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Mykhailiuk PK. Fluorine-Containing Prolines: Synthetic Strategies, Applications, and Opportunities. J Org Chem 2022; 87:6961-7005. [PMID: 35175772 DOI: 10.1021/acs.joc.1c02956] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Fluorinated prolines play an important role in peptide studies, protein engineering, medicinal chemistry, drug discovery, and agrochemistry. Since the first synthesis of 4-fluoroprolines by Gottlieb and Witkop in 1965, their popularity started to grow exponentially. For example, during the past two decades, all isomeric trifluoromethyl-substituted prolines have been synthesized. In this Perspective, chemical properties and applications of fluorinated prolines are discussed. Synthetic approaches to all known fluorine-containing prolines are also discussed and analyzed. This analysis unexpectedly revealed an unsolved problem: in strict contrast to fluoro- and trifluoromethyl-substituted prolines, the corresponding analogues with fluoromethyl and difluoromethyl groups are mostly unknown. At the end of the paper, structures of several interesting, yet unknown, fluorinated prolines are disclosed─a good opportunity for chemists to make them.
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Pollastrini M, Lipparini F, Pasquinelli L, Balzano F, Barretta GU, Pescitelli G, Angelici G. A Proline Mimetic for the Design of New Stable Secondary Structures: Solvent-Dependent Amide Bond Isomerization of ( S)-Indoline-2-carboxylic Acid Derivatives. J Org Chem 2021; 86:7946-7954. [PMID: 34080867 PMCID: PMC8456495 DOI: 10.1021/acs.joc.1c00184] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Indexed: 12/22/2022]
Abstract
A thorough experimental and computational study on the conformational properties of (S)-indoline-2-carboxylic acid derivatives has been conducted. Methyl (S)-1-acetylindoline-2-carboxylate, both a mimetic of proline and phenylalanine, shows a remarkable tendency toward the cis amide isomer when dissolved in polar solvents. This behavior is opposite to the general preference of proline for the trans isomer, making indoline-2-carboxylic acid a good candidate for the design of different secondary structures and new materials.
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Affiliation(s)
- Matteo Pollastrini
- Dipartimento di Chimica e Chimica Industriale,
Università di Pisa, Via G. Moruzzi 13, 56124 Pisa,
Italy
| | - Filippo Lipparini
- Dipartimento di Chimica e Chimica Industriale,
Università di Pisa, Via G. Moruzzi 13, 56124 Pisa,
Italy
| | - Luca Pasquinelli
- Dipartimento di Chimica e Chimica Industriale,
Università di Pisa, Via G. Moruzzi 13, 56124 Pisa,
Italy
| | - Federica Balzano
- Dipartimento di Chimica e Chimica Industriale,
Università di Pisa, Via G. Moruzzi 13, 56124 Pisa,
Italy
| | - Gloria Uccello Barretta
- Dipartimento di Chimica e Chimica Industriale,
Università di Pisa, Via G. Moruzzi 13, 56124 Pisa,
Italy
| | - Gennaro Pescitelli
- Dipartimento di Chimica e Chimica Industriale,
Università di Pisa, Via G. Moruzzi 13, 56124 Pisa,
Italy
| | - Gaetano Angelici
- Dipartimento di Chimica e Chimica Industriale,
Università di Pisa, Via G. Moruzzi 13, 56124 Pisa,
Italy
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Mondal R, Agbaria M, Nairoukh Z. Fluorinated Rings: Conformation and Application. Chemistry 2021; 27:7193-7213. [PMID: 33512034 DOI: 10.1002/chem.202005425] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Indexed: 12/16/2022]
Abstract
The introduction of fluorine atoms into molecules and materials across many fields of academic and industrial research is now commonplace, owing to their unique properties. A particularly interesting feature is the impact of fluorine substitution on the relative orientation of a C-F bond when incorporated into organic molecules. In this Review, we will be discussing the conformational behavior of fluorinated aliphatic carbo- and heterocyclic systems. The conformational preference of each system is associated with various interactions introduced by fluorine substitution such as charge-dipole, dipole-dipole, and hyperconjugative interactions. The contribution of each interaction on the stabilization of the fluorinated alicyclic system, which manifests itself in low conformations, will be discussed in detail. The novelty of this feature will be demonstrated by presenting the most recent applications.
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Affiliation(s)
- Rajarshi Mondal
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem, 9190401, Israel
| | - Mohamed Agbaria
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem, 9190401, Israel
| | - Zackaria Nairoukh
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem, 9190401, Israel
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Levterov VV, Michurin O, Borysko PO, Zozulya S, Sadkova IV, Tolmachev AA, Mykhailiuk PK. Photochemical In-Flow Synthesis of 2,4-Methanopyrrolidines: Pyrrolidine Analogues with Improved Water Solubility and Reduced Lipophilicity. J Org Chem 2018; 83:14350-14361. [PMID: 30358395 DOI: 10.1021/acs.joc.8b02071] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A practical synthesis of 2,4-methanopyrrolidines was elaborated. The key synthetic step was an intramolecular photochemical [2 + 2]-cycloaddition of an acrylic acid derivative in flow. In spite of a higher molecular weight, 2,4-methanopyrrolidines were shown to have higher solubility in water and lower lipophilicity than pyrrolidines, important characteristics of bioactive molecules in drug design.
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Affiliation(s)
- Vadym V Levterov
- Enamine, Ltd. , Chervonotkatska 78 , Kyiv 02094 , Ukraine (www.enamine.net)
| | - Oleg Michurin
- Enamine, Ltd. , Chervonotkatska 78 , Kyiv 02094 , Ukraine (www.enamine.net)
| | - Petro O Borysko
- Bienta, Chervonotkatska 78 , Kyiv 02094 , Ukraine (www.bienta.net)
| | - Sergey Zozulya
- Bienta, Chervonotkatska 78 , Kyiv 02094 , Ukraine (www.bienta.net)
| | - Iryna V Sadkova
- Enamine, Ltd. , Chervonotkatska 78 , Kyiv 02094 , Ukraine (www.enamine.net)
| | - Andrey A Tolmachev
- Enamine, Ltd. , Chervonotkatska 78 , Kyiv 02094 , Ukraine (www.enamine.net).,Department of Chemistry , Taras Shevchenko National University of Kyiv , Volodymyrska 64 , Kyiv 01601 , Ukraine (www.mykhailiukchem.org)
| | - Pavel K Mykhailiuk
- Enamine, Ltd. , Chervonotkatska 78 , Kyiv 02094 , Ukraine (www.enamine.net).,Department of Chemistry , Taras Shevchenko National University of Kyiv , Volodymyrska 64 , Kyiv 01601 , Ukraine (www.mykhailiukchem.org)
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Chatgilialoglu C, Ferreri C, Landais Y, Timokhin VI. Thirty Years of (TMS)3SiH: A Milestone in Radical-Based Synthetic Chemistry. Chem Rev 2018; 118:6516-6572. [DOI: 10.1021/acs.chemrev.8b00109] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
| | - Carla Ferreri
- ISOF, Consiglio Nazionale delle Ricerche, Via P. Gobetti 101, 40129 Bologna, Italy
| | - Yannick Landais
- University of Bordeaux, Institute of Molecular Sciences, UMR-CNRS 5255, 351 cours de la libération, 33405 Talence Cedex, France
| | - Vitaliy I. Timokhin
- Department of Biochemistry, University of Wisconsin-Madison, 1552 University Avenue, Madison, Wisconsin 53726, United States
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Abstract
The carbonyl group holds a prominent position in chemistry and biology not only because it allows diverse transformations but also because it supports key intermolecular interactions, including hydrogen bonding. More recently, carbonyl groups have been found to interact with a variety of nucleophiles, including other carbonyl groups, in what we have termed an n→π* interaction. In an n→π* interaction, a nucleophile donates lone-pair (n) electron density into the empty π* orbital of a nearby carbonyl group. Mixing of these orbitals releases energy, resulting in an attractive interaction. Hints of such interactions were evident in small-molecule crystal structures as early as the 1970s, but not until 2001 was the role of such interactions articulated clearly. These non-covalent interactions were first discovered during investigations into the thermostability of the proline-rich protein collagen, which achieves a robust structure despite a relatively low potential for hydrogen bonding. It was found that by modulating the distance between two carbonyl groups in the peptide backbone, one could alter the conformational preferences of a peptide bond to proline. Specifically, only the trans conformation of a peptide bond to proline allows for an attractive interaction with an adjacent carbonyl group, so when one increases the proximity of the two carbonyl groups, one enhances their interaction and promotes the trans conformation of the peptide bond, which increases the thermostability of collagen. More recently, attention has been paid to the nature of these interactions. Some have argued that rather than resulting from electron donation, carbonyl interactions are a particular example of dipolar interactions that are well-approximated by classical mechanics. However, experimental evidence has demonstrated otherwise. Numerous examples now exist where an increase in the dipole moment of a carbonyl group decreases the strength of its interactions with other carbonyl groups, demonstrating unequivocally that a dipolar mechanism is insufficient to describe these interactions. Rather, these interactions have important quantum-mechanical character that can be evaluated through careful experimental analysis and judicious use of computation. Although individual n→π* interactions are relatively weak (∼0.3-0.7 kcal/mol), the ubiquity of carbonyl groups across chemistry and biology gives the n→π* interaction broad impact. In particular, the n→π* interaction is likely to play an important role in dictating protein structure. Indeed, bioinformatics analysis suggests that approximately one-third of residues in folded proteins satisfy the geometric requirements to engage in an n→π* interaction, which is likely to be of particular importance for the α-helix. Other carbonyl-dense polymeric materials like polyesters and peptoids are also influenced by n→π* interactions, as are a variety of small molecules, some with particular medicinal importance. Research will continue to identify molecules whose conformation and activity are affected by the n→π* interaction and will clarify their specific contributions to the structures of biomacromolecules.
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Affiliation(s)
- Robert W. Newberry
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Ronald T. Raines
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
- Department
of Biochemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
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Mykhailiuk PK, Kubyshkin V, Bach T, Budisa N. Peptidyl-Prolyl Model Study: How Does the Electronic Effect Influence the Amide Bond Conformation? J Org Chem 2017; 82:8831-8841. [DOI: 10.1021/acs.joc.7b00803] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Pavel K. Mykhailiuk
- Taras Shevchenko National University of Kyiv, Chemistry Department, Volodymyrska 64, 01601 Kyiv, Ukraine
- Enamine Limited, Chervonotkatska 78, 01103 Kyiv, Ukraine
| | - Vladimir Kubyshkin
- Institute
of Chemistry, Technical University of Berlin, Müller-Breslau-Strasse 10, 10623 Berlin, Germany
| | - Thorsten Bach
- Lehrstuhl
für Organische Chemie I, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Nediljko Budisa
- Institute
of Chemistry, Technical University of Berlin, Müller-Breslau-Strasse 10, 10623 Berlin, Germany
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Chernykh AV, Radchenko DS, Chernykh AV, Kondratov IS, Tolmachova NA, Datsenko OP, Kurkunov MA, Zozulya SX, Kheylik YP, Bartels K, Daniliuc CG, Haufe G. Synthesis and Physicochemical Properties of 3-Fluorocyclobutylamines. European J Org Chem 2015. [DOI: 10.1002/ejoc.201500746] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Krow GR, Shoulders MD, Edupuganti R, Gandla D, Yu F, Sonnet PE, Sender M, Choudhary A, DeBrosse C, Ross CW, Carroll P, Raines RT. Synthesis of 5-fluoro- and 5-hydroxymethanoprolines via lithiation of N-BOC-methanopyrrolidines. Constrained Cγ-exo and Cγ-endo Flp and Hyp conformer mimics. J Org Chem 2012; 77:5331-44. [PMID: 22607128 PMCID: PMC3381989 DOI: 10.1021/jo300700a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Proline derivatives with a C(γ)-exo pucker typically display a high amide bond trans/cis (K(T/C)) ratio. This pucker enhances n→π* overlap of the amide oxygen and ester carbonyl carbon, which favors a trans amide bond. If there were no difference in n→π* interaction between the ring puckers, then the correlation between ring pucker and K(T/C) might be broken. To explore this possibility, proline conformations were constrained using a methylene bridge. We synthesized discrete gauche and anti 5-fluoro- and 5-hydroxy-N-acetylmethanoproline methyl esters from 3-syn and 3-anti fluoro- and hydroxymethanopyrrolidines using directed α-metalation to introduce the α-ester group. NBO calculations reveal minimal n→π* orbital interactions, so contributions from other forces might be of greater importance in determining K(T/C) for the methanoprolines. Consistent with this hypothesis, greater trans amide preferences were found in CDCl(3) for anti isomers en-MetFlp and en-MetHyp (72-78% trans) than for the syn stereoisomers ex-MetFlp and ex-MetHyp (54-67% trans). These, and other, K(T/C) results that we report here indicate how substituents on proline analogues can affect amide preferences by pathways other than ring puckering and n→π* overlap and suggest that caution should be exercised in assigning enhanced pyrrolidine C(γ)-exo ring puckering based solely on enhanced trans amide preference.
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Affiliation(s)
- Grant R Krow
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA.
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Recent applications of the (TMS)3SiH radical-based reagent. Molecules 2012; 17:527-55. [PMID: 22269866 PMCID: PMC6268903 DOI: 10.3390/molecules17010527] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 12/29/2011] [Accepted: 01/02/2012] [Indexed: 12/29/2022] Open
Abstract
This review article focuses on the recent applications of tris(trimethylsilyl)silane as a radical-based reagent in organic chemistry. Numerous examples of the successful use of (TMS)(3)SiH in radical reductions, hydrosilylation and consecutive radical reactions are given. The use of (TMS)(3)SiH allows reactions to be carried out under mild conditions with excellent yields of products and remarkable chemo-, regio-, and stereoselectivity. The strategic role of (TMS)(3)SiH in polymerization is underlined with emphasis on the photo-induced radical polymerization of olefins and photo-promoted cationic polymerization of epoxides.
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