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Helou de Oliveira PH, Boaler PJ, Hua G, West NM, Hembre RT, Penney JM, Al-Afyouni MH, Woollins JD, García-Domínguez A, Lloyd-Jones GC. Kinetics of sulfur-transfer from titanocene (poly)sulfides to sulfenyl chlorides: rapid metal-assisted concerted substitution. Chem Sci 2024; 15:11875-11883. [PMID: 39092120 PMCID: PMC11290412 DOI: 10.1039/d4sc02737j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 06/16/2024] [Indexed: 08/04/2024] Open
Abstract
The kinetics of sulfur transfer from titanocene (poly)sulfides (RCp2TiS5, Cp2TiS4CMe2, Cp2Ti(SAr)2, Cp2TiCl(SAr)) to sulfenyl chlorides (S2Cl2, RSCl) have been investigated by a combination of stopped-flow UV-Vis/NMR reaction monitoring, titration assays, numerical kinetic modelling and KS-DFT calculations. The reactions are rapid, proceeding to completion over timescales of milliseconds to minutes, via a sequence of two S-S bond-forming steps (k 1, k 2). The archetypical polysulfides Cp2TiS5 (1a) and Cp2TiS4C(Me2) (2a) react with disulfur dichloride (S2Cl2) through rate-limiting intermolecular S-S bond formation (k 1) followed by a rapid intramolecular cyclization (k 2, with k 2 ≫ k 1 [RSCl]). The monofunctional sulfenyl chlorides (RSCl) studied herein react in two intermolecular S-S bond forming steps proceeding at similar rates (k 1 ≈ k 2). Reactions of titanocene bisthiophenolates, Cp2Ti(SAr)2 (5), with both mono- and di-functional sulfenyl chlorides result in rapid accumulation of the monothiophenolate, Cp2TiCl(SAr) (6) (k 1 > k 2). Across the range of reactants studied, the rates are relatively insensitive to changes in temperature and in the electronics of the sulfenyl chloride, moderately sensitive to the electronics of the titanocene (poly)sulfide (ρ (Ti-(SAr)) ≈ -2.0), and highly sensitive to the solvent polarity, with non-polar solvents (CS2, CCl4) leading to the slowest rates. The combined sensitivities are the result of a concerted, polarized and late transition state for the rate-limiting S-S bond forming step, accompanied by a large entropic penalty. Each substitution step {[Ti]-SR' + Cl-SR → [Ti]-Cl + RS-SR'} proceeds via titanium-assisted Cl-S cleavage to generate a transient pentacoordinate complex, Cl-[Cp2TiX]-S(R')-SR, which then undergoes rapid Ti-S dissociation.
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Affiliation(s)
| | - Patrick J Boaler
- School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
| | - Guoxiong Hua
- School of Chemistry, University of St Andrews North Haugh, St Andrews KY16 9ST UK
| | - Nathan M West
- Eastman Chemical Company 200 S Wilcox Dr Kingsport Tennessee 37660 USA
| | - Robert T Hembre
- Eastman Chemical Company 200 S Wilcox Dr Kingsport Tennessee 37660 USA
| | | | | | | | | | - Guy C Lloyd-Jones
- School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
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2
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Xie H, Breit B. Nickel-Catalyzed Regioselective Hydrothiolation of Allenes Enabled by Visible-Light Photoredox Catalysis. Org Lett 2024; 26:4438-4442. [PMID: 38767303 DOI: 10.1021/acs.orglett.4c01027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Hydrothiolation presents an attractive way to transform allenes into allylic thioethers. Herein, we described an efficient visible-light photoredox-promoted nickel-catalyzed hydrothiolation of allenes with functionalized aromatic and aliphatic thiols. This synergistic catalytic system exhibits unprecedentedly high reactivities and regiocontrol for the construction of allylic thioethers, representing the unique synthetic utility of the earth-abundant Ni-catalyzed method compared with the related noble-metal-catalyzed allylation reactions.
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Affiliation(s)
- Hui Xie
- Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104 Freiburg im Breisgau, Germany
| | - Bernhard Breit
- Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104 Freiburg im Breisgau, Germany
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3
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Hooper RX, Mercado BQ, Holland PL. Desulfurization and N 2 Binding at an Iron Complex Derived from the C-S Activation of Benzothiophene. Organometallics 2023; 42:2019-2027. [PMID: 38282963 PMCID: PMC10810089 DOI: 10.1021/acs.organomet.3c00220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2024]
Abstract
Metal insertion into the C-S bonds of thiophenes is a facile route to interesting polydentate ligand scaffolds with C and S donors. Here, we describe iron-mediated C-S activation of a diphenylphosphine-functionalized benzothiophene proligand. Metalation of the proligand with "tetrakis(trimethylphosphine)iron" gives an initial five-coordinate, diamagnetic iron(II) species with two PMe3 ligands and a dianionic PCS pincer ligand. Upon one-electron reduction, a reactive anionic iron(I) complex is formed. This species then undergoes deep-seated changes, notably cleavage of C-S and C-P bonds in the supporting ligand. Substantial coordination sphere alterations accompany the ligand C-S bond activation, including loss of a sulfur anion from the S-Fe-C metallacycle and reorganization of the two PMe3 ligands. The resulting desulfurized six-coordinate PCC iron complex also has an N2 ligand trans to the vinyl C. Reducing this complex then cleaves a C-P bond in the appended diphenylphosphine, giving a phosphido arm. These ligand transformations demonstrate novel approaches to pincers with thiolates and phosphides, which would be difficult to synthesize using typical methods through free ligand salts.
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Affiliation(s)
- Reagan X. Hooper
- Department of Chemistry, Yale University, New Haven, Connecticut 06520
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4
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Zhao Y, Gao Y, Xie Z, Liao S, Huang J, Huo Y, Chen Q, Li X, Hu XQ. Tf 2O-Promoted Chemoselective C3 Functionalization of Anthranils with Phenols and Thiophenols. J Org Chem 2023. [PMID: 37400425 DOI: 10.1021/acs.joc.3c00722] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2023]
Abstract
Different chemoselectivities of phenols and thiophenols were observed in a Tf2O-promoted C3 functionalization of simple anthranils. The reaction of phenols and anthranils gives 3-aryl anthranils via a C-C bond formation, whereas thiophenols afford 3-thio anthranils through a C-S bond formation. Both reactions have a broad substrate scope and tolerate a wide range of functional groups, affording the corresponding products with specific chemoselectivity.
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Affiliation(s)
- Yupeng Zhao
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, China
| | - Yang Gao
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, China
- Jieyang Branch of Chemistry and Chemical Engineering Guangdong Laboratory, Jieyang 515200, China
| | - Zhongke Xie
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, China
| | - Shuwei Liao
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, China
| | - Jiebin Huang
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, China
| | - Yanping Huo
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, China
| | - Qian Chen
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, China
| | - Xianwei Li
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, China
| | - Xiao-Qiang Hu
- Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education & Hubei Key Laboratory of Catalysis and Materials Science, School of Chemistry and Materials Science, South-Central University for Nationalities, Wuhan 430074, China
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5
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Abstract
Cyclopropanes that carry an electron-accepting group react as electrophiles in polar, ring-opening reactions. Analogous reactions at cyclopropanes with additional C2 substituents allow one to access difunctionalized products. Consequently, functionalized cyclopropanes are frequently used building blocks in organic synthesis. The polarization of the C1-C2 bond in 1-acceptor-2-donor-substituted cyclopropanes not only favorably enhances reactivity toward nucleophiles but also directs the nucleophilic attack toward the already substituted C2 position. Monitoring the kinetics of non-catalytic ring-opening reactions with a series of thiophenolates and other strong nucleophiles, such as azide ions, in DMSO provided the inherent SN2 reactivity of electrophilic cyclopropanes. The experimentally determined second-order rate constants k 2 for cyclopropane ring-opening reactions were then compared to those of related Michael additions. Interestingly, cyclopropanes with aryl substituents at the C2 position reacted faster than their unsubstituted analogues. Variation of the electronic properties of the aryl groups at C2 gave rise to parabolic Hammett relationships.
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Affiliation(s)
- Andreas Eitzinger
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5–13, 81377München, Germany
| | - Armin R. Ofial
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5–13, 81377München, Germany
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6
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Piszel PE, Orzolek BJ, Olszewski AK, Rotella ME, Spiewak AM, Kozlowski MC, Weix DJ. Protodemetalation of (Bipyridyl)Ni(II)-Aryl Complexes Shows Evidence for Five-, Six-, and Seven-Membered Cyclic Pathways. J Am Chem Soc 2023:10.1021/jacs.3c00618. [PMID: 37026854 PMCID: PMC10558627 DOI: 10.1021/jacs.3c00618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
Abstract
Protonation of C-M bonds and its microscopic reverse, metalation of C-H bonds, are fundamental steps in a variety of metal-catalyzed processes. As such, studies on protonation of C-M bonds can shed light on C-H activation. We present here studies on the rate of protodemetalation (PDM) of a suite of arylnickel(II) complexes with various acids that provide evidence for a concerted, cyclic transition state for the PDM of C-Ni bonds and demonstrate that five-, six-, and seven-membered transition states are particularly favorable. Our data show that while the rate of protodemetalation of arylnickel(II) complexes scales with acidity for many acids, several are faster than predicted by pKa. For example, while acetic acid and acetohydroxamic acid are much less acidic than HCl, they both protodemetalate arylnickel(II) complexes significantly faster than HCl. Our data also show how in the case of acetohydroxamic acid, a seven-membered cyclic transition state (CH3C(O)NHOH) can be more favorable than a six-membered transition state (CH3C(O)NHOH). Similarly, five-membered transition states, such as for pyrazole, are highly favorable as well. Comparison of transition state polarization (from density functional theory) compares these new nickel transition states to better-studied precious-metal systems and demonstrates how the base can change the polarization of the transition state giving rise to opposing electronic preferences. Collectively, these studies suggest several new avenues for study in C-H activation as well as approaches to accelerate or slow protodemetalation in nickel catalysis.
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Affiliation(s)
- Paige E. Piszel
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Brandon J. Orzolek
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Alyssa K. Olszewski
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Madeline E. Rotella
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Amanda M. Spiewak
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Marisa C. Kozlowski
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Daniel J. Weix
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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7
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Eisele NF, Peters M, Koszinowski K. Live Monitoring of Anionic Living Polymerizations by Electrospray-Ionization Mass Spectrometry. Chemistry 2023; 29:e202203762. [PMID: 36596722 DOI: 10.1002/chem.202203762] [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: 12/01/2022] [Revised: 12/30/2022] [Accepted: 01/03/2023] [Indexed: 01/05/2023]
Abstract
Anionic polymerizations are of exceptional practical importance, but difficult to analyze due to the high reactivity of the growing polymer chains. Here, we demonstrate that electrospray-ionization mass spectrometry (ESI-MS) permits direct observation of the active carbanionic intermediates formed in the anionic ring-opening polymerization of 1-cyanocyclopropanecarboxylate in tetrahydrofuran. This includes the identification of a side product, as well as real-time analysis of the polymerization reaction. From the mass spectra obtained, we can derive not only the mean molar mass and the polydispersity, but also the rate constants for the initiation and the individual propagation steps. The initiation proceeds significantly faster than the propagation steps. Accordingly, the examined reaction corresponds to a living polymerization, as we also confirmed by additional control experiments. Besides giving detailed insight into the reaction system probed here, we also expect the presented methodology to make possible the in-situ analysis of further anionic polymerizations.
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Affiliation(s)
- Niklas F Eisele
- Institute of Organic and Biomolecular Chemistry, Universität Göttingen, Tammannstraße 2, 37077, Göttingen, Germany
| | - Matthias Peters
- Institute of Organic and Biomolecular Chemistry, Universität Göttingen, Tammannstraße 2, 37077, Göttingen, Germany
| | - Konrad Koszinowski
- Institute of Organic and Biomolecular Chemistry, Universität Göttingen, Tammannstraße 2, 37077, Göttingen, Germany
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8
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Recent Advances in the Use of Dimethyl Sulfoxide as a Synthon in Organic Chemistry. Top Curr Chem (Cham) 2022; 380:55. [DOI: 10.1007/s41061-022-00411-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Accepted: 10/06/2022] [Indexed: 11/27/2022]
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9
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Solvent effect, quantification and correlation analysis of the nucleophilicities of cyclic secondary amines. CHEMICAL PAPERS 2022. [DOI: 10.1007/s11696-022-02483-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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10
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Jüstel PM, Stan A, Pignot CD, Ofial AR. Inherent Reactivity of Spiro-Activated Electrophilic Cyclopropanes. Chemistry 2021; 27:15928-15935. [PMID: 34569669 PMCID: PMC9298281 DOI: 10.1002/chem.202103027] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Indexed: 12/16/2022]
Abstract
The kinetics of the ring-opening reactions of thiophenolates with geminal bis(acceptor)-substituted cyclopropanes in DMSO at 20 °C was monitored by photometric methods. The determined second-order rate constants of the SN 2 reactions followed linear relationships with Mayr nucleophilicity parameters (N/sN ) and Brønsted basicities (pKaH ) of the thiophenolates as well as with Hammett substituent parameters (σ) for groups attached to the thiophenolates. Phenyl-substituted cyclopropanes reacted by up to a factor of 15 faster than their unsubstituted analogues, in accord with the known activating effect of adjacent π-systems in SN 2 reactions. Variation of the electronic properties of substituents at the phenyl groups of the cyclopropanes gave rise to parabolic Hammett relationships. Thus, the inherent SN 2 reactivity of electrophilic cyclopropanes is activated by electron-rich π-systems because of the more advanced C1-C2 bond polarization in the transition state. On the other hand, electron-poor π-systems also lower the energetic barriers for the attack of anionic nucleophiles owing to attractive electrostatic interactions.
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Affiliation(s)
- Patrick M. Jüstel
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstr. 5–1381377MünchenGermany
| | - Alexandra Stan
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstr. 5–1381377MünchenGermany
| | - Cedric D. Pignot
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstr. 5–1381377MünchenGermany
| | - Armin R. Ofial
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstr. 5–1381377MünchenGermany
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11
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Maji B, Duan XH, Jüstel PM, Byrne PA, Ofial AR, Mayr H. Nucleophilicities and Nucleofugalities of Thio- and Selenoethers. Chemistry 2021; 27:11367-11376. [PMID: 34002899 PMCID: PMC8456842 DOI: 10.1002/chem.202100977] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Indexed: 12/19/2022]
Abstract
Rate constants for the reactions of dialkyl chalcogenides with laser flash photolytically generated benzhydrylium ions have been measured photometrically to integrate them into the comprehensive benzhydrylium‐based nucleophilicity scale. Combining these rate constants with the previously reported equilibrium constants for the same reactions provided the corresponding Marcus intrinsic barriers and made it possible to quantify the leaving group abilities (nucleofugalities) of dialkyl sulfides and dimethyl selenide. Due to the low intrinsic barriers, dialkyl chalcogenides are fairly strong nucleophiles (comparable to pyridine and N‐methylimidazole) as well as good nucleofuges; this makes them useful group‐transfer reagents.
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Affiliation(s)
- Biplab Maji
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany.,Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - Xin-Hua Duan
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany.,Department of Chemistry, School of Chemistry, Xi'an Key Laboratory of Sustainable Energy Material Chemistry, Xi'an Jiaotong University, No. 28, Xianning West Road, Xi'an, 710049, P. R. China
| | - Patrick M Jüstel
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany
| | - Peter A Byrne
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany.,School of Chemistry, University College Cork, College Road, Cork, Ireland
| | - Armin R Ofial
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany
| | - Herbert Mayr
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, München, Germany
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