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Mroczyńska K, Dobrzańska L, Rafiński Z. Enantioselective synthesis of C3-functionalized 2,1-benzothiazine 2,2-dioxides by N-heterocyclic carbene catalysis. Chem Commun (Camb) 2024; 60:7176-7179. [PMID: 38904356 DOI: 10.1039/d4cc01754d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
We present herein an approach for the enantioselective C3-functionalization of 2,1-benzothiazine 2,2-dioxides using N-heterocyclic carbene (NHC) catalysis. Our method involves a sequence of [3+3] cycloaddition and ring-opening reactions with different N- and O-nucleophiles, followed by silylation. Overcoming the challenge of selectivity targeting the C3 position, this protocol demonstrates a broad substrate scope and high enantioselectivity. This marks a significant advancement in the field of NHC-catalyzed transformations.
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Affiliation(s)
- Karina Mroczyńska
- Nicolaus Copernicus University in Toruń, Faculty of Chemistry, 7 Gagarin Street, 87-100 Toruń, Poland.
| | - Liliana Dobrzańska
- Nicolaus Copernicus University in Toruń, Faculty of Chemistry, 7 Gagarin Street, 87-100 Toruń, Poland.
| | - Zbigniew Rafiński
- Nicolaus Copernicus University in Toruń, Faculty of Chemistry, 7 Gagarin Street, 87-100 Toruń, Poland.
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2
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Barańska I, Rafińska K, Rafiński Z. Enantioselective Synthesis of Highly Substituted Fluoroalkylated Benzopyranones and 3-Coumaranones via N-Heterocyclic Carbene-Catalyzed Intramolecular Annulations. J Org Chem 2023; 88:14339-14344. [PMID: 37793100 PMCID: PMC10594660 DOI: 10.1021/acs.joc.3c01099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Indexed: 10/06/2023]
Abstract
A highly enantioselective intramolecular NHC-catalyzed approach for the synthesis of fluoroalkylated benzopyranones and 3-coumaranones with all-carbon quaternary stereocenters is presented. This reaction is catalyzed by N-heterocyclic carbenes (NHCs) and involves annulation reactions between in situ generated acyl anion intermediates and highly substituted trifluoromethyl-β,β-disubstituted Michael acceptors. The method can also be extended to perfluoroalkyl homologues.
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Affiliation(s)
- Izabela Barańska
- Faculty of Chemistry, Nicolaus Copernicus University in Torun, 7 Gagarin Street, Torun 87-100, Poland
| | - Katarzyna Rafińska
- Faculty of Chemistry, Nicolaus Copernicus University in Torun, 7 Gagarin Street, Torun 87-100, Poland
| | - Zbigniew Rafiński
- Faculty of Chemistry, Nicolaus Copernicus University in Torun, 7 Gagarin Street, Torun 87-100, Poland
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G M, Sharma D, Dandela R, Dhayalan V. Synthetic Strategies of N-Heterocyclic Olefin (NHOs) and Their Recent Application of Organocatalytic Reactions and Beyond. Chemistry 2023:e202302106. [PMID: 37605950 DOI: 10.1002/chem.202302106] [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: 07/03/2023] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 08/23/2023]
Abstract
N-heterocyclic olefin (NHO) derivatives have an electron-rich as well as highly polarized carabon-carbon (C=C) double bond because of the electron-donating nature of nitrogen and sulphur atoms. While NHOs have been developing as novel organocatalysts and ligands for transition-metal complexes in various organic compound syntheses, different research groups are currently interested in preparing imidazole and triazolium-based chiral NHO catalysts. Some of them have been used for enantioselective organic transformations, but were still elusive. N-heterocyclic olefins, the alkylidene derivatives of N-heterocyclic carbenes (NHC), have shown promising results as effective promoters for numerous organic syntheses such as asymmetric catalysis, hydroborylation, hydrosilylation, reduction, CO2 sequestration, alkylation, cycloaddition, polymerization and the ring-opening reaction of aziridine and epoxides, esterification, C-F bond functionalization, amine coupling, trifluoromethyl thiolation, amination etc. NHOs catalysts with suitable structures can serve as a novel class of Lewis/Bronsted bases with strong basicity and high nucleophilicity properties.These facts strongly suggest their enormous chemical potential as sustainable catalysts for a wide variety of reactions in synthetic chemistry. The synthesis of NHOs and their properties are briefly reviewed in this article, along with a summary of the imidazole and triazole core of NHOs' most recent catalytic uses.
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Affiliation(s)
- Mahantesh G
- Department of Chemistry, National Institute of Technology Puducherry, Karaikal, 609609, Union Territory Puducherry, India
| | - Deepika Sharma
- Department of Industrial and Engineering Chemistry, Institute of Chemical Technology, Indian oil Odisha Campus, IIT, Kharagpur extension Centre Mouza Samantpuri, Bhubaneswar, 751013, Odisha, India
| | - Rambabu Dandela
- Department of Industrial and Engineering Chemistry, Institute of Chemical Technology, Indian oil Odisha Campus, IIT, Kharagpur extension Centre Mouza Samantpuri, Bhubaneswar, 751013, Odisha, India
| | - Vasudevan Dhayalan
- Department of Chemistry, National Institute of Technology Puducherry, Karaikal, 609609, Union Territory Puducherry, India
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Jabłoński M. Halogen Bond to Experimentally Significant N-Heterocyclic Carbenes (I, IMe 2, I iPr 2, I tBu 2, IPh 2, IMes 2, IDipp 2, IAd 2; I = Imidazol-2-ylidene). Int J Mol Sci 2023; 24:ijms24109057. [PMID: 37240403 DOI: 10.3390/ijms24109057] [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: 04/24/2023] [Revised: 05/15/2023] [Accepted: 05/18/2023] [Indexed: 05/28/2023] Open
Abstract
The subjects of the article are halogen bonds between either XCN or XCCH (X = Cl, Br, I) and the carbene carbon atom in imidazol-2-ylidene (I) or its derivatives (IR2) with experimentally significant and systematically increased R substituents at both nitrogen atoms: methyl = Me, iso-propyl = iPr, tert-butyl = tBu, phenyl = Ph, mesityl = Mes, 2,6-diisopropylphenyl = Dipp, 1-adamantyl = Ad. It is shown that the halogen bond strength increases in the order Cl < Br < I and the XCN molecule forms stronger complexes than XCCH. Of all the carbenes considered, IMes2 forms the strongest and also the shortest halogen bonds with an apogee for complex IMes2⋯ICN for which D0 = 18.71 kcal/mol and dC⋯I = 2.541 Å. In many cases, IDipp2 forms as strong halogen bonds as IMes2. Quite the opposite, although characterized by the greatest nucleophilicity, ItBu2 forms the weakest complexes (and the longest halogen bonds) if X ≠ Cl. While this finding can easily be attributed to the steric hindrance exerted by the highly branched tert-butyl groups, it appears that the presence of the four C-H⋯X hydrogen bonds may also be of importance here. Similar situation occurs in the case of complexes with IAd2.
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Affiliation(s)
- Mirosław Jabłoński
- Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Torun, Poland
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Jabłoński M. On the Coexistence of the Carbene⋯H-D Hydrogen Bond and Other Accompanying Interactions in Forty Dimers of N-Heterocyclic-Carbenes (I, IMe 2, I iPr 2, I tBu 2, IMes 2, IDipp 2, IAd 2; I = imidazol-2-ylidene) and Some Fundamental Proton Donors (HF, HCN, H 2O, MeOH, NH 3). Molecules 2022; 27:molecules27175712. [PMID: 36080481 PMCID: PMC9457876 DOI: 10.3390/molecules27175712] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/25/2022] [Accepted: 08/29/2022] [Indexed: 11/16/2022] Open
Abstract
The subject of research is forty dimers formed by imidazol-2-ylidene (I) or its derivative (IR2) obtained by replacing the hydrogen atoms in both N-H bonds with larger important and popular substituents of increasing complexity (methyl = Me, iso-propyl = iPr, tert-butyl = tBu, phenyl = Ph, mesityl = Mes, 2,6-diisopropylphenyl = Dipp, 1-adamantyl = Ad) and fundamental proton donor (HD) molecules (HF, HCN, H2O, MeOH, NH3). While the main goal is to characterize the generally dominant C⋯H-D hydrogen bond engaging a carbene carbon atom, an equally important issue is the often omitted analysis of the role of accompanying secondary interactions. Despite the often completely different binding possibilities of the considered carbenes, and especially HD molecules, several general trends are found. Namely, for a given carbene, the dissociation energy values of the IR2⋯HD dimers increase in the following order: NH3< H2O < HCN ≤ MeOH ≪ HF. Importantly, it is found that, for a given HD molecule, IDipp2 forms the strongest dimers. This is attributed to the multiplicity of various interactions accompanying the dominant C⋯H-D hydrogen bond. It is shown that substitution of hydrogen atoms in both N-H bonds of the imidazol-2-ylidene molecule by the investigated groups leads to stronger dimers with HF, HCN, H2O or MeOH. The presented results should contribute to increasing the knowledge about the carbene chemistry and the role of intermolecular interactions, including secondary ones.
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Affiliation(s)
- Mirosław Jabłoński
- Faculty of Chemistry, Nicolaus Copernicus University in Toruń, ul. Gagarina 7, 87-100 Toruń, Poland
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Jabłoński M. Theoretical Study of N-Heterocyclic-Carbene-ZnX 2 (X = H, Me, Et) Complexes. MATERIALS 2021; 14:ma14206147. [PMID: 34683739 PMCID: PMC8539904 DOI: 10.3390/ma14206147] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 09/24/2021] [Accepted: 10/12/2021] [Indexed: 11/16/2022]
Abstract
This article discusses the properties of as many as 30 carbene–ZnX2 (X = H, Me, Et) complexes featuring a zinc bond C⋯Zn. The group of carbenes is represented by imidazol-2-ylidene and its nine derivatives (labeled as IR), in which both hydrogen atoms of N-H bonds have been substituted by R groups with various spatial hindrances, from the smallest Me, iPr, tBu through Ph, Tol, and Xyl to the bulkiest Mes, Dipp, and Ad. The main goal is to study the relationship between type and size of R and X and both the strength of C⋯Zn and the torsional angle of the ZnX2 plane with respect to the plane of the imidazol-2-ylidene ring. Despite the considerable diversity of R and X, the range of dC⋯Zn is quite narrow: 2.12–2.20 Å. On the contrary, D0 is characterized by a fairly wide range of 18.5–27.4 kcal/mol. For the smallest carbenes, the ZnX2 molecule is either in the plane of the carbene or is only slightly twisted with respect to it. The twist angle becomes larger and more varied with the bulkier R. However, the value of this angle is not easy to predict because it results not only from the presence of steric effects but also from the possible presence of various interatomic interactions, such as dihydrogen bonds, tetrel bonds, agostic bonds, and hydrogen bonds. It has been shown that at least some of these interactions may have a non-negligible influence on the structure of the IR–ZnX2 complex. This fact should be taken into account in addition to the commonly discussed R⋯X steric repulsion.
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Affiliation(s)
- Mirosław Jabłoński
- Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń, Poland
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Dzieszkowski K, Słotwiński M, Rafińska K, Muzioł TM, Rafiński Z. NHC-catalyzed enantioselective C2-functionalization of 3-hydroxychromenones via α,β-unsaturated acyl azoliums. Chem Commun (Camb) 2021; 57:9999-10002. [PMID: 34490868 DOI: 10.1039/d1cc03708k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel synthetic method for enantioselective C2-functionalization of 3-hydroxychromenones promoted by N-heterocyclic carbenes via the formation of α,β-unsaturated acyl azolium intermediates, which occurs with Coates-Claisen rearrangement is established. This synthetic strategy enabled the rapid assembly of enantiomerically enriched δ-hydroxychromenone-derived esters/amides under mild conditions with good to excellent yields and broad substrate scope.
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Affiliation(s)
- Krzysztof Dzieszkowski
- Nicolaus Copernicus University in Torun, Faculty of Chemistry, 7 Gagarin Street, 87-100 Toruń, Poland.
| | - Michał Słotwiński
- Nicolaus Copernicus University in Torun, Faculty of Chemistry, 7 Gagarin Street, 87-100 Toruń, Poland.
| | - Katarzyna Rafińska
- Nicolaus Copernicus University in Torun, Faculty of Chemistry, 7 Gagarin Street, 87-100 Toruń, Poland.
| | - Tadeusz M Muzioł
- Nicolaus Copernicus University in Torun, Faculty of Chemistry, 7 Gagarin Street, 87-100 Toruń, Poland.
| | - Zbigniew Rafiński
- Nicolaus Copernicus University in Torun, Faculty of Chemistry, 7 Gagarin Street, 87-100 Toruń, Poland.
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Pavithra T, Devi ES, Maheswari CU. Recent Advances in N‐Heterocyclic Carbene Catalyzed Oxidative Cyclization for the Formation of Heterocycles. ASIAN J ORG CHEM 2021. [DOI: 10.1002/ajoc.202100289] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- T. Pavithra
- Department of Chemistry, School of Chemical and Biotechnology SASTRA Deemed University Thanjavur 613401 India
| | - E. Sankari Devi
- Department of Chemistry, School of Chemical and Biotechnology SASTRA Deemed University Thanjavur 613401 India
| | - C. Uma Maheswari
- Department of Chemistry, School of Chemical and Biotechnology SASTRA Deemed University Thanjavur 613401 India
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