1
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Ganguly HK, Ludwig BA, Tressler CM, Bhatt MR, Pandey AK, Quinn CM, Bai S, Yap GPA, Zondlo NJ. 4,4-Difluoroproline as a Unique 19F NMR Probe of Proline Conformation. Biochemistry 2024; 63:1131-1146. [PMID: 38598681 DOI: 10.1021/acs.biochem.3c00697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
Despite the importance of proline conformational equilibria (trans versus cis amide and exo versus endo ring pucker) on protein structure and function, there is a lack of convenient ways to probe proline conformation. 4,4-Difluoroproline (Dfp) was identified to be a sensitive 19F NMR-based probe of proline conformational biases and cis-trans isomerism. Within model compounds and disordered peptides, the diastereotopic fluorines of Dfp exhibit similar chemical shifts (ΔδFF = 0-3 ppm) when a trans X-Dfp amide bond is present. In contrast, the diastereotopic fluorines exhibit a large (ΔδFF = 5-12 ppm) difference in chemical shift in a cis X-Dfp prolyl amide bond. DFT calculations, X-ray crystallography, and solid-state NMR spectroscopy indicated that ΔδFF directly reports on the relative preference of one proline ring pucker over the other: a fluorine which is pseudo-axial (i.e., the pro-4R-F in an exo ring pucker, or the pro-4S-F in an endo ring pucker) is downfield, while a fluorine which is pseudo-equatorial (i.e., pro-4S-F when exo, or pro-4R-F when endo) is upfield. Thus, when a proline is disordered (a mixture of exo and endo ring puckers, as at trans-Pro in peptides in water), it exhibits a small Δδ. In contrast, when the Pro is ordered (i.e., when one ring pucker is strongly preferred, as in cis-Pro amide bonds, where the endo ring pucker is strongly favored), a large Δδ is observed. Dfp can be used to identify inherent induced order in peptides and to quantify proline cis-trans isomerism. Using Dfp, we discovered that the stable polyproline II helix (PPII) formed in the denatured state (8 M urea) exhibits essentially equal populations of the exo and endo proline ring puckers. In addition, the data with Dfp suggested the specific stabilization of PPII by water over other polar solvents. These data strongly support the importance of carbonyl solvation and n → π* interactions for the stabilization of PPII. Dfp was also employed to quantify proline cis-trans isomerism as a function of phosphorylation and the R406W mutation in peptides derived from the intrinsically disordered protein tau. Dfp is minimally sterically disruptive and can be incorporated in expressed proteins, suggesting its broad application in understanding proline cis-trans isomerization, protein folding, and local order in intrinsically disordered proteins.
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Affiliation(s)
- Himal K Ganguly
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Brice A Ludwig
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Caitlin M Tressler
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Megh R Bhatt
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Anil K Pandey
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Caitlin M Quinn
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Shi Bai
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Glenn P A Yap
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Neal J Zondlo
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
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2
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Zhou M, Ren JX, Feng XT, Zhao HY, Fu XP, Min QQ, Zhang X. Late-stage gem-difluoroallylation of phenol in bioactive molecules and peptides with 3,3-difluoroallyl sulfonium salts. Chem Sci 2024; 15:2937-2945. [PMID: 38404383 PMCID: PMC10882445 DOI: 10.1039/d3sc06302j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 01/13/2024] [Indexed: 02/27/2024] Open
Abstract
An efficient method for the late-stage selective O-fluoroalkylation of tyrosine residues with a stable yet highly reactive fluoroalkylating reagent, 3,3-difluoroallyl sulfonium salts (DFASs), has been developed. The reaction proceeds in a mild basic aqueous buffer (pH = 11.6) with high efficiency, high biocompatibility, and excellent regio- and chemoselectivity. Various oligopeptides and phenol-containing bioactive molecules, including carbohydrates and nucleosides, could be selectively O-fluoroalkylated. The added vinyl and other functional groups from DFASs can be valuable linkers for successive modification, significantly expanding the chemical space for further bioconjugation. The synthetic utility of this protocol has been demonstrated by the fluorescently labeled anti-cancer drug and the synthesis of O-link type 1,4,7,10-tetraazacyclododecane-N,N',N,N'-tetraacetic acid-tyrosine3-octreotate (DOTA-TATE), showing the prospect of the method in medicinal chemistry and chemical biology.
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Affiliation(s)
- Minqi Zhou
- College of Chemistry and Henan Institute of Advanced Technology, Zhengzhou University Zhengzhou 450001 China
| | - Jin-Xiu Ren
- Key Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials (Chinese Academy of Sciences), Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Xiao-Tian Feng
- College of Chemistry and Henan Institute of Advanced Technology, Zhengzhou University Zhengzhou 450001 China
| | - Hai-Yang Zhao
- Key Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials (Chinese Academy of Sciences), Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Xia-Ping Fu
- Key Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials (Chinese Academy of Sciences), Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Qiao-Qiao Min
- Key Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials (Chinese Academy of Sciences), Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Xingang Zhang
- College of Chemistry and Henan Institute of Advanced Technology, Zhengzhou University Zhengzhou 450001 China
- Key Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials (Chinese Academy of Sciences), Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
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3
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Wu H, Li Y, Sun M, Zhang J, Li J, Yang J. Highly Diastereoselective [3 + 2] Cycloaddition of Aziridines with Difluorinated Silyl Enol Ethers: Divergent Synthesis of 4,4-Difluoropyrrolidines and 4-Fluoropyrroles. Org Lett 2024; 26:751-756. [PMID: 38214536 DOI: 10.1021/acs.orglett.3c04251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2024]
Abstract
A highly diastereoselective [3 + 2] cycloaddition of aziridines with difluorinated silyl enol ethers has been developed. This approach provides a facile methodology for highly functionalized gem-difluorinated pyrrolidines in good to excellent yields with good functional group tolerance. A one-pot, two-step approach for synthesis of structurally interesting fluorinated pyrroles has also been developed through a cycloaddition/aromatization/desulfonation sequence. Moreover, readily available substrates, mild reaction conditions, and easy scale-up synthesis show practical advantages.
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Affiliation(s)
- Haijian Wu
- Advanced Research Institute and School of Pharmaceutical Science, Taizhou University, Jiaojiang, Zhejiang 318000, People's Republic of China
| | - Yanan Li
- Advanced Research Institute and School of Pharmaceutical Science, Taizhou University, Jiaojiang, Zhejiang 318000, People's Republic of China
| | - Manman Sun
- Advanced Research Institute and School of Pharmaceutical Science, Taizhou University, Jiaojiang, Zhejiang 318000, People's Republic of China
| | - Jing Zhang
- Advanced Research Institute and School of Pharmaceutical Science, Taizhou University, Jiaojiang, Zhejiang 318000, People's Republic of China
| | - Jinshan Li
- Advanced Research Institute and School of Pharmaceutical Science, Taizhou University, Jiaojiang, Zhejiang 318000, People's Republic of China
| | - Jianguo Yang
- Advanced Research Institute and School of Pharmaceutical Science, Taizhou University, Jiaojiang, Zhejiang 318000, People's Republic of China
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4
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Miles SA, Nillama JA, Hunter L. Tinker, Tailor, Soldier, Spy: The Diverse Roles That Fluorine Can Play within Amino Acid Side Chains. Molecules 2023; 28:6192. [PMID: 37687021 PMCID: PMC10489206 DOI: 10.3390/molecules28176192] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 08/17/2023] [Accepted: 08/17/2023] [Indexed: 09/10/2023] Open
Abstract
Side chain-fluorinated amino acids are useful tools in medicinal chemistry and protein science. In this review, we outline some general strategies for incorporating fluorine atom(s) into amino acid side chains and for elaborating such building blocks into more complex fluorinated peptides and proteins. We then describe the diverse benefits that fluorine can offer when located within amino acid side chains, including enabling 19F NMR and 18F PET imaging applications, enhancing pharmacokinetic properties, controlling molecular conformation, and optimizing target-binding.
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Affiliation(s)
| | | | - Luke Hunter
- School of Chemistry, The University of New South Wales (UNSW), Sydney 2052, Australia
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Pavlović RZ, Kop TJ, Nešić M, Stepanović O, Wang X, Todorović N, Rodić MV, Šmit BM. On the Selectivity in the Synthesis of 3-Fluoropiperidines Using BF 3-Activated Hypervalent Iodine Reagents. J Org Chem 2023. [PMID: 37449517 DOI: 10.1021/acs.joc.3c00944] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
Fluorinated piperidines find wide applications, most notably in the development of novel therapies and agrochemicals. Cyclization of alkenyl N-tosylamides promoted by BF3-activated aryliodine(III) carboxylates is an attractive strategy to construct 3-fluoropiperidines, but it suffers from selectivity issues arising from competitive oxoaminations and the inability to easily modulate the reactions diastereoselectivity. Herein, we report an itemized optimization of the reaction conditions carried out on both cyclic and acyclic substrates and outline the origins of substrate- and reagent-based stereo-, regio-, and chemoselectivity. Extensive mechanistic studies encompassing multinuclear NMR spectroscopy, deuterium labeling, rearrangements on stereodefined substrates, and careful structural analyses (NMR and X-ray) of the reaction products are performed. This revealed the processes and interactions crucial for achieving controlled preparation of 3-fluoropiperidines using I(III) chemistry and has provided an advanced understanding of the reaction mechanism. In brief, we propose that BF3-coordinated I(III) reagents attack C═C to produce the corresponding iodiranium(III) ion, which then undergoes diastereodetermining 5-exo-cyclization. Transiently formed pyrrolidines with an exocyclic σ-alkyl-I(III) moiety can further undergo aziridinium ion formation or reductive ligand coupling processes, which dictate not only the final product's ring size but also the chemoselectivity. Importantly, the selectivity of the reaction depends on the nature of the ligand bound to I(III) and the presence of electrolytes such as TBABF4. Reported findings will facilitate the usage of ArI(III)-dicarboxylates in the reliable construction of fluorinated azaheterocycles.
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Affiliation(s)
- Radoslav Z Pavlović
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
- Institute of Chemistry, Technology and Metallurgy, Department of Chemistry, University of Belgrade, Njegoševa 12, Belgrade 11000, Serbia
| | - Tatjana J Kop
- Institute of Chemistry, Technology and Metallurgy, Department of Chemistry, University of Belgrade, Njegoševa 12, Belgrade 11000, Serbia
| | - Marko Nešić
- Roger Adams Laboratory, Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Olivera Stepanović
- Laboratory of Organic Chemistry, ETH Zürich, Vladimir-Prelog-Weg 3, Zürich 8093, Switzerland
| | - Xiuze Wang
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Nina Todorović
- Institute of Chemistry, Technology and Metallurgy, Department of Chemistry, University of Belgrade, Njegoševa 12, Belgrade 11000, Serbia
| | - Marko V Rodić
- Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovića 3, Novi Sad 21000, Serbia
| | - Biljana M Šmit
- Institute for Information Technologies, Department of Science, University of Kragujevac, Jovana Cvijića bb, Kragujevac 34000, Serbia
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Chernykh AV, Aloshyn D, Kuchkovska YO, Daniliuc CG, Tolmachova NA, Kondratov IS, Zozulya S, Grygorenko OO, Haufe G. Impact of β-perfluoroalkyl substitution of proline on the proteolytic stability of its peptide derivatives. Org Biomol Chem 2022; 20:9337-9350. [PMID: 36107003 DOI: 10.1039/d2ob01430k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
A series of all stereoisomers of β-CF3 or β-C2F5 substituted prolines and their dipeptide derivatives were synthesized. Mouse plasma stability assay was carried out to study the impact of fluoroalkyl substituents on the proteolytic stability of proline-derived peptides. The effect of the (R)-/(S)-configuration at the C-2 atom in combination with electronic and steric effects imposed by fluoroalkyl groups was addressed to rationalize the difference in the half-life stability of diastereomeric β-CF3-Pro-Gly and β-C2F5-Pro-Gly derivatives and compared to those of parent (S)-Pro-Gly and (R)-Pro-Gly dipeptides. The steric effect was predominant when the β-CF3 or β-C2F5 group was placed properly to create a spatial interference within the pockets of proteases, thereby protecting the substances from degradation (e.g., for cis-isomeric derivatives). Otherwise, a smaller electronic effect accelerating proteolysis was in charge (i.e., for the (2S,3S) isomers).
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Affiliation(s)
- Anton V Chernykh
- Enamine Ltd., Chervonotkatska Street 78, Kyïv 02094, Ukraine. .,Taras Shevchenko National University of Kyïv, Volodymyrska Street 60, Kyïv 01601, Ukraine.
| | - Danylo Aloshyn
- Bienta/Enamine Ltd., Chervonotkatska Street 78, Kyïv 02094, Ukraine
| | | | - Constantin G Daniliuc
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149 Münster, Germany
| | | | - Ivan S Kondratov
- Enamine Ltd., Chervonotkatska Street 78, Kyïv 02094, Ukraine. .,V.P. Kukhar Institute of Bioorganic Chemistry & Petrochemistry, National Academy of Sciences of, Ukraine, Murmanska Street 1, Kyïv 02660, Ukraine
| | - Sergey Zozulya
- Bienta/Enamine Ltd., Chervonotkatska Street 78, Kyïv 02094, Ukraine
| | - Oleksandr O Grygorenko
- Enamine Ltd., Chervonotkatska Street 78, Kyïv 02094, Ukraine. .,Taras Shevchenko National University of Kyïv, Volodymyrska Street 60, Kyïv 01601, Ukraine.
| | - Günter Haufe
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149 Münster, Germany.,Cells-in-Motion Cluster of Excellence, Universität Münster, Waldeyerstraße 15, 48149 Münster, Germany
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7
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Synthesis of Functionalized Azepines via Cu(I)-Catalyzed Tandem Amination/Cyclization Reaction of Fluorinated Allenynes. Molecules 2022; 27:molecules27165195. [PMID: 36014436 PMCID: PMC9416787 DOI: 10.3390/molecules27165195] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/11/2022] [Accepted: 08/12/2022] [Indexed: 01/17/2023] Open
Abstract
An efficient method for the selective preparation of trifluoromethyl-substituted azepin-2-carboxylates and their phosphorous analogues has been developed via Cu(I)-catalyzed tandem amination/cyclization reaction of functionalized allenynes with primary and secondary amines.
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8
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Cristóbal C, Gaviña D, Alonso I, Ribagorda M, Carretero JC, Del Pozo C, Adrio J. Catalytic enantioselective intramolecular 1,3-dipolar cycloaddition of azomethine ylides with fluorinated dipolarophiles. Chem Commun (Camb) 2022; 58:7805-7808. [PMID: 35735739 DOI: 10.1039/d2cc02902b] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An enantioselective synthesis of polycyclic fluorinated pyrrolidines has been achieved by Cu-catalyzed intramolecular 1,3-dipolar cycloaddition of azomethine ylides with fluorinated dipolarophiles. The method displays a wide scope and afforded the desired cycloadducts in high yields with up to 99% ee. These results demonstrate that fluoroalkyl substituents are excellent activating groups in this transformation.
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Affiliation(s)
- Christian Cristóbal
- Departamento de Química Orgánica, Facultad de Ciencias, C/Francisco Tomás y Valiente 7, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
| | - Daniel Gaviña
- Departamento de Química Orgánica, Universidad de Valencia, E-46100 Burjassot, Spain.
| | - Inés Alonso
- Departamento de Química Orgánica, Facultad de Ciencias, C/Francisco Tomás y Valiente 7, Universidad Autónoma de Madrid, 28049 Madrid, Spain. .,Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid, Spain.,Centro de Innovación en Química Avanzada (ORFEO-CINQA), Spain
| | - María Ribagorda
- Departamento de Química Orgánica, Facultad de Ciencias, C/Francisco Tomás y Valiente 7, Universidad Autónoma de Madrid, 28049 Madrid, Spain. .,Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Juan C Carretero
- Departamento de Química Orgánica, Facultad de Ciencias, C/Francisco Tomás y Valiente 7, Universidad Autónoma de Madrid, 28049 Madrid, Spain. .,Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid, Spain.,Centro de Innovación en Química Avanzada (ORFEO-CINQA), Spain
| | - Carlos Del Pozo
- Departamento de Química Orgánica, Universidad de Valencia, E-46100 Burjassot, Spain.
| | - Javier Adrio
- Departamento de Química Orgánica, Facultad de Ciencias, C/Francisco Tomás y Valiente 7, Universidad Autónoma de Madrid, 28049 Madrid, Spain. .,Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid, Spain.,Centro de Innovación en Química Avanzada (ORFEO-CINQA), Spain
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