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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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Balzano F, Iuliano A, Uccello-Barretta G, Zullo V. Renewable Resources for Enantiodiscrimination: Chiral Solvating Agents for NMR Spectroscopy from Isomannide and Isosorbide. J Org Chem 2022; 87:12698-12709. [PMID: 36075050 PMCID: PMC9552179 DOI: 10.1021/acs.joc.2c01244] [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: 11/28/2022]
Abstract
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A new family of chiral selectors was synthesized in a
single synthetic
step with yields up to 84% starting from isomannide and isosorbide.
Mono- or disubstituted carbamate derivatives were obtained by reacting
the isohexides with electron-donating arylisocyanate (3,5-dimethylphenyl-
or 3,5-dimethoxyphenyl-) and electron-withdrawing arylisocyanate (3,5-bis(trifluoromethyl)phenyl-)
groups to test opposite electronic effects on enantiodifferentiation.
Deeper chiral pockets and derivatives with more acidic protons were
obtained by derivatization with 1-naphthylisocyanate and p-toluenesulfonylisocyanate, respectively. All compounds were
tested as chiral solvating agents (CSAs) in 1H NMR experiments
with rac-N-3,5-dinitrobenzoylphenylglycine
methyl ester in order to determine the influence of different structural
features on the enantiodiscrimination capabilities. Some selected
compounds were tested with other racemic analytes, still leading to
enantiodiscrimination. The enantiodiscrimination conditions were then
optimized for the best CSA/analyte couple. Finally, a 2D- and 1D-NMR
study was performed employing the best performing CSA with the two
enantiomers of the selected analyte, aiming to determine the enantiodiscrimination
mechanism, the stoichiometry of interaction, and the complexation
constant.
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Affiliation(s)
- Federica Balzano
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Giuseppe Moruzzi, 13, 56124 Pisa, Italy
| | - Anna Iuliano
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Giuseppe Moruzzi, 13, 56124 Pisa, Italy
| | - Gloria Uccello-Barretta
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Giuseppe Moruzzi, 13, 56124 Pisa, Italy
| | - Valerio Zullo
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Giuseppe Moruzzi, 13, 56124 Pisa, Italy
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Peluso P, Chankvetadze B. Recognition in the Domain of Molecular Chirality: From Noncovalent Interactions to Separation of Enantiomers. Chem Rev 2022; 122:13235-13400. [PMID: 35917234 DOI: 10.1021/acs.chemrev.1c00846] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
It is not a coincidence that both chirality and noncovalent interactions are ubiquitous in nature and synthetic molecular systems. Noncovalent interactivity between chiral molecules underlies enantioselective recognition as a fundamental phenomenon regulating life and human activities. Thus, noncovalent interactions represent the narrative thread of a fascinating story which goes across several disciplines of medical, chemical, physical, biological, and other natural sciences. This review has been conceived with the awareness that a modern attitude toward molecular chirality and its consequences needs to be founded on multidisciplinary approaches to disclose the molecular basis of essential enantioselective phenomena in the domain of chemical, physical, and life sciences. With the primary aim of discussing this topic in an integrated way, a comprehensive pool of rational and systematic multidisciplinary information is provided, which concerns the fundamentals of chirality, a description of noncovalent interactions, and their implications in enantioselective processes occurring in different contexts. A specific focus is devoted to enantioselection in chromatography and electromigration techniques because of their unique feature as "multistep" processes. A second motivation for writing this review is to make a clear statement about the state of the art, the tools we have at our disposal, and what is still missing to fully understand the mechanisms underlying enantioselective recognition.
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Affiliation(s)
- Paola Peluso
- Istituto di Chimica Biomolecolare ICB, CNR, Sede secondaria di Sassari, Traversa La Crucca 3, Regione Baldinca, Li Punti, I-07100 Sassari, Italy
| | - Bezhan Chankvetadze
- Institute of Physical and Analytical Chemistry, School of Exact and Natural Sciences, Tbilisi State University, Chavchavadze Avenue 3, 0179 Tbilisi, Georgia
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Zhang H, Zhao H, Wen J, Zhang Z, Stavropoulos P, Li Y, Ai L, Zhang J. Discrimination of enantiomers of amides with two stereogenic centers enabled by chiral bisthiourea derivatives using 1H NMR spectroscopy. Org Biomol Chem 2021; 19:6697-6706. [PMID: 34296731 DOI: 10.1039/d1ob00742d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Enantiomers of a few new amides containing two stereogenic centers have been derived from d- and l-α-amino acids as guests for chiral recognition by 1H NMR spectroscopy. A variety of chiral amides with two or more stereogenic centers often exist in the products of catalytic asymmetric synthesis, natural products or their total synthetic products, and chiral drugs. It would be a challenging and meaningful work to explore their chiral recognition. For this purpose, a class of novel chiral bisthiourea derivatives 1-9 has been synthesized from (1S,2S)-(+)-1,2-diaminocyclohexane, d-α-amino acids, and isothiocyanates as chiral solvating agents (CSAs). CSAs 1-9 proved to afford better chiral discriminating results towards most amides with two stereogenic centers, which have been rarely studied as chiral substrates by 1H NMR spectroscopy. In particular, CSAs 7, 8 and 9, featuring 3,5-bis(trifluoromethyl)benzene residues, exhibit outstanding chiral discriminating capabilities towards all amides, providing well-separated 1H NMR signals and sufficiently large nonequivalent chemical shifts. To test their practical application in the determination of enantiomeric excess, 1H NMR spectra of chiral amides (G16) with different optical purities were measured in the presence of CSAs 7 and 8, respectively. Their ee values (up to 90%) were accurately calculated by the integration of the NH proton of the CONHPh group of G16. To better understand the chiral discriminating behavior, Job plots of (±)-G16 with CSA 7 and (±)-G17 with CSA 8 and the association constants (Ka) of (S,R)-G16 and (R,S)-G16 with CSA 7 were evaluated, respectively. In order to further reveal any underlying intermolecular hydrogen bonding interactions, theoretical calculations of the enantiomers of (S,R)-G16 and (R,S)-G16 with CSA 7 were performed by means of the hybrid density functional theory (B3LYP) with the standard basis sets of 3-21G of the Gaussian 03 program, respectively.
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Affiliation(s)
- Hanchang Zhang
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.
| | - Hongmei Zhao
- State Key Laboratory of Information Photonics and Optical Communications, School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, P. R. China
| | - Jie Wen
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.
| | - Zhanbin Zhang
- 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, USA
| | - Yanlin Li
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.
| | - 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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Li GW, Wang XJ, Cui DD, Zhang YF, Xu RY, Shi SH, Liu LT, Wang MC, Liu HM, Lei XX. Azaheterocyclic diphenylmethanol chiral solvating agents for the NMR chiral discrimination of alpha-substituted carboxylic acids. RSC Adv 2020; 10:34605-34611. [PMID: 35514411 PMCID: PMC9056771 DOI: 10.1039/d0ra06312f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 08/24/2020] [Indexed: 12/02/2022] Open
Abstract
A series of small-membered heterocycle probes, so-called azaheterocycle-containing diphenylmethanol chiral solvating agents (CSAs), have been developed for NMR enantiodiscrimination. These chiral sensors were readily synthesized were inexpensive and efficiently used for the chiral analysis of alpha-substituted carboxylic acids. The sensing method was operationally simple and the processing was straightforward. Notably, we propose (S)-aziridinyl diphenylmethanol as a promising CSA, which has excellent chiral discriminating properties and offers multiple detectable possibilities pertaining to the 1H NMR signals of diagnostic split protons (including 25 examples, up to 0.194 ppm, 77.6 Hz). Its ability to detect the molecular recognition of fluorinated carboxylic acids were further investigated, with a good level of discrimination via the 19F NMR spectroscopic analysis. In addition, an accurate enantiomeric excess (ee) analysis of the p-methoxyl-mandelic acid with different optical compositions have been calculated based on the integration of well-separated proton signals. Chiral azaheterocycle-containing diphenylmethanols with multiple hydrogen-bonding sites were described and used as NMR chiral solvating agents (CSAs). Highly resolved NMR spectra can be obtained directly in the NMR tube.![]()
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Affiliation(s)
- Gao-Wei Li
- College of Chemistry and Chemical Engineering and Henan Engineering Laboratory of Green Synthesis for Pharmaceuticals, Shangqiu Normal University Shangqiu 476000 P. R. China .,School of Pharmaceutical Sciences, Zhengzhou University Zhengzhou 450001 P. R. China
| | - Xiao-Juan Wang
- College of Chemistry and Chemical Engineering and Henan Engineering Laboratory of Green Synthesis for Pharmaceuticals, Shangqiu Normal University Shangqiu 476000 P. R. China
| | - Dan-Dan Cui
- College of Chemistry and Chemical Engineering and Henan Engineering Laboratory of Green Synthesis for Pharmaceuticals, Shangqiu Normal University Shangqiu 476000 P. R. China
| | - Yu-Fei Zhang
- College of Chemistry and Chemical Engineering and Henan Engineering Laboratory of Green Synthesis for Pharmaceuticals, Shangqiu Normal University Shangqiu 476000 P. R. China
| | - Rong-Yao Xu
- College of Chemistry and Chemical Engineering and Henan Engineering Laboratory of Green Synthesis for Pharmaceuticals, Shangqiu Normal University Shangqiu 476000 P. R. China
| | - Shuai-Hua Shi
- College of Chemistry and Chemical Engineering and Henan Engineering Laboratory of Green Synthesis for Pharmaceuticals, Shangqiu Normal University Shangqiu 476000 P. R. China
| | - Lan-Tao Liu
- College of Chemistry and Chemical Engineering and Henan Engineering Laboratory of Green Synthesis for Pharmaceuticals, Shangqiu Normal University Shangqiu 476000 P. R. China
| | - Min-Can Wang
- School of Pharmaceutical Sciences, Zhengzhou University Zhengzhou 450001 P. R. China
| | - Hong-Min Liu
- School of Pharmaceutical Sciences, Zhengzhou University Zhengzhou 450001 P. R. China
| | - Xin-Xiang Lei
- School of Pharmaceutical Sciences, South-Central University for Nationalities Wuhan 430074 P. R. China
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Li G, Ma M, Wang G, Wang X, Lei X. Efficient Enantiodifferentiation of Carboxylic Acids Using BINOL-Based Amino Alcohol as a Chiral NMR Solvating Agent. Front Chem 2020; 8:336. [PMID: 32432082 PMCID: PMC7213237 DOI: 10.3389/fchem.2020.00336] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 04/01/2020] [Indexed: 12/30/2022] Open
Abstract
A new optically active BINOL-amino alcohol has been designed and synthesized in a good yield and applied as chiral nuclear magnetic resonance (NMR) solvating agent for enantioselective recognition. Analysis by 1H NMR spectroscopy demonstrated that it has excellent enantiodifferentiation properties toward carboxylic acids and non-steroidal anti-inflammatory drugs (14 examples). The non-equivalent chemical shifts (up to 0.641 ppm) of various mandelic acids were evaluated by the reliable peak of well-resolved 1H NMR signals. In addition, enantiomeric excesses of the ortho-chloro-mandelic acid with different enantiomeric ratio were calculated based on integration of proton well-separated splitting signals.
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Affiliation(s)
- Gaowei Li
- College of Chemistry and Chemical Engineering, Shangqiu Normal University, Shangqiu, China
| | - Minshan Ma
- School of Pharmaceutical Sciences, South Central University for Nationalities, Wuhan, China
| | - Guifang Wang
- School of Pharmaceutical Sciences, South Central University for Nationalities, Wuhan, China
| | - Xiaojuan Wang
- College of Chemistry and Chemical Engineering, Shangqiu Normal University, Shangqiu, China
| | - Xinxiang Lei
- School of Pharmaceutical Sciences, South Central University for Nationalities, Wuhan, China
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Jang S, Kim H. Chiral 1H NMR Analysis of Carbonyl Compounds Enabled by Cationic Cobalt Complex. Org Lett 2020; 22:4185-4189. [DOI: 10.1021/acs.orglett.0c01256] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Sumin Jang
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Hyunwoo Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
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Enantiodiscrimination of carboxylic acids using single enantiomer thioureas as chiral solvating agents. Tetrahedron 2020. [DOI: 10.1016/j.tet.2020.131141] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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