1
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Deshmukh SH, Nachaki EO, Kuroda DG. Uncovering the binding nature of thiocyanate in contact ion pairs with lithium ions. J Chem Phys 2024; 161:034507. [PMID: 39017430 DOI: 10.1063/5.0216491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Accepted: 06/28/2024] [Indexed: 07/18/2024] Open
Abstract
Ion pair formation is a fundamental molecular process that occurs in a wide variety of systems, including electrolytes, biological systems, and materials. In solution, the thiocyanate (SCN-) anion interacts with cations to form contact ion pairs (CIPs). Due to its ambidentate nature, thiocyanate can bind through either its sulfur or nitrogen atoms, depending on the solvent. This study focuses on the binding nature of thiocyanate with lithium ions as a function of the solvents using FTIR, 2D infrared spectroscopy (2DIR) spectroscopies, and theoretical calculations. The study reveals that the SCN- binding mode (S or N end) in CIPs can be identified through 2DIR spectroscopy but not by linear IR spectroscopy. Linear IR spectroscopy shows that the CN stretch frequencies are too close to one another to separate N- and S-bound CIPs. Moreover, the IR spectrum shows that the S-C stretch presents different frequencies for the salt in different solvents, but it is related to the anion speciation rather than to its binding mode. A similar trend is observed for the anion bend. 2DIR spectra show different dynamics for N-bound and S-bound thiocyanate. In particular, the frequency-frequency correlation function (FFCF) dynamics extracted from the 2DIR spectra have a single picosecond exponential decay for N-bound thiocyanate and a biexponential decay for S-bound thiocyanate, consistent with the binding mode of the anion. Finally, it is also observed that the binding mode also affects the line shape parameters, probably due to the different molecular mechanisms of the FFCF for N- and S-bound CIPs.
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Affiliation(s)
- Samadhan H Deshmukh
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA
| | - Ernest O Nachaki
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA
| | - Daniel G Kuroda
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA
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2
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Jiang H, Torigoe T, Kuninobu Y. Boronyl-Group-Assisted Decatungstate-Catalyzed Benzylic C(sp 3)-H Alkylation. Org Lett 2024; 26:4853-4856. [PMID: 38837750 DOI: 10.1021/acs.orglett.4c01043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2024]
Abstract
Boronic acid synthesis primarily involves the introduction of boronyl groups. However, an alternative route that involves the functionalization of boronic acids has not received much attention. This study describes the catalytic C(sp3)-H alkylation of ortho-tolylboronic acids utilizing the interaction between a free boronyl group [-B(OH)2] and a decatungstate photocatalyst [W10O32]4-. The boronyl groups of the alkylated products could be converted without isolation of the alkylated product.
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Affiliation(s)
- Hui Jiang
- Department of Interdisciplinary Engineering Sciences, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasugakoen, Kasuga-shi, Fukuoka 816-8580, Japan
| | - Takeru Torigoe
- Faculty of Molecular Chemistry and Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, Kyoto 606-8585, Japan
| | - Yoichiro Kuninobu
- Department of Interdisciplinary Engineering Sciences, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasugakoen, Kasuga-shi, Fukuoka 816-8580, Japan
- Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasugakoen, Kasuga-shi, Fukuoka 816-8580, Japan
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3
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Docherty P, Kadarauch M, Mistry N, Phipps RJ. Application of sSPhos as a Chiral Ligand for Palladium-Catalyzed Asymmetric Allylic Alkylation. Org Lett 2024; 26:2862-2866. [PMID: 38147571 PMCID: PMC11020163 DOI: 10.1021/acs.orglett.3c04025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 12/18/2023] [Accepted: 12/20/2023] [Indexed: 12/28/2023]
Abstract
Palladium-catalyzed asymmetric allylic alkylation is a versatile method for C-C bond formation. Many established classes of chiral ligands can perform allylic alkylation reactions enantioselectively, but identification of new ligand classes remains important for future development of the field. We demonstrate that enantiopure sSPhos, a bifunctional chiral monophosphine ligand, when used as its tetrabutyl ammonium salt, is a highly effective ligand for a benchmark Pd-catalyzed allylic alkylation reaction. We explore the scope and limitations and perform experiments to probe the origin of selectivity. In contrast with reactions previously explored using enantiopure sSPhos, it appears that steric bulk around the sulfonate group is responsible for the high enantioselectivity in this case, rather than attractive noncovalent interactions.
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Affiliation(s)
- Philip
J. Docherty
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
| | - Max Kadarauch
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
| | - Nisha Mistry
- Drug
Substance Development, GSK, Stevenage SG1 2NY, U.K.
| | - Robert J. Phipps
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
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4
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Li K, Qin WM, Su WX, Hu JM, Cai YP. Chiral BINOL-phosphate assembled single hexagonal nanotube in aqueous solution for confined rearrangement acceleration. Nat Commun 2024; 15:2799. [PMID: 38555282 PMCID: PMC10981660 DOI: 10.1038/s41467-024-47150-6] [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: 10/06/2023] [Accepted: 03/20/2024] [Indexed: 04/02/2024] Open
Abstract
Creating microenvironments that mimic an enzyme's active site is a critical aspect of supramolecular confined catalysis. In this study, we employ the commonly used chiral 1,1'-bi-2-naphthol (BINOL) phosphates as subcomponents to construct supramolecular hollow nanotube in an aqueous medium through non-covalent intermolecular recognition and arrangement. The hexagonal nanotubular structure is characterized by various techniques, including X-ray, NMR, ESI-MS, AFM, and TEM, and is confirmed to exist in a homogeneous aqueous solution stably. The nanotube's length in solution depends on the concentration of chiral BINOL-phosphate as a monomer. Additionally, the assembled nanotube can accelerate the rate of the 3-aza-Cope rearrangement reaction by up to 85-fold due to the interior confinement effect. Based on the detailed kinetic and thermodynamic analyses, we propose that the chain-like substrates are constrained and pre-organized into a reactive chair-like conformation, which stabilizes the transition state of the reaction in the confined nanospace of the nanotube. Notably, due to the restricted conformer with less degrees of freedom, the entropic barrier is significantly reduced compared to the enthalpic barrier, resulting in a more pronounced acceleration effect.
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Affiliation(s)
- Kang Li
- School of Chemistry, South China Normal University, Guangzhou, 510006, China.
- Guangzhou Key Laboratory of Energy Conversion and Energy Storage Materials, Guangzhou, 510006, China.
- The Joint Laboratory of Energy Materials Chemistry for SCNU and TINCI, Guangzhou, 510006, China.
| | - Wei-Min Qin
- School of Chemistry, South China Normal University, Guangzhou, 510006, China
| | - Wen-Xia Su
- School of Chemistry, South China Normal University, Guangzhou, 510006, China
| | - Jia-Min Hu
- School of Chemistry, South China Normal University, Guangzhou, 510006, China
| | - Yue-Peng Cai
- School of Chemistry, South China Normal University, Guangzhou, 510006, China.
- Guangzhou Key Laboratory of Energy Conversion and Energy Storage Materials, Guangzhou, 510006, China.
- The Joint Laboratory of Energy Materials Chemistry for SCNU and TINCI, Guangzhou, 510006, China.
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5
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Brunard E, Boquet V, Saget T, Sosa Carrizo ED, Sircoglou M, Dauban P. Catalyst-Controlled Intermolecular Homobenzylic C(sp 3)-H Amination for the Synthesis of β-Arylethylamines. J Am Chem Soc 2024; 146:5843-5854. [PMID: 38387076 DOI: 10.1021/jacs.3c10964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2024]
Abstract
The combination of a tailored sulfamate with a C4-symmetrical rhodium(II) tetracarboxylate allows to uncover a selective intermolecular amination of unactivated homobenzylic C(sp3)-H bonds. The reaction has a broad scope (>30 examples) and proceeds with a high level of regioselectivity with homobenzylic/benzylic ratio of up to 35:1, thereby providing a direct access to β-arylethylamines that are of utmost interest in medicinal chemistry. Computational investigations evidenced a concerted mechanism, involving an asynchronous transition state. Based on a combined activation strain model and energy decomposition analysis, the regioselectivity of the reaction was found to rely mainly on the degree of orbital interaction between the [Rh2]-nitrene and the C-H bond. The latter is facilitated at the homobenzylic position due to the establishment of specific noncovalent interactions within the catalytic pocket.
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Affiliation(s)
- Erwan Brunard
- Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, UPR 2301, 91198 Gif-sur-Yvette, France
| | - Vincent Boquet
- Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, UPR 2301, 91198 Gif-sur-Yvette, France
| | - Tanguy Saget
- Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, UPR 2301, 91198 Gif-sur-Yvette, France
| | - E Daiann Sosa Carrizo
- Université Paris-Saclay, CNRS, Institut de Chimie Moléculaire et des Matériaux d'Orsay, 91400 Orsay, France
| | - Marie Sircoglou
- Université Paris-Saclay, CNRS, Institut de Chimie Moléculaire et des Matériaux d'Orsay, 91400 Orsay, France
| | - Philippe Dauban
- Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, UPR 2301, 91198 Gif-sur-Yvette, France
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6
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Das A, Mandal R, Ravi Sankar HS, Kumaran S, Premkumar JR, Borah D, Sundararaju B. Reversal of Regioselectivity in Asymmetric C-H Bond Annulation with Bromoalkynes under Cobalt Catalysis. Angew Chem Int Ed Engl 2024; 63:e202315005. [PMID: 38095350 DOI: 10.1002/anie.202315005] [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: 10/06/2023] [Indexed: 12/30/2023]
Abstract
Metal-catalyzed asymmetric C-H bond annulation strategy offers a versatile platform, allowing the construction of complex P-chiral molecules through atom- and step-economical fashion. However, regioselective insertion of π-coupling partner between M-C bond with high enantio-induction remain elusive. Using commercially available Co(II) salt and chiral-Salox ligands, we demonstrate an unusual protocol for the regio-reversal, enantioselective C-H bond annulation of phosphinamide with bromoalkyne through desymmetrization. The reaction proceeds through ligand-assisted enantiodetermining cyclocobaltation followed by regioselective insertion of bromoalkyne between Co-C, subsequent reductive elimination, and halogen exchange with carboxylate resulted in P-stereogenic compounds in excellent ee (up to >99 %). The isolation of cobaltacycle involved in the catalytic cycle and the outcome of control experiments provide support for a plausible mechanism.
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Affiliation(s)
- Abir Das
- Department of Chemistry, Indian Institution of Technology Kanpur, 208016, Kanpur, Uttar Pradesh, India
| | - Rajib Mandal
- Department of Chemistry, Indian Institution of Technology Kanpur, 208016, Kanpur, Uttar Pradesh, India
| | | | - Subramani Kumaran
- Department of Chemistry, Indian Institution of Technology Kanpur, 208016, Kanpur, Uttar Pradesh, India
| | - J Richard Premkumar
- PG & Research Department of Chemistry, Bishop Heber College, 620017, Tiruchirappalli, Tamil Nadu, India
| | - Dipanti Borah
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, 400076, Mumbai, Maharashtra, India
| | - Basker Sundararaju
- Department of Chemistry, Indian Institution of Technology Kanpur, 208016, Kanpur, Uttar Pradesh, India
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7
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Lv Q, Hu Z, Zhang Y, Zhang Z, Lei H. Advancing Meta-Selective C-H Amination through Non-Covalent Interactions. J Am Chem Soc 2024; 146:1735-1741. [PMID: 38095630 DOI: 10.1021/jacs.3c09904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2024]
Abstract
Regioselective C-H amination of simple arenes is highly desirable, but accessing meta-sites of ubiquitous arenes has proven challenging due to the lack of both electronic and spatial preference. This study demonstrates the successful use of various privileged nitrogen-containing functionalities found in pharmaceutical compounds to direct meta-C-H amination of arenes, overcoming the long-standing requirement for a redundant directing group. The remarkable advancements in functional group accommodation for precise regiochemical control were achieved through the discovery of an unprecedented organo-initiator and the strategic utilization of non-covalent interactions. This protocol has been successfully applied in the concise synthesis and late-stage derivatization of drug molecules, which would have been otherwise challenging to achieve.
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Affiliation(s)
- Qianqian Lv
- College of Chemistry, Central China Normal University, Wuhan, Hubei 430079, P. R. China
| | - Zongxing Hu
- College of Chemistry, Central China Normal University, Wuhan, Hubei 430079, P. R. China
| | - Yousong Zhang
- College of Chemistry, Central China Normal University, Wuhan, Hubei 430079, P. R. China
| | - Zhihan Zhang
- College of Chemistry, Central China Normal University, Wuhan, Hubei 430079, P. R. China
- Wuhan Institute of Photochemistry and Technology, Wuhan, Hubei 430083, P. R. China
| | - Honghui Lei
- College of Chemistry, Central China Normal University, Wuhan, Hubei 430079, P. R. China
- Wuhan Institute of Photochemistry and Technology, Wuhan, Hubei 430083, P. R. China
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8
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Iribarren I, Mates-Torres E, Trujillo C. Revisiting ion-pair interactions in phase transfer catalysis: from ionic compounds to real catalyst systems. Dalton Trans 2024; 53:1322-1335. [PMID: 38116737 DOI: 10.1039/d3dt03978a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Ion-pairing is a fundamental phenomenon that significantly influences phase-transfer catalysis. In this study, we conduct a comprehensive investigation of ion-pair interactions, aiming to establish a comprehensive understanding of their nature and implications. The study begins with the examination of polar ionic compounds to define the concept of an ion-pair in the context of phase-transfer catalysis. Subsequently, a diverse range of ion-pair catalyst models were explored to gain insight into the factors governing their interactions. Finally, the focus shifts towards the characterisation of real phase-transfer catalysts, bridging the gap between theoretical models and practical applications. Through a combination of computational approaches and theoretical analysis, this work provides valuable insight into the nature of ion-pair interactions within phase-transfer catalysis fields.
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Affiliation(s)
- Iñigo Iribarren
- School of Chemistry, Trinity College Dublin, The University of Dublin, 154-160 Pearse Street, D02 R590 Dublin, Ireland
| | - Eric Mates-Torres
- School of Chemistry, Trinity College Dublin, The University of Dublin, 154-160 Pearse Street, D02 R590 Dublin, Ireland
| | - Cristina Trujillo
- School of Chemistry, Trinity College Dublin, The University of Dublin, 154-160 Pearse Street, D02 R590 Dublin, Ireland
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9
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Burks R, Öhrström L, Amombo Noa FM. Clarifying the complex chemistry of cobalt(II) thiocyanate-based tests for cocaine using single-crystal X-ray diffraction and spectroscopic techniques. J Forensic Sci 2024; 69:291-300. [PMID: 37853665 DOI: 10.1111/1556-4029.15403] [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: 08/04/2023] [Revised: 09/22/2023] [Accepted: 09/28/2023] [Indexed: 10/20/2023]
Abstract
Cobalt(II) thiocyanate-based tests are routinely used to screen cocaine products, with the formation of a blue species interpreted as a positive response. An array of other organic bases has been identified as false positives - including well-documented cocaine product adulterant lidocaine and its salt. False positives prompt continued test development, though improvements are hindered by unresolved product structures and reaction pathways. Toward greater clarity, cobalt(II) thiocyanate reactions with cocaine hydrochloride, along with lidocaine and its salt, were investigated using multiple analytical techniques. Reactions involving cocaine hydrochloride yielded glassy, amorphous blue material while reactions of lidocaine hydrochloride monohydrate produced larger, needle-like crystals whose structure was determined via single-crystal X-ray diffraction to be an ion pair (Hlidocaine+ )2 ([Co(SCN)4 ]2- )·H2 O. While the blue precipitate isolated from reactions involving cocaine hydrochloride was unsuitable for crystallographic structure determination, comparative ultraviolet-visible, attenuated total reflectance infrared, and Raman spectroscopic analysis - along with elemental analysis - supports that this solid is comprised of a comparable ion pair (Hcocaine+ )2 [Co(SCN)4 ]2- . Pink crystals isolated from lidocaine reaction vessels were identified as coordination compounds cis-[CoL2 (SCN)2 ] and trans-[CoL2 (SCN)2 ] where L = lidocaine, while pink crystals from both cocaine hydrochloride and lidocaine hydrochloride monohydrate reaction vessels were the coordination polymer trans-[Co(H2 O)2 (SCN)2 ]·H2 O. The results presented herein enable reaction optimization to favor a desired product, whether ion pair or coordination species.
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Affiliation(s)
- Raychelle Burks
- Department of Chemistry, American University, Washington, District of Columbia, USA
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Lars Öhrström
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Francoise M Amombo Noa
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, Sweden
- AstraZeneca, Mölndal, Sweden
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10
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King RP, Yang JY. Modular preparation of cationic bipyridines and azaarenes via C-H activation. Chem Sci 2023; 14:13530-13536. [PMID: 38033896 PMCID: PMC10686024 DOI: 10.1039/d3sc04864k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 11/05/2023] [Indexed: 12/02/2023] Open
Abstract
Bipyridines are ubiquitous in organic and inorganic chemistry because of their redox and photochemical properties and their utility as ligands to transition metals. Cationic substituents on bipyridines and azaarenes are valuable as powerful electron-withdrawing functionalities that also enhance solubility in polar solvents, but there are no general methods for direct functionalization. A versatile method for the preparation of trimethylammonium- and triarylphosphonium-substituted bipyridines and azaheterocycles is disclosed. This methodology showcases a C-H activation of pyridine N-oxides that enables a highly modular and scalable synthesis of a diverse array of cationically charged azaarenes. The addition of trimethylammonium functionalities on bipyridine derivatives resulted in more anodic reduction potentials (up to 700 mV) and increased electrochemical reversibility compared to the neutral unfunctionalized bipyridine. Additonally, metallation of 4-triphenylphosphinated biquinoline to make the corresponding Re(CO)3Cl complex resulted in reduction potentials 400 mV more anodic than the neutral derivative.
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Affiliation(s)
- Ryan P King
- Department of Chemistry, University of California, Irvine Irvine CA 92697 USA
| | - Jenny Y Yang
- Department of Chemistry, University of California, Irvine Irvine CA 92697 USA
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11
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Yuan Z, Britton R. Development and application of decatungstate catalyzed C-H 18F- and 19F-fluorination, fluoroalkylation and beyond. Chem Sci 2023; 14:12883-12897. [PMID: 38023504 PMCID: PMC10664588 DOI: 10.1039/d3sc04027e] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 10/11/2023] [Indexed: 12/01/2023] Open
Abstract
Over the past few decades, photocatalytic C-H functionalization reactions have received increasing attention due to the often mild reaction conditions and complementary selectivities to conventional functionalization processes. Now, photocatalytic C-H functionalization is a widely employed tool, supporting activities ranging from complex molecule synthesis to late-stage structure-activity relationship studies. In this perspective, we will discuss our efforts in developing a photocatalytic decatungstate catalyzed C-H fluorination reaction as well as its practical application realized through collaborations with industry partners at Hoffmann-La Roche and Merck, and extension to radiofluorination with radiopharmaceutical chemists and imaging experts at TRIUMF and the BC Cancer Agency. Importantly, we feel that our efforts address a question of utility posed by Professor Tobias Ritter in "Late-Stage Fluorination: Fancy Novelty or Useful Tool?" (ACIE, 2015, 54, 3216). In addition, we will discuss decatungstate catalyzed C-H fluoroalkylation and the interesting electrostatic effects observed in decatungstate-catalyzed C-H functionalization. We hope this perspective will inspire other researchers to explore the use of decatungstate for the purposes of photocatalytic C-H functionalization and further advance the exploitation of electrostatic effects for both rate acceleration and directing effects in these reactions.
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Affiliation(s)
- Zheliang Yuan
- Department of Chemistry, Simon Fraser University Burnaby British Columbia V5A 1S2 Canada
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Department of Chemistry, Zhejiang Normal University Jinhua Zhejiang 321004 China
| | - Robert Britton
- Department of Chemistry, Simon Fraser University Burnaby British Columbia V5A 1S2 Canada
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12
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Ermanis K, Gibson DC, Genov GR, Phipps RJ. Interrogating the Crucial Interactions at Play in the Chiral Cation-Directed Enantioselective Borylation of Arenes. ACS Catal 2023; 13:13043-13055. [PMID: 37822864 PMCID: PMC10563137 DOI: 10.1021/acscatal.3c03384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 08/28/2023] [Indexed: 10/13/2023]
Abstract
Rendering a common ligand scaffold anionic and then pairing it with a chiral cation represents an alternative strategy for developing enantioselective versions of challenging transformations, as has been recently demonstrated in the enantioselective borylation of arenes using a quinine-derived chiral cation. A significant barrier to the further generalization of this approach is the lack of understanding of the specific interactions involved between the cation, ligand, and substrate, given the complexity of the system. We have embarked on a detailed computational study probing the mechanism, the key noncovalent interactions involved, and potential origin of selectivity for the desymmetrizing borylation of two distinct classes of substrate. We describe a deconstructive, stepwise approach to tackling this complex challenge, which involves building up a detailed understanding of the pairwise components of the nominally three component system before combining together into the full 263-atom reactive complex. This approach has revealed substantial differences in the noncovalent interactions occurring at the stereodetermining transition state for C-H oxidative addition to iridium for the two substrate classes. Each substrate engages in a unique mixture of diverse interactions, a testament to the rich and privileged structure of the cinchona alkaloid-derived chiral cations. Throughout the study, experimental support is provided, and this culminates in the discovery that prochiral phosphine oxide substrates, lacking hydrogen bond donor functionality, can also give very encouraging levels of enantioselectivity, potentially through direct interactions with the chiral cation. We envisage that the findings in this study will spur further developments in using chiral cations as controllers in asymmetric transition-metal catalysis.
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Affiliation(s)
- Kristaps Ermanis
- School
of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United
Kingdom
| | - David C. Gibson
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Georgi R. Genov
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Robert J. Phipps
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
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13
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Gillespie JE, Lam NYS, Phipps RJ. Ortho-Selective amination of arene carboxylic acids via rearrangement of acyl O-hydroxylamines. Chem Sci 2023; 14:10103-10111. [PMID: 37772106 PMCID: PMC10530477 DOI: 10.1039/d3sc03293k] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 08/17/2023] [Indexed: 09/30/2023] Open
Abstract
Direct amination of arene C-H bonds is an attractive disconnection to form aniline-derived building blocks. This transformation presents significant practical challenges; classical methods for ortho-selective amination require strongly acidic or forcing conditions, while contemporary catalytic processes often require bespoke directing groups and/or precious metal catalysis. We report a mild and procedurally straightforward ortho-selective amination of arene carboxylic acids, arising from a facile rearrangement of acyl O-hydroxylamines without requiring precious metal catalysts. A broad scope of benzoic acid substrates are compatible and the reaction can be applied to longer chain arene carboxylic acids. Mechanistic studies probe the specific requirement for trifluoroacetic acid in generating the active aminating agent, and suggest that two separate mechanisms may be operating in parallel in the presence of an iron catalyst: (i) an iron-nitrenoid intermediate and (ii) a radical chain pathway. Regardless of which mechanism is followed, high ortho selectivity is obtained, proposed to arise from the directivity (first) or attractive interactions (second) arising with the carboxylic acid motif.
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Affiliation(s)
- James E Gillespie
- Yusuf Hamied Department of Chemistry, University of Cambridge Lensfield Road Cambridge CB2 1EW UK
| | - Nelson Y S Lam
- Yusuf Hamied Department of Chemistry, University of Cambridge Lensfield Road Cambridge CB2 1EW UK
| | - Robert J Phipps
- Yusuf Hamied Department of Chemistry, University of Cambridge Lensfield Road Cambridge CB2 1EW UK
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14
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Abuhafez N, Gramage-Doria R. Boosting the activity of Mizoroki-Heck cross-coupling reactions with a supramolecular palladium catalyst favouring remote Zn⋯pyridine interactions. Faraday Discuss 2023; 244:186-198. [PMID: 37083293 DOI: 10.1039/d2fd00165a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Transition metal catalysis benefitting from supramolecular interactions in the secondary coordination sphere in order to pre-organize substrates around the active site and reach a specific selectivity typically occurs under long reaction times and mild reaction temperatures with the aim to maximize such subtle effects. Herein, we demonstrate that the kinetically labile Zn⋯N interaction between a pyridine substrate and a zinc-porphyrin site serving for substrate binding is a unique type of weak interaction that enables identification of supramolecular effects in transition metal catalysis after one hour at a high reaction temperature of 130 °C. Under carefully selected reaction conditions, supramolecularly-regulated palladium-catalyzed Mizoroki-Heck reactions between 3-bromopyridine and terminal olefins (acrylates or styrenes) proceeded in a more efficient manner compared to the non-supramolecular version. The supramolecular catalysis developed here also displayed interesting substrate-selectivity patterns.
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Affiliation(s)
- Naba Abuhafez
- Univ Rennes, CNRS, ISCR-UMR6226, F-35000 Rennes, France.
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15
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Wei J, Gandon V, Zhu Y. Amino Acid-Derived Ionic Chiral Catalysts Enable Desymmetrizing Cross-Coupling to Remote Acyclic Quaternary Stereocenters. J Am Chem Soc 2023; 145:16796-16811. [PMID: 37471696 PMCID: PMC10401725 DOI: 10.1021/jacs.3c04877] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/22/2023]
Abstract
Synthetic application of asymmetric catalysis relies on strategic alignment of bond construction to creation of chirality of a target molecule. Remote desymmetrization offers distinctive advantages of spatial decoupling of catalytic transformation and generation of a stereogenic element. However, such spatial separation presents substantial difficulties for the chiral catalyst to discriminate distant enantiotopic sites through a reaction three or more bonds away from a prochirality center. Here, we report a strategy that establishes acyclic quaternary carbon stereocenters through cross-coupling reactions at distal positions of aryl substituents. The new class of amino acid-derived ionic chiral catalysts enables desymmetrizing (enantiotopic-group-selective) Suzuki-Miyaura reaction, Sonogashira reaction, and Buchwald-Hartwig amination between diverse diarylmethane scaffolds and aryl, alkynyl, and amino coupling partners, providing rapid access to enantioenriched molecules that project substituents to widely spaced positions in the three-dimensional space. Experimental and computational investigations reveal electrostatic steering of substrates by the C-terminus of chiral ligands through ionic interactions. Cooperative ion-dipole interactions between the catalyst's amide group and potassium cation aid in the preorganization that transmits asymmetry to the product. This study demonstrates that it is practical to achieve precise long-range stereocontrol through engineering the spatial arrangements of the ionic catalysts' substrate-recognizing groups and metal centers.
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Affiliation(s)
- Junqiang Wei
- Department of Chemistry, Faculty of Science, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Vincent Gandon
- Institut de Chimie Moléculaire et des Matériaux d'Orsay (UMR CNRS 8182), Paris-Saclay University, bâtiment Hesnri Moissan, 17 avenue des sciences, 91400 Orsay, France
| | - Ye Zhu
- Department of Chemistry, Faculty of Science, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
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Sorensen CC, Kozuszek CT, Borden MA, Leibfarth FA. Asymmetric Ion-Pairing in Stereoselective Vinyl Polymerization. ACS Catal 2023. [DOI: 10.1021/acscatal.3c00040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Affiliation(s)
- Cole C. Sorensen
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Caleb T. Kozuszek
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Meredith A. Borden
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Frank A. Leibfarth
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
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Non-covalent interactions in transition metal-catalyzed para-selective C H functionalization of arenes. ADVANCES IN ORGANOMETALLIC CHEMISTRY 2023. [DOI: 10.1016/bs.adomc.2023.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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