation and H
2
Elimination by the Werner‐Type Complexes M(NH
3
)
4
+
(M=Fe, Ru and Os). ChemistrySelect 2020. [DOI: 10.1002/slct.202003816] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Alejandro Avilés
- Departamento de Física y Química Teórica Facultad de Química Universidad Nacional Autónoma de México México CDMX. 04510 Mexico
| | - Ana E. Torres
- Departamento de Micro y Nanotecnologías Instituto de Ciencias Aplicadas y Tecnología Universidad Nacional Autónoma de México México CDMX. 04510 Mexico
| | - Fernando Colmenares
- Departamento de Física y Química Teórica Facultad de Química Universidad Nacional Autónoma de México México CDMX. 04510 Mexico
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27
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Sharma S, Roy A, Shaw K, Bisai A, Paul A. Electrochemical Synthesis of Dimeric 2-Oxindole Sharing Vicinal Quaternary Centers Employing Proton-Coupled Electron Transfer. J Org Chem 2020; 85:14926-14936. [DOI: 10.1021/acs.joc.0c01621] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Sulekha Sharma
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462 066, India
| | - Avishek Roy
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462 066, India
| | - Kundan Shaw
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462 066, India
| | - Alakesh Bisai
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462 066, India
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, Nadia, West Bengal 741 246, India
| | - Amit Paul
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462 066, India
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28
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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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29
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Elliott Q, Dos Passos Gomes G, Evoniuk CJ, Alabugin IV. Testing the limits of radical-anionic CH-amination: a 10-million-fold decrease in basicity opens a new path to hydroxyisoindolines via a mixed C-N/C-O-forming cascade. Chem Sci 2020; 11:6539-6555. [PMID: 34094120 PMCID: PMC8159354 DOI: 10.1039/c9sc06511c] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 02/14/2020] [Indexed: 11/21/2022] Open
Abstract
An intramolecular C(sp3)-H amidation proceeds in the presence of t-BuOK, molecular oxygen, and DMF. This transformation is initiated by the deprotonation of an acidic N-H bond and selective radical activation of a benzylic C-H bond towards hydrogen atom transfer (HAT). Cyclization of this radical-anion intermediate en route to a two-centered/three-electron (2c,3e) C-N bond removes electron density from nitrogen. As this electronegative element resists such an "oxidation", making nitrogen more electron rich is key to overcoming this problem. This work dramatically expands the range of N-anions that can participate in this process by using amides instead of anilines. The resulting 107-fold decrease in the N-component basicity (and nucleophilicity) doubles the activation barrier for C-N bond formation and makes this process nearly thermoneutral. Remarkably, this reaction also converts a weak reductant into a much stronger reductant. Such "reductant upconversion" allows mild oxidants like molecular oxygen to complete the first part of the cascade. In contrast, the second stage of NH/CH activation forms a highly stabilized radical-anion intermediate incapable of undergoing electron transfer to oxygen. Because the oxidation is unfavored, an alternative reaction path opens via coupling between the radical anion intermediate and either superoxide or hydroperoxide radical. The hydroperoxide intermediate transforms into the final hydroxyisoindoline products under basic conditions. The use of TEMPO as an additive was found to activate less reactive amides. The combination of experimental and computational data outlines a conceptually new mechanism for conversion of unprotected amides into hydroxyisoindolines proceeding as a sequence of C-H amidation and C-H oxidation.
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Affiliation(s)
- Quintin Elliott
- Department of Chemistry and Biochemistry, Florida State University Tallahassee Florida 32306 USA
| | - Gabriel Dos Passos Gomes
- Department of Chemistry and Biochemistry, Florida State University Tallahassee Florida 32306 USA
| | - Christopher J Evoniuk
- Department of Chemistry and Biochemistry, Florida State University Tallahassee Florida 32306 USA
| | - Igor V Alabugin
- Department of Chemistry and Biochemistry, Florida State University Tallahassee Florida 32306 USA
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30
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Sakai K, Oisaki K, Kanai M. Identification of Bond‐Weakening Spirosilane Catalyst for Photoredox α‐C−H Alkylation of Alcohols. Adv Synth Catal 2019. [DOI: 10.1002/adsc.201901253] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Kentaro Sakai
- Graduate School of Pharmaceutical SciencesThe University of Tokyo 7-3-1, Hongo, Bunkyo-ku Tokyo 113-0033 Japan
| | - Kounosuke Oisaki
- Graduate School of Pharmaceutical SciencesThe University of Tokyo 7-3-1, Hongo, Bunkyo-ku Tokyo 113-0033 Japan
| | - Motomu Kanai
- Graduate School of Pharmaceutical SciencesThe University of Tokyo 7-3-1, Hongo, Bunkyo-ku Tokyo 113-0033 Japan
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31
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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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32
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Abstract
New catalytic strategies that leverage single-electron redox events have provided chemists with useful tools for solving synthetic problems. In this context, Ti offers opportunities that are complementary to late transition metals for reaction discovery. Following foundational work on epoxide reductive functionalization, recent methodological advances have significantly expanded the repertoire of Ti radical chemistry. This Synopsis summarizes recent developments in the burgeoning area of Ti radical catalysis with a focus on innovative catalytic strategies such as radical redox-relay and dual catalysis.
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Affiliation(s)
- Terry McCallum
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
| | - Xiangyu Wu
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
| | - Song Lin
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
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33
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Ramírez-Solís A, Bartulovich CO, León-Pimentel CI, Saint-Martin H, Anderson WR, Flowers RA. Experimental and Theoretical Studies on the Aqueous Solvation and Reactivity of SmCl2 and Comparison with SmBr2 and SmI2. Inorg Chem 2019; 58:13927-13932. [DOI: 10.1021/acs.inorgchem.9b01818] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Alejandro Ramírez-Solís
- Departamento de Física, Centro de Investigación en Ciencias-IICBA Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos 62209, Mexico
| | | | | | | | - William R. Anderson
- 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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34
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Mannisto JK, Sahari A, Lagerblom K, Niemi T, Nieger M, Sztanó G, Repo T. One‐Step Synthesis of 3,4‐Disubstituted 2‐Oxazolidinones by Base‐Catalyzed CO
2
Fixation and Aza‐Michael Addition. Chemistry 2019; 25:10284-10289. [DOI: 10.1002/chem.201902451] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Indexed: 12/11/2022]
Affiliation(s)
- Jere K. Mannisto
- Department of ChemistryUniversity of Helsinki, P.O. Box 55 A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Aleksi Sahari
- Department of ChemistryUniversity of Helsinki, P.O. Box 55 A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Kalle Lagerblom
- Department of ChemistryUniversity of Helsinki, P.O. Box 55 A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Teemu Niemi
- Department of ChemistryUniversity of Helsinki, P.O. Box 55 A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Martin Nieger
- Department of ChemistryUniversity of Helsinki, P.O. Box 55 A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Gábor Sztanó
- Department of ChemistryUniversity of Helsinki, P.O. Box 55 A.I. Virtasen aukio 1 00014 Helsinki Finland
| | - Timo Repo
- Department of ChemistryUniversity of Helsinki, P.O. Box 55 A.I. Virtasen aukio 1 00014 Helsinki Finland
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35
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Ye KY, McCallum T, Lin S. Bimetallic Radical Redox-Relay Catalysis for the Isomerization of Epoxides to Allylic Alcohols. J Am Chem Soc 2019; 141:9548-9554. [PMID: 31180216 DOI: 10.1021/jacs.9b04993] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Organic radicals are generally short-lived intermediates with exceptionally high reactivity. Strategically, achieving synthetically useful transformations mediated by organic radicals requires both efficient initiation and selective termination events. Here, we report a new catalytic strategy, namely, bimetallic radical redox-relay, in the regio- and stereoselective rearrangement of epoxides to allylic alcohols. This approach exploits the rich redox chemistry of Ti and Co complexes and merges reductive epoxide ring opening (initiation) with hydrogen atom transfer (termination). Critically, upon effecting key bond-forming and -breaking events, Ti and Co catalysts undergo proton transfer/electron transfer with one another to achieve turnover, thus constituting a truly synergistic dual catalytic system.
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Affiliation(s)
- Ke-Yin Ye
- College of Chemistry , Fuzhou University , Fuzhou , 350116 , P.R. China.,Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
| | - Terry McCallum
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
| | - Song Lin
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
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36
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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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37
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Kadassery KJ, Sethi K, Fanara PM, Lacy DC. CO-Photolysis-Induced H-Atom Transfer from MnIO–H Bonds. Inorg Chem 2019; 58:4679-4685. [DOI: 10.1021/acs.inorgchem.9b00322] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Karthika J. Kadassery
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - Komal Sethi
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - Paul M. Fanara
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - David C. Lacy
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
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38
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Wang L, Yang Z, Zhu H, Liu H, Lv S, Xu Y. TEMPO and Silver-Mediated Intermolecular Phosphonylation of Alkenes: Stereoselective Synthesis of ( E
)-Alkenylphosphonates. European J Org Chem 2019. [DOI: 10.1002/ejoc.201801678] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Lei Wang
- Institute of Medicinal Plant Development; Chinese Academy of Medical Science and Peking Union Medical College; 100193 Beijing P. R. China
| | - Zhen Yang
- Institute of Medicinal Plant Development; Chinese Academy of Medical Science and Peking Union Medical College; 100193 Beijing P. R. China
- Jilin Academy of Traditional Chinese Medical Science; 130021 Changchun China
| | - Huijuan Zhu
- Institute of Medicinal Plant Development; Chinese Academy of Medical Science and Peking Union Medical College; 100193 Beijing P. R. China
| | - Haitao Liu
- Institute of Medicinal Plant Development; Chinese Academy of Medical Science and Peking Union Medical College; 100193 Beijing P. R. China
| | - Shuaipeng Lv
- Institute of Medicinal Plant Development; Chinese Academy of Medical Science and Peking Union Medical College; 100193 Beijing P. R. China
| | - Yue Xu
- Institute of Medicinal Plant Development; Chinese Academy of Medical Science and Peking Union Medical College; 100193 Beijing P. R. China
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39
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Chang MC, Jesse KA, Filatov AS, Anderson JS. Reversible homolytic activation of water via metal-ligand cooperativity in a T-shaped Ni(ii) complex. Chem Sci 2019; 10:1360-1367. [PMID: 30809351 PMCID: PMC6354739 DOI: 10.1039/c8sc03719a] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 11/05/2018] [Indexed: 12/18/2022] Open
Abstract
A T-shaped Ni(ii) complex [Tol,PhDHPy]Ni has been prepared and characterized. EPR spectra and DFT calculations of this complex suggest that the electronic structure is best described as a high-spin Ni(ii) center antiferromagnetically coupled with a ligand-based radical. This complex reacts with water at room temperature to generate the dimeric complex [Tol,PhDHPy]Ni(μ-OH)Ni[Tol,PhDHPyH] which has been thoroughly characterized by SXRD, NMR, IR and deuterium-labeling experiments. Addition of simple ligands such as phosphines or pyridine displaces water and demonstrates the reversibility of water activation in this system. The water activation step has been examined by kinetic studies and DFT calculations which suggest an unusual homolytic reaction via a bimetallic mechanism. The ΔH ‡, ΔS ‡ and KIE (k H/k D) of the reaction are 5.5 kcal mol-1, -23.8 cal mol-1 K-1, and 2.4(1), respectively. In addition to the reversibility of water addition, this system is capable of activating water towards net O-atom transfer to substrates such as aromatic C-H bonds and phosphines. This reactivity is facilitated by the ability of the dihydrazonopyrrole ligand to accept H-atoms and illustrates the utility of metal ligand cooperation in activating O-H bonds with high bond dissociation energies.
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Affiliation(s)
- Mu-Chieh Chang
- Department of Chemistry , The University of Chicago , Chicago , Illinois 60637 , USA .
| | - Kate A Jesse
- Department of Chemistry , The University of Chicago , Chicago , Illinois 60637 , USA .
| | - Alexander S Filatov
- Department of Chemistry , The University of Chicago , Chicago , Illinois 60637 , USA .
| | - John S Anderson
- Department of Chemistry , The University of Chicago , Chicago , Illinois 60637 , USA .
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40
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Leijendekker LH, Weweler J, Leuther TM, Kratzert D, Streuff J. Development, Scope, and Applications of Titanium(III)-Catalyzed Cyclizations to Aminated N-Heterocycles. Chemistry 2019; 25:3382-3390. [PMID: 30615817 DOI: 10.1002/chem.201805909] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Indexed: 01/30/2023]
Affiliation(s)
- Leonardus H. Leijendekker
- Institut für Organische Chemie; Albert-Ludwigs-Universität Freiburg; Albertstr. 21 79104 Freiburg im Breisgau Germany
| | - Jens Weweler
- Institut für Organische Chemie; Albert-Ludwigs-Universität Freiburg; Albertstr. 21 79104 Freiburg im Breisgau Germany
| | - Tobias M. Leuther
- Institut für Organische Chemie; Albert-Ludwigs-Universität Freiburg; Albertstr. 21 79104 Freiburg im Breisgau Germany
| | - Daniel Kratzert
- Institut für Anorganische und Analytische Chemie; Albert-Ludwigs-Universität Freiburg; Albertstr. 21 79104 Freiburg im Breisgau Germany
| | - Jan Streuff
- Institut für Organische Chemie; Albert-Ludwigs-Universität Freiburg; Albertstr. 21 79104 Freiburg im Breisgau Germany
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41
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Siu JC, Parry JB, Lin S. Aminoxyl-Catalyzed Electrochemical Diazidation of Alkenes Mediated by a Metastable Charge-Transfer Complex. J Am Chem Soc 2019; 141:2825-2831. [PMID: 30673216 DOI: 10.1021/jacs.8b13192] [Citation(s) in RCA: 104] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
We report the development of a new aminoxyl radical catalyst, CHAMPO, for the electrochemical diazidation of alkenes. Mediated by an anodically generated charge-transfer complex in the form of CHAMPO-N3, radical diazidation was achieved across a broad scope of alkenes without the need for a transition metal catalyst or a chemical oxidant. Mechanistic data support a dual catalytic role for the aminoxyl serving as both a single-electron oxidant and a radical group transfer agent.
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Affiliation(s)
- Juno C Siu
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
| | - Joseph B Parry
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
| | - Song Lin
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
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42
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Tadokoro M, Isogai K, Harada S, Kouchi T, Yamane T, Sugaya T, Kamebuchi H. Evidence of proton-coupled mixed-valency by electrochemical behavior on transition metal complex dimers bridged by two Ag + ions. Dalton Trans 2019; 48:535-546. [PMID: 30525138 DOI: 10.1039/c8dt03962c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
H-Bonded metal complex dimers with reversible redox behaviour, which are connected by a low-barrier hydrogen bond (LBHB) with a very low energy barrier for proton transfer, can provide a unique mixed-valency state stabilized by the proton-coupled electron transfer (PCET) phenomenon. Using cyclic voltammetry measurements, newly prepared [ReIIICl2(PnPr3)2(Hbim)]2 (2) and [OsIIICl2(PnPr3)2(Hbim)]2 (3) existing as H-bonded dimers in a CH2Cl2 solution showed a four-step and four-electron transfer containing two mixed-valency states of ReIIReIII and ReIIIReIV, and OsIIOsIII and OsIIIOsVI, respectively. Furthermore, [ReIIICl2(PnPr3)2(Agbim)]2 (4) and [OsIIICl2(PnPr3)2(Agbim)]2 (5), bridged by two Ag+ ions instead of two H-bonding protons, were prepared, and their electrochemical behaviours changed to a two-step and four-electron transfer. It is clear that the H-bonded complex dimers 2 and 3, connected by an LBHB, can be electrochemically stabilized into unique pairs of mixed-valency states by PCET, and the H-bonding proton transfer also controls the electrochemical redox behaviour.
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Affiliation(s)
- Makoto Tadokoro
- Tokyo University of Science, Faculty of Science, Department of Chemistry, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan.
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43
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Resa S, Millán A, Fuentes N, Crovetto L, Luisa Marcos M, Lezama L, Choquesillo-Lazarte D, Blanco V, Campaña AG, Cárdenas DJ, Cuerva JM. O–H and (CO)N–H bond weakening by coordination to Fe(ii). Dalton Trans 2019; 48:2179-2189. [DOI: 10.1039/c8dt04689a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Coordination of hydroxyl/amide groups to Fe(ii) diminishes BDFEs of O–H and (CO)N–H bonds down to 76.0 and 80.5 kcal mol−1 respectively.
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44
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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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45
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Luu HT, Streuff J. Development of an Efficient Synthesis of rac
-3-Demethoxyerythratidinone via a Titanium(III) Catalyzed Imine-Nitrile Coupling. European J Org Chem 2018. [DOI: 10.1002/ejoc.201801479] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Hieu-Trinh Luu
- Institut für Organische Chemie; Albert-Ludwigs-Universität Freiburg; Albertstraße 21 79104 Freiburg im Breisgau Germany
| | - Jan Streuff
- Institut für Organische Chemie; Albert-Ludwigs-Universität Freiburg; Albertstraße 21 79104 Freiburg im Breisgau Germany
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46
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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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47
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Ramírez-Solís A, Bartulovich CO, Chciuk TV, Hernández-Cobos J, Saint-Martin H, Maron L, Anderson WR, Li AM, Flowers RA. Experimental and Theoretical Studies on the Implications of Halide-Dependent Aqueous Solvation of Sm(II). J Am Chem Soc 2018; 140:16731-16739. [DOI: 10.1021/jacs.8b09857] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Alejandro Ramírez-Solís
- Departamento de Física, Centro de Investigación en Ciencias-IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos 62209 México
| | | | - Tesia V. Chciuk
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Jorge Hernández-Cobos
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Humberto Saint-Martin
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Laurent Maron
- Laboratoire de Physique et Chimie de Nano-objets, Université de Toulouse, INSA-CNRS-UPS, 135, Avenue de Rangueil, 31077 Toulouse, France
| | - William R. Anderson
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Anna M. Li
- 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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48
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McDonald BR, Scheidt KA. Intermolecular Reductive Couplings of Arylidene Malonates via Lewis Acid/Photoredox Cooperative Catalysis. Org Lett 2018; 20:6877-6881. [PMID: 30346177 DOI: 10.1021/acs.orglett.8b02893] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A cooperative Lewis acid/photocatalytic reduction of arylidene malonates yields a versatile radical anion species. This intermediate preferentially undergoes intermolecular radical-radical coupling reactions, and not the conjugate addition-dimerization reactivity typically observed in the single-electron reduction of conjugate acceptors. Reported here is the development of this open-shell species in intermolecular radical-radical cross couplings, radical dimerizations, and transfer hydrogenations. This reactivity underscores the enabling modularity of cooperative catalysis and demonstrates the utility of stabilized enoate-derived radical anions in intermolecular bond forming reactions.
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Affiliation(s)
- Benjamin R McDonald
- Department of Chemistry, Center for Molecular Innovation and Drug Discovery , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , United States
| | - Karl A Scheidt
- Department of Chemistry, Center for Molecular Innovation and Drug Discovery , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , United States
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49
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Bezdek MJ, Chirik PJ. Proton-Coupled Electron Transfer to a Molybdenum Ethylene Complex Yields a β-Agostic Ethyl: Structure, Dynamics and Mechanism. J Am Chem Soc 2018; 140:13817-13826. [DOI: 10.1021/jacs.8b08460] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Máté J. Bezdek
- 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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50
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Suga T, Shimazu S, Ukaji Y. Low-Valent Titanium-Mediated Radical Conjugate Addition Using Benzyl Alcohols as Benzyl Radical Sources. Org Lett 2018; 20:5389-5392. [DOI: 10.1021/acs.orglett.8b02305] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Takuya Suga
- Division of Material Chemistry, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan
| | - Shoma Shimazu
- Division of Material Chemistry, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan
| | - Yutaka Ukaji
- Division of Material Chemistry, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan
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