1
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Wang Y, Li SJ, Jiang F, Lan Y, Wang X. Making Full Use of TMSCF 3: Deoxygenative Trifluoromethylation/Silylation of Amides. J Am Chem Soc 2024; 146:19286-19294. [PMID: 38956888 DOI: 10.1021/jacs.4c04760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
As one of the most powerful trifluoromethylation reagents, (trifluoromethyl)trimethylsilane (TMSCF3) has been widely used for the synthesis of fluorine-containing molecules. However, to the best of our knowledge, the simultaneous incorporation of both TMS- and CF3- groups of this reagent onto the same carbon of the products has not been realized. Herein, we report an unprecedented SmI2/Sm promoted deoxygenative difunctionalization of amides with TMSCF3, in which both silyl and trifluoromethyl groups are incorporated into the final product, yielding α-silyl-α-trifluoromethyl amines with high efficiency. Notably, the silyl group could be further transformed into other functional groups, providing a new method for the synthesis of α-quaternary α-CF3-amines.
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Affiliation(s)
- Yuxiao Wang
- State Key Laboratory of Organometallic Chemistry and Shanghai Hongkong Joint Laboratory in Chemical Synthesis, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Shi-Jun Li
- Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou 450001, China
| | - Feng Jiang
- State Key Laboratory of Organometallic Chemistry and Shanghai Hongkong Joint Laboratory in Chemical Synthesis, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Yu Lan
- Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou 450001, China
- School of Chemistry and Chemical Engineering and Chongqing Key Laboratory of Theoretical and Computational Chemistry, Chongqing University, Chongqing 400030, China
| | - Xiaoming Wang
- State Key Laboratory of Organometallic Chemistry and Shanghai Hongkong Joint Laboratory in Chemical Synthesis, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, 1 Sub-lane Xiangshan, Hangzhou 310024, China
- School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang 453007, China
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2
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Minshull H, Lloyd-Jones GC. TMSCF 3-Mediated Conversion of Salicylates into α,α-Difluoro-3-coumaranones: Chain Kinetics, Anion-Speciation, and Mechanism. J Org Chem 2023; 88:17450-17460. [PMID: 38041656 PMCID: PMC10729029 DOI: 10.1021/acs.joc.3c02219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/13/2023] [Accepted: 11/15/2023] [Indexed: 12/03/2023]
Abstract
As reported by Zhao, the TBAT ([Ph3SiF2]-[Bu4N]+)-initiated reaction of ethyl salicylate with TMSCF3 in THF generates α,α-difluoro-3-coumaranones via the corresponding O-silylated ethoxy ketals. The mechanism has been investigated by in situ 19F and 29Si NMR spectroscopy, CF2-trapping, competition, titration, and comparison of the kinetics with the 3-, 4-, 5-, and 6-fluoro ethyl salicylate analogues and their O-silylated derivatives. The process evolves in five distinct stages, each arising from a discrete array of anion speciations that modulate a sequence of silyl-transfer chain reactions. The deconvolution of coupled equilibria between salicylate, [CF3]-, and siliconate [Me3Si(CF3)2]- anions allowed the development of a kinetic model that accounts for the first three stages. The model provides valuable practical insights. For example, it explains how the initial concentrations of the TMSCF3 and salicylate and the location of electron-withdrawing salicylate ring substituents profoundly impact the overall viability of the process, how stoichiometric CF3H generation can be bypassed by using the O-silylated salicylate, and how the very slow liberation of the α,α-difluoro-3-coumaranone can be rapidly accelerated by evaporative or aqueous workup.
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Affiliation(s)
- Hannah
B. Minshull
- School of Chemistry, University of Edinburgh, Joseph Black Building, Edinburgh EH9 3FJ, U.K.
| | - Guy C. Lloyd-Jones
- School of Chemistry, University of Edinburgh, Joseph Black Building, Edinburgh EH9 3FJ, U.K.
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3
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Quan X, Xu L, Li Z, Maienfisch P. Design, Synthesis, and Properties of Silicon-Containing meta-Diamide Insecticides. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:18188-18196. [PMID: 37191337 DOI: 10.1021/acs.jafc.3c01342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Silicon-containing compounds are sporadically used in crop protection and drug discovery and have demonstrated to increase the biological efficacy as well as to reduce toxicity, improve physicochemical properties, and favorably impact the environmental profile. As part of our research, we have investigated the application of bioisosteric silicon replacements in meta-diamide insecticides and studied the biological activity and molecular properties of the corresponding novel compounds. At all meaningful structural elements of the meta-diamides, silicon-containing substituents were introduced and synthetic methodology was developed for their syntheses. As the most promising compound, silicon-containing meta-diamide II-18 emerged, which exhibits a very low LC50 value of 2.00 mg/L against Mythimna separata and compares well to the reference compounds 28 (LC50 = 0.17 mg/L) and II-20 (LC50 = 0.27 mg/L). Our research on silicon-containing crop protection compounds once again confirmed that the biological activity can be beneficially affected by the insertion of silicone substituents and that the introduction of well-chosen silicone motifs is an excellent strategy for agrochemical research.
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Affiliation(s)
- Xiaocao Quan
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, People's Republic of China
| | - Liu Xu
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, People's Republic of China
| | - Zhong Li
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, People's Republic of China
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, People's Republic of China
| | - Peter Maienfisch
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, People's Republic of China
- CreInSol Consulting & Biocontrols, CH-4118 Rodersdorf, Switzerland
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4
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Kvasha DA, Deviatkin A, Poturai AS, Nosik PS, Kyrylchuk AA, Suikov S, Rozhenko AB, Volochnyuk DM, Grygorenko OO. Metal-Free C-H Difluoromethylation of Imidazoles with the Ruppert-Prakash Reagent. J Org Chem 2023; 88:163-171. [PMID: 36520999 DOI: 10.1021/acs.joc.2c02041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The reaction of trimethyl(trifluoromethyl)silane-tetrabutylammonium difluorotriphenylsilicate (CF3SiMe3-TBAT) with a series of imidazoles gives products of the formal difluorocarbene insertion into the C-H bond at the C-2 position (i.e., C-difluoromethylation). According to NMR spectra, the corresponding 2-(trimethylsilyl)difluoromethyl-substituted derivatives are likely formed as the intermediates in the reaction, and then, they slowly convert to 2-difluoromethyl-substituted imidazoles. Quantum chemical calculations of two plausible reaction mechanisms indicate that it proceeds through the intermediate imidazolide anion stabilized through the interaction with solvent molecules and counterions. In the first proposed mechanism, the anion reacts with difluorocarbene without an activation barrier, and then, the CF2 moiety of the adduct attacks the CF3SiMe3 molecule. After the elimination of the CF3 anion, 2-(trimethylsilyl)difluromethyl-substituted imidazole is formed. Another possible reaction pathway includes silylation of imidazolide anion at the N-3 atom, followed by the barrierless addition of difluorocarbene at the C-2 atom and then by 1,3-shift of the SiMe3 group from N-3 to the carbon atom of the CF2 moiety. Both proposed mechanisms do not include steps with high activation barriers.
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Affiliation(s)
- Denys A Kvasha
- Enamine Ltd., Chervonotkatska Str. 78, Kyïv 02094, Ukraine.,Taras Shevchenko National University of Kyiv, Volodymyrska Street 60, Kyïv 01601, Ukraine
| | - Andrii Deviatkin
- Enamine Ltd., Chervonotkatska Str. 78, Kyïv 02094, Ukraine.,Taras Shevchenko National University of Kyiv, Volodymyrska Street 60, Kyïv 01601, Ukraine
| | | | - Pavel S Nosik
- Enamine Ltd., Chervonotkatska Str. 78, Kyïv 02094, Ukraine.,Taras Shevchenko National University of Kyiv, Volodymyrska Street 60, Kyïv 01601, Ukraine
| | - Andrii A Kyrylchuk
- Enamine Ltd., Chervonotkatska Str. 78, Kyïv 02094, Ukraine.,Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Akademik Kukhar Str. 5, Kyïv 02094, Ukraine
| | - Sergiy Suikov
- Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Akademik Kukhar Str. 5, Kyïv 02094, Ukraine
| | - Alexander B Rozhenko
- Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Akademik Kukhar Str. 5, Kyïv 02094, Ukraine.,University of Bielefeld, Universitätstrasse 25, 33615 Bielefeld, Germany
| | - Dmitriy M Volochnyuk
- Enamine Ltd., Chervonotkatska Str. 78, Kyïv 02094, Ukraine.,Taras Shevchenko National University of Kyiv, Volodymyrska Street 60, Kyïv 01601, Ukraine.,Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Akademik Kukhar Str. 5, Kyïv 02094, Ukraine
| | - Oleksandr O Grygorenko
- Enamine Ltd., Chervonotkatska Str. 78, Kyïv 02094, Ukraine.,Taras Shevchenko National University of Kyiv, Volodymyrska Street 60, Kyïv 01601, Ukraine
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5
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Choi K, Mormino MG, Kalkman ED, Park J, Hartwig JF. Palladium-Catalyzed Aryldifluoromethylation of Aryl Halides with Aryldifluoromethyl Trimethylsilanes. Angew Chem Int Ed Engl 2022; 61:e202208204. [PMID: 35960816 PMCID: PMC9530024 DOI: 10.1002/anie.202208204] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Indexed: 11/12/2022]
Abstract
Diaryl difluoromethanes are valuable targets for medicinal chemistry because they are bioisosteres of diaryl ethers and can function as replacements for diaryl methane, ketone, and sulfone groups. However, methods to prepare diaryl difluoromethanes are scarce, especially methods starting from abundant aryl halides. We report the Pd-catalyzed aryldifluoromethylation of aryl halides with aryldifluoromethyl trimethylsilanes (TMSCF2 Ar). The reaction occurs when the catalyst contains a simple, but unusual, dialkylaryl phosphine ligand that promotes transmetallation of the silane. Computational studies show that reductive elimination following transmetallation occurs with a low barrier, despite the fluorine atoms on the α-carbon, due to coordination of the difluorobenzyl π-system to palladium. The co-development of a cobalt-catalyzed synthesis of the silanes broadened the scope of the process including several applications to the synthesis biologically relevant diaryl difluoromethanes.
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Affiliation(s)
- Kyoungmin Choi
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Michael G. Mormino
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Eric D. Kalkman
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - John Park
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - John F. Hartwig
- Department of Chemistry, University of California, Berkeley, California 94720, United States
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6
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Choi K, Mormino MG, Kalkman ED, Park J, Hartwig JF. Palladium‐Catalyzed Aryldifluoromethylation of Aryl Halides with Aryldifluoromethyl Trimethylsilanes. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202208204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Kyoungmin Choi
- University of California Berkeley Chemistry UNITED STATES
| | | | | | - John Park
- University of California Berkeley Chemistry UNITED STATES
| | - John F. Hartwig
- University of California Department of Chemistry 718 LATIMER HALL #1460 94720-1460 Berkeley UNITED STATES
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7
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Pd/Fe3O4 supported on bio-waste derived cellulosic-carbon as a nanocatalyst for C-C coupling and electrocatalytic application. Front Chem Sci Eng 2022. [DOI: 10.1007/s11705-022-2158-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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8
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García-Domínguez A, Leach AG, Lloyd-Jones GC. In Situ Studies of Arylboronic Acids/Esters and R 3SiCF 3 Reagents: Kinetics, Speciation, and Dysfunction at the Carbanion-Ate Interface. Acc Chem Res 2022; 55:1324-1336. [PMID: 35435655 PMCID: PMC9069690 DOI: 10.1021/acs.accounts.2c00113] [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: 01/06/2023]
Abstract
Reagent instability reduces the efficiency of chemical processes, and while much effort is devoted to reaction optimization, less attention is paid to the mechanistic causes of reagent decomposition. Indeed, the response is often to simply use an excess of the reagent. Two reaction classes with ubiquitous examples of this are the Suzuki-Miyaura cross-coupling of boronic acids/esters and the transfer of CF3 or CF2 from the Ruppert-Prakash reagent, TMSCF3. This Account describes some of the overarching features of our mechanistic investigations into their decomposition. In the first section we summarize how specific examples of (hetero)arylboronic acids can decompose via aqueous protodeboronation processes: Ar-B(OH)2 + H2O → ArH + B(OH)3. Key to the analysis was the development of a kinetic model in which pH controls boron speciation and heterocycle protonation states. This method revealed six different protodeboronation pathways, including self-catalysis when the pH is close to the pKa of the boronic acid, and protodeboronation via a transient aryl anionoid pathway for highly electron-deficient arenes. The degree of "protection" of boronic acids by diol-esterification is shown to be very dependent on the diol identity, with six-membered ring esters resulting in faster protodeboronation than the parent boronic acid. In the second section of the Account we describe 19F NMR spectroscopic analysis of the kinetics of the reaction of TMSCF3 with ketones, fluoroarenes, and alkenes. Processes initiated by substoichiometric "TBAT" ([Ph3SiF2][Bu4N]) involve anionic chain reactions in which low concentrations of [CF3]- are rapidly and reversibly liberated from a siliconate reservoir, [TMS(CF3)2][Bu4N]. Increased TMSCF3 concentrations reduce the [CF3]- concentration and thus inhibit the rates of CF3 transfer. Computation and kinetics reveal that the TMSCF3 intermolecularly abstracts fluoride from [CF3]- to generate the CF2, in what would otherwise be an endergonic α-fluoride elimination. Starting from [CF3]- and CF2, a cascade involving perfluoroalkene homologation results in the generation of a hindered perfluorocarbanion, [C11F23]-, and inhibition. The generation of CF2 from TMSCF3 is much more efficiently mediated by NaI, and in contrast to TBAT, the process undergoes autoacceleration. The process involves NaI-mediated α-fluoride elimination from [CF3][Na] to generate CF2 and a [NaI·NaF] chain carrier. Chain-branching, by [(CF2)3I][Na] generated in situ (CF2 + TFE + NaI), causes autoacceleration. Alkenes that efficiently capture CF2 attenuate the chain-branching, suppress autoacceleration, and lead to less rapid difluorocyclopropanation. The Account also highlights how a collaborative approach to experiment and computation enables mechanistic insight for control of processes.
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Affiliation(s)
- Andrés García-Domínguez
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K
| | - Andrew G. Leach
- School of Health Sciences, Stopford Building, The University of Manchester, Oxford Road, Manchester M13 9PT, U.K
| | - Guy C. Lloyd-Jones
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K
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9
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Neil B, Lucien F, Fensterbank L, Chauvier C. Transition-Metal-Free Silylation of Unactivated C(sp 2)–H Bonds with tert-Butyl-Substituted Silyldiazenes. ACS Catal 2021. [DOI: 10.1021/acscatal.1c03824] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Baptiste Neil
- Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, 4 Place Jussieu, 75252 CEDEX 05 Paris, France
| | - Franck Lucien
- Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, 4 Place Jussieu, 75252 CEDEX 05 Paris, France
| | - Louis Fensterbank
- Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, 4 Place Jussieu, 75252 CEDEX 05 Paris, France
| | - Clément Chauvier
- Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, 4 Place Jussieu, 75252 CEDEX 05 Paris, France
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10
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Minami Y, Hiyama T. Cross-coupling Reaction based on the Transformation of Trialkylsilyl Groups. J SYN ORG CHEM JPN 2021. [DOI: 10.5059/yukigoseikyokaishi.79.642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yasunori Minami
- Department of Materials and Chemistry, National Institute of Advanced Industrial Science and Technology (AIST)
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11
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Mechanism of Anion-Catalyzed C–H Silylation Using TMSCF3: Kinetically-Controlled CF3-Anionoid Partitioning As a Key Parameter. ACS Catal 2021. [DOI: 10.1021/acscatal.1c00033] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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12
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Li M, Wang T, An Z, Yan R. B(C 6F 5) 3-Catalyzed cyclization of alkynes: direct synthesis of 3-silyl heterocyclic compounds. Chem Commun (Camb) 2020; 56:11953-11956. [PMID: 33033821 DOI: 10.1039/d0cc04314a] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An efficient one-pot strategy for easy access to 3-silyl heterocyclic compounds was developed via a B(C6F5)3-catalyzed cycloaddition reaction of o-(1-alkynyl)(thio)anisoles or o-(1-alkynyl)-N-methylaniline. In this reaction, benzenethiophene, benzofuran or indole skeletons could be constructed by an intermolecular cyclization with diphenylsilane. This protocol elicited moderate-to-good yields with metal-free reaction systems.
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Affiliation(s)
- Mengxing Li
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu, China.
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13
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Nozawa-Kumada K. C-H Functionalization by Transition-metal-catalyst or in Situ Generated Base. YAKUGAKU ZASSHI 2019; 139:1243-1251. [DOI: 10.1248/yakushi.19-00146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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14
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Rand AW, Montgomery J. Catalytic reduction of aryl trialkylammonium salts to aryl silanes and arenes. Chem Sci 2019; 10:5338-5344. [PMID: 31191891 PMCID: PMC6540906 DOI: 10.1039/c9sc01083a] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 04/22/2019] [Indexed: 11/30/2022] Open
Abstract
Aryl trialkylammonium salts serve as versatile substrates for nickel-catalyzed reductions, allowing access to functionalized arenes and aryl silanes.
A new approach for the reduction of aryl ammonium salts to arenes or aryl silanes using nickel catalysis is reported. This method displays excellent ligand-controlled selectivity based on the N-heterocyclic carbene (NHC) ligand employed. Utilizing a large NHC in non-polar solvents generates aryl silanes, while small NHCs in polar solvents promote reduction to arenes. Several classes of aryl silanes can be accessed from simple aniline building blocks, including those useful for cross-couplings, oxidations, and halogenations. The reaction conditions are mild, functional group tolerant, and provide efficient access to a variety of benzene derivatives.
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Affiliation(s)
- Alexander W Rand
- Department of Chemistry , University of Michigan , 930 N. University Ave. , Ann Arbor , MI 48109-1055 , USA .
| | - John Montgomery
- Department of Chemistry , University of Michigan , 930 N. University Ave. , Ann Arbor , MI 48109-1055 , USA .
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15
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Johnston C, West TH, Dooley RE, Reid M, Jones AB, King EJ, Leach AG, Lloyd-Jones GC. Anion-Initiated Trifluoromethylation by TMSCF 3: Deconvolution of the Siliconate-Carbanion Dichotomy by Stopped-Flow NMR/IR. J Am Chem Soc 2018; 140:11112-11124. [PMID: 30080973 PMCID: PMC6133236 DOI: 10.1021/jacs.8b06777] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Indexed: 12/25/2022]
Abstract
The mechanism of CF3 transfer from R3SiCF3 (R = Me, Et, iPr) to ketones and aldehydes, initiated by M+X- (<0.004 to 10 mol %), has been investigated by analysis of kinetics (variable-ratio stopped-flow NMR and IR), 13C/2H KIEs, LFER, addition of ligands (18-c-6, crypt-222), and density functional theory calculations. The kinetics, reaction orders, and selectivity vary substantially with reagent (R3SiCF3) and initiator (M+X-). Traces of exogenous inhibitors present in the R3SiCF3 reagents, which vary substantially in proportion and identity between batches and suppliers, also affect the kinetics. Some reactions are complete in milliseconds, others take hours, and others stall before completion. Despite these differences, a general mechanism has been elucidated in which the product alkoxide and CF3- anion act as chain carriers in an anionic chain reaction. Silyl enol ether generation competes with 1,2-addition and involves protonation of CF3- by the α-C-H of the ketone and the OH of the enol. The overarching mechanism for trifluoromethylation by R3SiCF3, in which pentacoordinate siliconate intermediates are unable to directly transfer CF3- as a nucleophile or base, rationalizes why the turnover rate (per M+X- initiator) depends on the initial concentration (but not identity) of X-, the identity (but not concentration) of M+, the identity of the R3SiCF3 reagent, and the carbonyl/R3SiCF3 ratio. It also rationalizes which R3SiCF3 reagent effects the most rapid trifluoromethylation, for a specific M+X- initiator.
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Affiliation(s)
- Craig
P. Johnston
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, U.K.
| | - Thomas H. West
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, U.K.
| | - Ruth E. Dooley
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, U.K.
| | - Marc Reid
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, U.K.
| | - Ariana B. Jones
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, U.K.
| | - Edward J. King
- TgK
Scientific Limited, 7
Long’s Yard, St Margaret’s Street, Bradford-on-Avon, BA15 1DH, U.K.
| | - Andrew G. Leach
- School
of Pharmacy and Biomolecular Sciences, Liverpool
John Moores University, Byrom Street, Liverpool, L3 3AF, U.K.
| | - Guy C. Lloyd-Jones
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, U.K.
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16
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Komiyama T, Minami Y, Hiyama T. Copper-catalyzed Cross-coupling Reaction between Aryl(trialkyl)silanes and Alkyl Halides. CHEM LETT 2018. [DOI: 10.1246/cl.180426] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Takeshi Komiyama
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
| | - Yasunori Minami
- Research and Development Initiative, Chuo University, Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
| | - Tamejiro Hiyama
- Research and Development Initiative, Chuo University, Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
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