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Sarigul Ozbek S, Teke Tuncel S, Erol Gunal S, Dogan I. Enantiodifferentiation of Thiohydantoin Derivatives by NMR in the Presence of Chiral Solvating Agent: (1R,2S)-Ephedrine and Chiral Symmetrical and Unsymmetrical Thioureas. Chirality 2025; 37:e70013. [PMID: 39844744 DOI: 10.1002/chir.70013] [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: 08/17/2024] [Revised: 12/06/2024] [Accepted: 12/23/2024] [Indexed: 01/24/2025]
Abstract
2-Thiohydantoin derivatives, including different substitutions at N-1 and C-5 (5-methyl-, 5-isopropyl-, 1-acetyl-5-methyl-, and 1-acetyl-5-isopropyl-) (1-4, respectively), were synthesized by the known literature methods. In these synthetic pathways, it was reported that enantiomerically pure 2-thiohydantions were obtained in the absence of any solvent via the reaction of L-amino acids with thiourea (1&2) and via the reaction of L-amino acids with NH4SCN and acetic anhydride (3&4). However, in this study, in contrary to the previous literature studies, racemic mixtures of 2-thiohydantoins were obtained although the same synthetic methods were used. The racemic nature of 2-thiohydantoin derivatives (1-4) was proved by using 1H NMR analysis in the presence of (1R,2S)-(-)-ephedrine as a chiral auxiliary. In addition, the enantiomers of 3&4 were also resolved on chiral stationary phases by HPLC analyses. Furthermore, newly synthesized unsymmetrical chiral thioureas (S-1&S-2) and previously synthesized symmetrical ones (SS-3&SS-4) were used as chiral solvating agent (CSA) for the enantiodiscrimination of the thiohydantoins (5&6), previously reported. Optimal CSA/substrate ratios were determined for the best enantiodiscrimination.
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Affiliation(s)
- Sevgi Sarigul Ozbek
- Faculty of Pharmacy, Department of Analytical Chemistry, Acıbadem Mehmet Ali Aydınlar University, Istanbul, Turkey
| | - Senel Teke Tuncel
- Department of Molecular Biology and Genetics, İstanbul Arel University, Istanbul, Turkey
| | - Sule Erol Gunal
- Faculty of Pharmacy, Department of Pharmaceutical Chemistry, İstanbul University-Cerrahpaşa, Istanbul, Turkey
| | - Ilknur Dogan
- Department of Chemistry, Bogazici University, Istanbul, Turkey
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2
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Spiaggia F, Uccello Barretta G, Iuliano A, Baldassari C, Aiello F, Balzano F. A Squaramide-Based Organocatalyst as a Novel Versatile Chiral Solvating Agent for Carboxylic Acids. Molecules 2024; 29:2389. [PMID: 38792248 PMCID: PMC11123912 DOI: 10.3390/molecules29102389] [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: 04/17/2024] [Revised: 05/03/2024] [Accepted: 05/15/2024] [Indexed: 05/26/2024] Open
Abstract
A squaramide-based organocatalyst for asymmetric Michael reactions has been tested as a chiral solvating agent (CSA) for 26 carboxylic acids and camphorsulfonic acid, encompassing amino acid derivatives, mandelic acid, as well as some of its analogs, propionic acids like profens (ketoprofen and ibuprofen), butanoic acids and others. In many cases remarkably high enantiodifferentiations at 1H, 13C and 19F nuclei were observed. The interaction likely involves a proton transfer from the acidic substrates to the tertiary amine sites of the organocatalyst, thus allowing for pre-solubilization of the organocatalyst (when a chloroform solution of the substrate is employed) or the simultaneous solubilization of both the catalyst and the substrate. DOSY experiments were employed to evaluate whether the catalyst-substrate ionic adduct was a tight one or not. ROESY experiments were employed to investigate the role of the squaramide unit in the adduct formation. A mechanism of interaction was proposed in accordance with the literature data.
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Affiliation(s)
- Fabio Spiaggia
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy; (A.I.); (C.B.); (F.B.)
| | - Gloria Uccello Barretta
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy; (A.I.); (C.B.); (F.B.)
| | - Anna Iuliano
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy; (A.I.); (C.B.); (F.B.)
| | - Carlo Baldassari
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy; (A.I.); (C.B.); (F.B.)
| | - Federica Aiello
- National Research Council, Institute for Chemical and Physical Processes (CNR-IPCF), Via G. Moruzzi 1, 56124 Pisa, Italy;
| | - Federica Balzano
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy; (A.I.); (C.B.); (F.B.)
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Mo MY, Wang XJ, Shen RZ, Hu CY, Li XC, Li GW, Liu LT. Enantiospecific Analysis of Carboxylic Acids Using Cinchona Alkaloid Dimers as Chiral Solvating Agents. Anal Chem 2024; 96:7487-7496. [PMID: 38695134 DOI: 10.1021/acs.analchem.4c00053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/15/2024]
Abstract
Cinchona alkaloid derivatives as Brønsted base catalysts have attracted considerable attention in the field of asymmetric catalysis. However, their potential application as chiral solvating agents has not been described. In this research, we investigated the use of the Cinchona alkaloid dimer, namely, (DHQ)2PHAL, as a chiral solvating agent for discerning various mandelic acid derivatives through 1H NMR spectroscopy. The addition of catalytic amounts of DMAP facilitated this process. Our experimental results demonstrate that dimeric (DHQ)2PHAL exhibits remarkable chiral discrimination properties regarding the diagnostic split protons of 1H NMR signals (including 24 examples, up to 0.321 ppm). Furthermore, it serves as an excellent chiral discriminating agent and provides good resolution for racemic chiral phosphoric acid as determined by 31P NMR spectroscopy. The quality of enantiodifferentiation has also been evaluated by means of the parameter "resolution (Rs)". Significantly, this class of CSAs based on (alkaloid)2linker systems with an azaaromatic linker can be directly employed, which is commercially available in an enantiopure form at very low cost and exhibits promising potential in determining the enantiopurity of α-hydroxy acids by chemoselective and biocatalytic reactions.
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Affiliation(s)
- Ming-Yang Mo
- School of Chemistry, Zhengzhou University, Zhengzhou, 450001, China
- College of Chemistry and Chemical Engineering, Henan Engineering Research Center for Green Synthesis of Pharmaceuticals, Shangqiu Normal University, Shangqiu 476000, China
| | - Xiao-Juan Wang
- College of Chemistry and Chemical Engineering, Henan Engineering Research Center for Green Synthesis of Pharmaceuticals, Shangqiu Normal University, Shangqiu 476000, China
| | - Ren-Zeng Shen
- College of Chemistry and Chemical Engineering, Henan Engineering Research Center for Green Synthesis of Pharmaceuticals, Shangqiu Normal University, Shangqiu 476000, China
| | - Chang-Yan Hu
- College of Chemistry and Chemical Engineering, Henan Engineering Research Center for Green Synthesis of Pharmaceuticals, Shangqiu Normal University, Shangqiu 476000, China
| | - Xue-Chun Li
- College of Chemistry and Chemical Engineering, Henan Engineering Research Center for Green Synthesis of Pharmaceuticals, Shangqiu Normal University, Shangqiu 476000, China
| | - Gao-Wei Li
- School of Chemistry, Zhengzhou University, Zhengzhou, 450001, China
- College of Chemistry and Chemical Engineering, Henan Engineering Research Center for Green Synthesis of Pharmaceuticals, Shangqiu Normal University, Shangqiu 476000, China
| | - Lan-Tao Liu
- School of Chemistry, Zhengzhou University, Zhengzhou, 450001, China
- College of Chemistry and Chemical Engineering, Henan Engineering Research Center for Green Synthesis of Pharmaceuticals, Shangqiu Normal University, Shangqiu 476000, China
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Wang Y, Zhao H, Yang C, Fang L, Zheng L, Lv H, Stavropoulos P, Ai L, Zhang J. Chiral Recognition of Chiral (Hetero)Cyclic Derivatives Probed by Tetraaza Macrocyclic Chiral Solvating Agents via 1H NMR Spectroscopy. Anal Chem 2024; 96:5188-5194. [PMID: 38506628 PMCID: PMC11492768 DOI: 10.1021/acs.analchem.3c05395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
In the field of chiral recognition, chiral cyclic organic compounds, especially heterocyclic organic compounds, have attracted little attention and have been rarely studied as chiral substrates by means of 1H NMR spectroscopy. In this paper, enantiomers of thiohydantoin derivatives, representing typical five-membered N,N-heterocycles, have been synthesized and utilized for assignment of absolute configuration and analysis of enantiomeric excess. All enantiomers have been successfully differentiated with the assistance of novel tetraaza macrocyclic chiral solvating agents (TAMCSAs) by 1H NMR spectroscopy. Surprisingly, unprecedented nonequivalent chemical shift values (up to 2.052 ppm) of the NH proton of substrates have been observed, a new milestone in the evaluation of enantiomers. To better understand the intermolecular interactions between host and guest, Job plots and theoretical calculations of (S)-G1 and (R)-G1 with TAMCSA 1a were investigated and revealed significant geometric differentiation between the diastereomers. In order to evaluate practical applications of the present systems in analyzing optical purity of chiral substrates, enantiomeric excesses of a typical substrate (G1) with different optical compositions in the presence of a representative TAMCSA (1a) can be accurately calculated based on the integration of the NH proton's signal peaks. Importantly, this work provides a significant breakthrough in exploring and developing the chiral recognition of chiral heterocyclic organic compounds by 1H NMR spectroscopy.
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Affiliation(s)
- Yu Wang
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Hongmei Zhao
- State Key Laboratory of Information Photonics and Communications, School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, P. R. China
| | - Chunxia Yang
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Lixia Fang
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Li Zheng
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Hehua Lv
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Pericles Stavropoulos
- Department of Chemistry, Missouri University of Science and Technology, Rolla, Missouri 65409, United States
| | - Lin Ai
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Jiaxin Zhang
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
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Xu L, Wang Q, Liu Y, Fu S, Zhao Y, Huang S, Huang B. 19F NMR enantiodiscrimination and diastereomeric purity determination of amino acids, dipeptides, and amines. Analyst 2023; 148:4548-4556. [PMID: 37594386 DOI: 10.1039/d3an00761h] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023]
Abstract
Chiral amino-group compounds are of significance for human health, such as biogenic amino acids (AAs), dipeptides, and even various drugs. Enantiospecific discrimination of these chiral compounds is vital in diagnosing diseases, identifying pathological biomarkers and enhancing pharmaceutical chemistry research. Here, we report a simple and rapid 19F NMR-based strategy to differentiate chiral AAs, dipeptides, and amines, that were derivatized with (R)-2-(2-fluorophenyl)-2-hydroxyacetic acid ((R)-2FHA). As a result, 19 proteinogenic AAs (37 isomers) as well as Gly could be concurrently resolved. Moreover, various mirror-image dipeptides, such as Ser-His, Leu-Leu, and Ala-Ala, were commendably recognized. Intriguingly, we found that the absolute configuration of AAs in the N-terminus of dipeptides decided the relative 19F chemical shifts between two enantiomers. Besides, the ability of this method for enantiodiscrimination was further demonstrated by non-AA amines, including aromatic and aliphatic amines, and even amines having chiral centers several carbons away from the amino-group. The structurally similar antibiotics, amoxicillin and ampicillin, were well discriminated. Furthermore, this method accurately determines the de or dr values of non-racemic mixtures. Therefore, our strategy provides an effective approach for 19F NMR-based enantiodiscrimination and diastereomeric purity determination of amino-group compounds.
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Affiliation(s)
- Lihua Xu
- Institute of Drug Discovery Technology, Ningbo University, Ningbo, 315211, P.R. China.
| | - Qiong Wang
- College of Chemistry, Shandong Normal University, Jinan, 250014, P.R. China
| | - Yan Liu
- Department of Chemical Biology, College of Chemistry and Chemical Engineering, and the Key Laboratory for Chemical Biology of Fujian Province, Xiamen University, Xiamen, 361005, P.R. China
| | - Songsen Fu
- Institute of Drug Discovery Technology, Ningbo University, Ningbo, 315211, P.R. China.
| | - Yufen Zhao
- Institute of Drug Discovery Technology, Ningbo University, Ningbo, 315211, P.R. China.
- Department of Chemical Biology, College of Chemistry and Chemical Engineering, and the Key Laboratory for Chemical Biology of Fujian Province, Xiamen University, Xiamen, 361005, P.R. China
- Key Lab of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University, Beijing, 100084, P.R. China
| | - Shaohua Huang
- Institute of Drug Discovery Technology, Ningbo University, Ningbo, 315211, P.R. China.
| | - Biling Huang
- Institute of Drug Discovery Technology, Ningbo University, Ningbo, 315211, P.R. China.
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Recchimurzo A, Balzano F, Uccello Barretta G, Gherardi L, Malanga M, Aiello F. Silylated-Acetylated Cyclodextrins as Chiral Sensors for the Enantiodiscrimination of Fluorinated Anesthetics. Molecules 2023; 28:molecules28062804. [PMID: 36985776 PMCID: PMC10058779 DOI: 10.3390/molecules28062804] [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: 03/01/2023] [Revised: 03/17/2023] [Accepted: 03/17/2023] [Indexed: 03/30/2023] Open
Abstract
Silylated-acetylated cyclodextrin (CD) derivatives have recently been investigated, via nuclear magnetic resonance (NMR) spectroscopy, as chiral sensors for substrates that are endowed and devoid of fluorine atoms, and the importance of Si-F interaction in the discrimination phenomena has been assessed. Here, the contributions of both superficial interactions and inclusion processes were further evaluated by extending the records to other chiral fluorinated substrates of interest for pharmaceutical applications. Non-equivalences were measured for both the 1H and 19F resonances in equimolar mixtures with the CDs; the promising results also supported the use of chiral sensors in sub-stoichiometric amounts. Finally, the occurrence of inclusion processes was evaluated by analyzing the intermolecular dipolar interactions by means of ROESY (Rotating-frame Overhauser Enhancement Spectroscopy) experiments. The study confirmed that the γCD derivative is the best chiral solvating agent for the fluorinated substrates investigated, likely due to the higher number of silyl moieties that can be involved in Si-F interactions. The contribution of inclusion processes to the enantiodiscrimination was also confirmed by comparison with the α- and β-analogues. Overall, the CD derivatives proved to be able to discriminate fluorinated substrates even when used in sub-stoichiometric amounts.
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Affiliation(s)
- Alessandra Recchimurzo
- Department of Chemistry and Industrial Chemistry, University of Pisa, via G. Moruzzi 13, 56124 Pisa, Italy
| | - Federica Balzano
- Department of Chemistry and Industrial Chemistry, University of Pisa, via G. Moruzzi 13, 56124 Pisa, Italy
| | - Gloria Uccello Barretta
- Department of Chemistry and Industrial Chemistry, University of Pisa, via G. Moruzzi 13, 56124 Pisa, Italy
| | - Luca Gherardi
- Department of Chemistry and Industrial Chemistry, University of Pisa, via G. Moruzzi 13, 56124 Pisa, Italy
| | - Milo Malanga
- CycloLab, Cyclodextrin R&D Ltd., Illatos út. 7, H-1097 Budapest, Hungary
| | - Federica Aiello
- National Research Council, Institute for Chemical and Physical Processes (CNR-IPCF), via G. Moruzzi 1, 56124 Pisa, Italy
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