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Rkein B, Manneveau M, Noël-Duchesneau L, Pasturaud K, Durandetti M, Legros J, Lakhdar S, Chataigner I. How electrophilic are 3-nitroindoles? Mechanistic investigations and application to a reagentless (4+2) cycloaddition. Chem Commun (Camb) 2021; 57:10071-10074. [PMID: 34515263 DOI: 10.1039/d1cc04074j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The electrophilicity of 4 different 3-nitroindole derivatives has been evaluated by Mayr's linear free energy relationship (log k(20 °C) = sN(E + N)) and reveals unexpected values for aromatic compounds, in the nitrostyrene range. 3-Nitroindoles are sufficiently electrophilic to interact with a common diene namely the Danishefsky's diene at room temperature, in the absence of any activator, to furnish smoothly the dearomatized (4+2) cycloadducts in good yields.
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Affiliation(s)
- Batoul Rkein
- Normandie Univ., UNIROUEN, CNRS, INSA Rouen, COBRA, 76000 Rouen, France.
| | - Maxime Manneveau
- Normandie Univ., UNIROUEN, CNRS, INSA Rouen, COBRA, 76000 Rouen, France.
| | | | - Karine Pasturaud
- Normandie Univ., UNIROUEN, CNRS, INSA Rouen, COBRA, 76000 Rouen, France.
| | - Muriel Durandetti
- Normandie Univ., UNIROUEN, CNRS, INSA Rouen, COBRA, 76000 Rouen, France.
| | - Julien Legros
- Normandie Univ., UNIROUEN, CNRS, INSA Rouen, COBRA, 76000 Rouen, France.
| | - Sami Lakhdar
- Normandie Univ., ENSICAEN, Unicaen, CNRS, LCMT, 14000 Caen, France.,Université Paul Sabatier, Laboratoire Hétérochimie Fondamentale et Appliquée (LHFA, UMR 5069), 118 Route de Narbonne, 31062, Toulouse Cedex 09, France.
| | - Isabelle Chataigner
- Normandie Univ., UNIROUEN, CNRS, INSA Rouen, COBRA, 76000 Rouen, France. .,Sorbonne Université, CNRS, Laboratoire de Chimie Théorique, LCT UMR7616, 75005 Paris, France
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2
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Kang Q, Lin Y, Li Y, Xu L, Li K, Shi H. Catalytic S
N
Ar Hydroxylation and Alkoxylation of Aryl Fluorides. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202106440] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Qi‐Kai Kang
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province School of Science Westlake University 18 Shilongshan Road Hangzhou 310024 Zhejiang Province China
- Institute of Natural Sciences Westlake Institute for Advanced Study 18 Shilongshan Road Hangzhou 310024 Zhejiang Province China
| | - Yunzhi Lin
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province School of Science Westlake University 18 Shilongshan Road Hangzhou 310024 Zhejiang Province China
| | - Yuntong Li
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province School of Science Westlake University 18 Shilongshan Road Hangzhou 310024 Zhejiang Province China
| | - Lun Xu
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province School of Science Westlake University 18 Shilongshan Road Hangzhou 310024 Zhejiang Province China
| | - Ke Li
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province School of Science Westlake University 18 Shilongshan Road Hangzhou 310024 Zhejiang Province China
- Institute of Natural Sciences Westlake Institute for Advanced Study 18 Shilongshan Road Hangzhou 310024 Zhejiang Province China
| | - Hang Shi
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province School of Science Westlake University 18 Shilongshan Road Hangzhou 310024 Zhejiang Province China
- Institute of Natural Sciences Westlake Institute for Advanced Study 18 Shilongshan Road Hangzhou 310024 Zhejiang Province China
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3
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Kang QK, Lin Y, Li Y, Xu L, Li K, Shi H. Catalytic S N Ar Hydroxylation and Alkoxylation of Aryl Fluorides. Angew Chem Int Ed Engl 2021; 60:20391-20399. [PMID: 34263536 DOI: 10.1002/anie.202106440] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 07/08/2021] [Indexed: 12/14/2022]
Abstract
Nucleophilic aromatic substitution (SN Ar) is a powerful strategy for incorporating a heteroatom into an aromatic ring by displacement of a leaving group with a nucleophile, but this method is limited to electron-deficient arenes. We have now established a reliable method for accessing phenols and phenyl alkyl ethers via catalytic SN Ar reactions. The method is applicable to a broad array of electron-rich and neutral aryl fluorides, which are inert under classical SN Ar conditions. Although the mechanism of SN Ar reactions involving metal arene complexes is hypothesized to involve a stepwise pathway (addition followed by elimination), experimental data that support this hypothesis is still under exploration. Mechanistic studies and DFT calculations suggest either a stepwise or stepwise-like energy profile. Notably, we isolated a rhodium η5 -cyclohexadienyl complex intermediate with an sp3 -hybridized carbon bearing both a nucleophile and a leaving group.
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Affiliation(s)
- Qi-Kai Kang
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China.,Institute of Natural Sciences, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China
| | - Yunzhi Lin
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China
| | - Yuntong Li
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China
| | - Lun Xu
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China
| | - Ke Li
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China.,Institute of Natural Sciences, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China
| | - Hang Shi
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China.,Institute of Natural Sciences, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China
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Li X, Wei D, Li Z. Theoretical Study on DBU-Catalyzed Insertion of Isatins into Aryl Difluoronitromethyl Ketones: A Case for Predicting Chemoselectivity Using Electrophilic Parr Function. ACS OMEGA 2017; 2:7029-7038. [PMID: 31457285 PMCID: PMC6645149 DOI: 10.1021/acsomega.7b00907] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 10/05/2017] [Indexed: 06/10/2023]
Abstract
The possible mechanisms of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-catalyzed chemoselective insertion of N-methyl isatin into aryl difluoronitromethyl ketone to synthesize 3,3-disubstituted and 2,2-disubstituted oxindoles have been studied in this work. As revealed by calculated results, the reaction occurs via two competing paths, including α and β carbonyl paths, and each path contains five steps, that is, nucleophilic addition of DBU to ketone, C-C bond cleavage affording difluoromethylnitrate anion and phenylcarbonyl-DBU cation, nucleophilic addition of difluoromethylnitrate anion to carbonyl carbon of N-methyl isatin, acyl transfer process, and dissociation of DBU and product. The computational results suggest that nucleophilic additions on different carbonyl carbons of N-methyl isatin via α and β carbonyl paths would lead to different products in the third step, and β carbonyl path associated with the main product 3,3-disubstituted oxindole is more energetically favorable, which is consistent with the experimental observations. Noteworthy, electrophilic Parr function can be successfully applied for exactly predicting the activity of reaction site and reasonably explaining the chemoselectivity. In addition, the distortion/interaction and noncovalent interaction analyses show that much more hydrogen bond interactions should be responsible for the lower energy of the transition state associated with β carbonyl path. The obtained insights would be valuable for the rational design of efficient organocatalysts for this kind of reactions with high selectivities.
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Blaszczyk AJ, Wang B, Silakov A, Ho JV, Booker SJ. Efficient methylation of C2 in l-tryptophan by the cobalamin-dependent radical S-adenosylmethionine methylase TsrM requires an unmodified N1 amine. J Biol Chem 2017; 292:15456-15467. [PMID: 28747433 PMCID: PMC5602403 DOI: 10.1074/jbc.m117.778548] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 07/20/2017] [Indexed: 11/06/2022] Open
Abstract
TsrM catalyzes the methylation of C2 in l-tryptophan (Trp). This reaction is the first step in the biosynthesis of the quinaldic acid moiety of the thiopeptide antibiotic thiostrepton, which exhibits potent activity against Gram-positive pathogens. TsrM is a member of the radical S-adenosylmethionine (SAM) superfamily of enzymes, but it does not catalyze the formation of 5'-deoxyadenosin-5'-yl or any other SAM-derived radical. In addition to a [4Fe-4S] cluster, TsrM contains a cobalamin cofactor that serves as an intermediate methyl carrier in its reaction. However, how this cofactor donates a methyl moiety to the Trp substrate is unknown. Here, we showed that the unmodified N1 position of Trp is important for turnover and that 1-thia-Trp and 1-oxa-Trp serve as competitive inhibitors. We also showed that β-cyclopropyl-Trp undergoes C2 methylation in the absence of cyclopropyl ring opening, disfavoring mechanisms that involve unpaired electron density at C3 of the indole ring. Moreover, we showed that all other indole-substituted analogs of Trp undergo methylation at varying but measurable rates and that the analog 7-aza-Trp, which is expected to temper the nucleophilicity of C2 in Trp, is a very poor substrate. Last, no formation of cob(II)alamin or substrate radicals was observed during the reaction with Trp or any molecule within a tested panel of Trp analogs. In summary, our results are most consistent with a mechanism that involves two polar nucleophilic displacements, the second of which requires deprotonation of the indole nitrogen in Trp during its attack on methylcobalamin.
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Affiliation(s)
| | - Bo Wang
- the Department of Chemistry, and
| | | | | | - Squire J Booker
- From the Department of Biochemistry and Molecular Biology,
- the Department of Chemistry, and
- the Howard Hughes Medical Institute, The Pennsylvania State University, University Park, Pennsylvania 16802
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