1
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Deore B, Kwok RW, Toregeldiyeva M, Vázquez JT, Marianski M, Sanhueza CA. Conformational Properties of Aryl S-Glucosides in Solution. J Org Chem 2023; 88:15569-15579. [PMID: 37933138 PMCID: PMC11078472 DOI: 10.1021/acs.joc.3c01156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023]
Abstract
The conformational study of saccharides and glycomimetics in solution is critical for a comprehensive understanding of their interactions with biological receptors and enabling the design of optimized glycomimetics. Here, we report a nuclear magnetic resonance (NMR) study centered on the conformational properties of the hydroxymethyl group and glycosidic bond of four series of aryl S-glucosides. We found that in acetyl-protected and free aryl S-β-glucosides, the rotational equilibrium around the C5-C6 bond (hydroxymethyl group) exhibits a linear dependence on the electronic properties of the aglycone, namely, as the aryl's substituent electron-withdrawing character increases, the dominance of the gg rotamer declines and the gt contribution rises. Likewise, the conformational equilibrium around the glycosidic C1-S bond also depends on the aglycone's electronic properties, where glucosides carrying electron-poor aglycones exhibit stiffer glycosidic bonds in comparison to their electron-rich counterparts. In the case of the α anomers, the aglycone's effect over the glycosidic bond conformation is like that observed on their β isomers; however, we observe no aglycone's influence over the hydroxymethyl group conformation in the α-glucosides.
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Affiliation(s)
- Bhavesh Deore
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, New York 11439, United States
| | - Ryan W Kwok
- Department of Chemistry, Hunter College, The City University of New York, 695 Park Avenue, New York, New York 10065, United States
- The Ph.D. Program in Chemistry, Graduate Center of the City University of New York, 365 Fifth Avenue, New York, New York 10016, United States
| | - Malika Toregeldiyeva
- The Bronx High School of Science, 75 W 205th Street, Bronx, New York 10468, United States
| | - Jesús T Vázquez
- Instituto Universitario de Bio-Orgánica "Antonio González", Departamento de Química Orgánica, Universidad de La Laguna, Avenida Astrofísico Francisco Sánchez 2, 38206 La Laguna, Spain
| | - Mateusz Marianski
- Department of Chemistry, Hunter College, The City University of New York, 695 Park Avenue, New York, New York 10065, United States
- The Ph.D. Program in Chemistry, Graduate Center of the City University of New York, 365 Fifth Avenue, New York, New York 10016, United States
| | - Carlos A Sanhueza
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, New York 11439, United States
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2
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Ande C, Crich D. Stereodirecting Effect of Esters at the 4-Position of Galacto- and Glucopyranosyl Donors: Effect of 4- C-Methylation on Side-Chain Conformation and Donor Reactivity, and Influence of Concentration and Stoichiometry on Distal Group Participation. J Org Chem 2023; 88:13883-13893. [PMID: 37677151 PMCID: PMC10563135 DOI: 10.1021/acs.joc.3c01496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Indexed: 09/09/2023]
Abstract
When generated in a mass spectrometer bridged bicyclic 1,3-dioxenium ions derived from 4-O-acylgalactopyranosyl, donors can be observed by infrared spectroscopy at cryogenic temperatures, but they are not seen in the solution phase in contrast to the fused bicyclic 1,3-dioxalenium ions of neighboring group participation. The inclusion of a 4-C-methyl group into a 4-O-benzoyl galactopyranosyl donor enables nuclear magnetic resonance observation of the bicyclic ion arising from participation by the distal ester, with the methyl group influence attributed to ester ground state conformation destabilization. We show that a 4-C-methyl group also influences the side-chain conformation, enforcing a gauche,trans conformation in gluco and galactopyranosides. Competition experiments reveal that the 4-C-methyl group has only a minor influence on the rate of reaction of 4-O-benzoyl or 4-O-benzyl-galacto and glucopyranosyl donors and, consequently, that participation by the distal ester does not result in kinetic acceleration (anchimeric assistance). We demonstrate that the stereoselectivity of the 4-O-benzoyl-4-C-methyl galactopyranosyl donor depends on reaction concentration and additive (diphenyl sulfoxide) stoichiometry and hence that participation by the distal ester is a borderline phenomenon in competition with standard glycosylation mechanisms. An analysis of a recent paper affirming participation by a remote pivalate ester is presented with alternative explanations for the observed phenomena.
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Affiliation(s)
- Chennaiah Ande
- Department
of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, Georgia 30602, United States
| | - David Crich
- Department
of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, Georgia 30602, United States
- Department
of Chemistry, University of Georgia, 302 East Campus Road, Athens, Georgia 30602, United States
- Complex
Carbohydrate Research Center, University
of Georgia, 315 Riverbend
Road, Athens, Georgia 30602, United States
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3
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Poškaitė G, Wheatley DE, Wells N, Linclau B, Sinnaeve D. Obtaining Pure 1H NMR Spectra of Individual Pyranose and Furanose Anomers of Reducing Deoxyfluorinated Sugars. J Org Chem 2023; 88:13908-13925. [PMID: 37754916 PMCID: PMC10563139 DOI: 10.1021/acs.joc.3c01503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Indexed: 09/28/2023]
Abstract
Due to tautomeric equilibria, NMR spectra of reducing sugars can be complex with many overlapping resonances. This hampers coupling constant determination, which is required for conformational analysis and configurational assignment of substituents. Given that mixtures of interconverting species are physically inseparable, easy-to-use techniques that enable facile full 1H NMR characterization of sugars are of interest. Here, we show that individual spectra of both pyranoside and furanoside forms of reducing fluorosugars can be obtained using 1D FESTA. We discuss the unique opportunities offered by FESTA over standard sel-TOCSY and show how it allows a more complete characterization. We illustrate the power of FESTA by presenting the first full NMR characterization of many fluorosugars, including of the important fluorosugar 2-deoxy-2-fluoroglucose. We discuss in detail all practical considerations for setting up FESTA experiments for fluorosugars, which can be extended to any mixture of fluorine-containing species interconverting slowly on the NMR frequency-time scale.
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Affiliation(s)
- Gabija Poškaitė
- School
of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - David E. Wheatley
- School
of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - Neil Wells
- School
of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - Bruno Linclau
- School
of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
- Department
of Organic and Macromolecular Chemistry, Ghent University, Campus
Sterre, Krijgslaan 281-S4, Ghent 9000, Belgium
| | - Davy Sinnaeve
- Univ. Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1167 RID-AGE - Risk Factors and Molecular Determinants of Aging-Related Diseases, F-59000 Lille, France
- CNRS, EMR9002 Integrative Structural Biology, F-59000 Lille, France
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4
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Tseng PS, Ande C, Moremen KW, Crich D. Influence of Side Chain Conformation on the Activity of Glycosidase Inhibitors. Angew Chem Int Ed Engl 2023; 62:e202217809. [PMID: 36573850 PMCID: PMC9908843 DOI: 10.1002/anie.202217809] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Indexed: 12/28/2022]
Abstract
Substrate side chain conformation impacts reactivity during glycosylation and glycoside hydrolysis and is restricted by many glycosidases and glycosyltransferases during catalysis. We show that the side chains of gluco and manno iminosugars can be restricted to predominant conformations by strategic installation of a methyl group. Glycosidase inhibition studies reveal that iminosugars with the gauche,gauche side chain conformations are 6- to 10-fold more potent than isosteric compounds with the gauche,trans conformation; a manno-configured iminosugar with the gauche,gauche conformation is a 27-fold better inhibitor than 1-deoxymannojirimycin. The results are discussed in terms of the energetic benefits of preorganization, particularly when in synergy with favorable hydrophobic interactions. The demonstration that inhibitor side chain preorganization can favorably impact glycosidase inhibition paves the way for improved inhibitor design through conformational preorganization.
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Affiliation(s)
- Po-Sen Tseng
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA 30602 (USA),Department of Chemistry, University of Georgia, Athens, GA 30602 (USA),Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602 (USA)
| | - Chennaiah Ande
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA 30602 (USA)
| | - Kelley W. Moremen
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602 (USA),Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602 (USA)
| | - David Crich
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA 30602 (USA),Department of Chemistry, University of Georgia, Athens, GA 30602 (USA),Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602 (USA)
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5
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Arachchige SS, Crich D. Side Chain Conformation and Its Influence on Glycosylation Selectivity in Hexo- and Higher Carbon Furanosides. J Org Chem 2022; 87:316-339. [PMID: 34905382 PMCID: PMC8741747 DOI: 10.1021/acs.joc.1c02374] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
We describe the synthesis and side chain conformational analysis of a series of four 6-deoxy-2,3,5-tri-O-benzyl hexofuranosyl donors with the d-gluco, l-ido, d-altro, and l-galacto configurations. The conformation of the exocyclic bond of these compounds depends on the relative configuration of the point of attachment of the side chain to the ring and of the two flanking centers and can be predicted on that basis analogously to the heptopyranose analogs. Variable-temperature nuclear magnetic resonance (VT NMR) spectroscopy of the activated donors reveals complex, configuration-dependent mixtures of intermediates that we interpret in terms of fused and bridged oxonium ions arising from participation by the various benzyl ethers. The increased importance of ether participation in the furanoside series compared to the pyranosides is discussed in terms of the reduced stabilization afforded to furanosyl oxocarbenium ions by covalent triflate formation. The stereoselectivities of the four donors are discussed on the basis of the benzyl ether participation model.
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Affiliation(s)
- Sameera Siyabalapitiya Arachchige
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, GA 30602, USA,Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA,Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, GA 30602, USA
| | - David Crich
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, GA 30602, USA,Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA,Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, GA 30602, USA
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6
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Weldu WD, Wang CC. Rationalizing the Stereoelectronic Influence of Interglycosidic Bond Conformations on the Reactivity of 1,4- O-Linked Disaccharide Donors. J Org Chem 2021; 86:17906-17917. [PMID: 34818891 DOI: 10.1021/acs.joc.1c02207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Disaccharide donors are key precursors in convergent glycan synthesis strategies. Unexpectedly, we observed that disaccharide thioglycosyl donors containing 1,4-O-linked α-glycosidic bonds are much more reactive than their β-analogues with the same protecting group pattern. Herein, we rationalized that such a difference in their reactivity is attributed to the conformation of the 1,4-O-interglycosidic bond which is controlled by anomeric and exo-anomeric effects. Moreover, the conformational preferences of these donors are dictated by the dihedral angles ϕ and ψ of their interglycosidic linkages and the torsional angle ω of their side chain along the C5-C6 bond. This fundamental research clarifies how the long-range stereoelectronic effects from the nonreducing end sugar can influence the reactivity of the leaving group at the reducing end and the behavior of disaccharide donors thereof.
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Affiliation(s)
- Welday Desta Weldu
- Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan.,Sustainable Chemical Science and Technology (SCST), Taiwan International Graduate Program (TIGP), Academia Sinica, Taipei 115, Taiwan.,Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Cheng-Chung Wang
- Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan.,Sustainable Chemical Science and Technology (SCST), Taiwan International Graduate Program (TIGP), Academia Sinica, Taipei 115, Taiwan
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7
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Ruda A, Widmalm G, Wohlert J. O-Methylation in Carbohydrates: An NMR and MD Simulation Study with Application to Methylcellulose. J Phys Chem B 2021; 125:11967-11979. [PMID: 34704449 PMCID: PMC8573740 DOI: 10.1021/acs.jpcb.1c07293] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
![]()
Methylated carbohydrates
are important from both biological and
technical perspectives. Specifically, methylcellulose is an interesting
cellulose derivative that has applications in foods, materials, cosmetics,
and many other fields. While the molecular dynamics simulation technique
has the potential for both advancing the fundamental understanding
of this polymer and aiding in the development of specific applications,
a general drawback is the lack of experimentally validated interaction
potentials for the methylated moieties. In the present study, simulations
using the GROMOS 56 carbohydrate force field are compared to NMR spin–spin
coupling constants related to the conformation of the exocyclic torsion
angle ω in d-glucopyranose and derivatives containing
a 6-O-methyl substituent and a 13C-isotopologue thereof.
A 3JCC Karplus-type relationship
is proposed for the C5–C6–O6–CMe torsion
angle. Moreover, solvation free energies are compared to experimental
data for small model compounds. Alkylation in the form of 6-O-methylation
affects exocyclic torsion only marginally. Computed solvation free
energies between nonmethylated and methylated molecules were internally
consistent, which validates the application of these interaction potentials
for more specialized purposes.
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Affiliation(s)
- Alessandro Ruda
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Göran Widmalm
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Jakob Wohlert
- Department of Fiber and Polymer Technology, School of Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.,Wallenberg Wood Science Center, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
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8
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Upadhyaya K, Bagul RS, Crich D. Influence of Configuration at the 4- and 6-Positions on the Conformation and Anomeric Reactivity and Selectivity of 7-Deoxyheptopyranosyl Donors: Discovery of a Highly Equatorially Selective l- glycero-d- gluco-Heptopyranosyl Donor. J Org Chem 2021; 86:12199-12225. [PMID: 34343001 DOI: 10.1021/acs.joc.1c01535] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The preparation of four per-O-benzyl-d- or l-glycero-d-galacto and d- or l-glycero-d-gluco heptopyranosyl sulfoxides and the influence of their side-chain conformations on reactivity and stereoselectivity in glycosylation reactions are described. The side-chain conformation in these donors is determined by the relative configuration of its point of attachment to the pyranoside ring and the two flanking centers in agreement with a recent model. In the d- and l-glycero-d-galacto glycosyl donors, the d-glycero-d-galacto isomer with the more electron-withdrawing trans,gauche conformation of its side chain was the more equatorially selective isomer. In the d- and l-glycero-d-gluco glycosyl donors, the l-glycero-d-gluco isomer with the least disarming gauche,gauche side-chain conformation was the most equatorially selective donor. Variable temperature NMR studies, while supporting the formation of intermediate glycosyl triflates at -80 °C in all cases, were inconclusive owing to a change in the decomposition mechanism with the change in configuration. It is suggested that the equatorial selectivity of the l-glycero-d-gluco isomer arises from H-bonding between the glycosyl acceptor and O6 of the donor, which is poised to deliver the acceptor antiperiplanar to the glycosyl triflate, resulting in a high degree of SN2 character in the displacement reaction.
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Affiliation(s)
- Kapil Upadhyaya
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, Georgia 30602, United States
| | - Rahul S Bagul
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, Georgia 30602, United States.,Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia 30602, United States
| | - David Crich
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, Georgia 30602, United States.,Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia 30602, United States.,Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, Georgia 30602, United States
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9
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Wheatley DE, Fontenelle CQ, Kuppala R, Szpera R, Briggs EL, Vendeville JB, Wells NJ, Light ME, Linclau B. Synthesis and Structural Characteristics of all Mono- and Difluorinated 4,6-Dideoxy-d- xylo-hexopyranoses. J Org Chem 2021; 86:7725-7756. [PMID: 34029099 DOI: 10.1021/acs.joc.1c00796] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Protein-carbohydrate interactions are implicated in many biochemical/biological processes that are fundamental to life and to human health. Fluorinated carbohydrate analogues play an important role in the study of these interactions and find application as probes in chemical biology and as drugs/diagnostics in medicine. The availability and/or efficient synthesis of a wide variety of fluorinated carbohydrates is thus of great interest. Here, we report a detailed study on the synthesis of monosaccharides in which the hydroxy groups at their 4- and 6-positions are replaced by all possible mono- and difluorinated motifs. Minimization of protecting group use was a key aim. It was found that introducing electronegative substituents, either as protecting groups or as deoxygenation intermediates, was generally beneficial for increasing deoxyfluorination yields. A detailed structural study of this set of analogues demonstrated that dideoxygenation/fluorination at the 4,6-positions caused very little distortion both in the solid state and in aqueous solution. Unexpected trends in α/β anomeric ratios were identified. Increasing fluorine content always increased the α/β ratio, with very little difference between regio- or stereoisomers, except when 4,6-difluorinated.
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Affiliation(s)
- David E Wheatley
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
| | - Clement Q Fontenelle
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
| | - Ramakrishna Kuppala
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
| | - Robert Szpera
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
| | - Edward L Briggs
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
| | | | - Neil J Wells
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
| | - Mark E Light
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
| | - Bruno Linclau
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
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10
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Tyrikos‐Ergas T, Bordoni V, Fittolani G, Chaube MA, Grafmüller A, Seeberger PH, Delbianco M. Systematic Structural Characterization of Chitooligosaccharides Enabled by Automated Glycan Assembly. Chemistry 2021; 27:2321-2325. [PMID: 33290603 PMCID: PMC7898498 DOI: 10.1002/chem.202005228] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Indexed: 01/01/2023]
Abstract
Chitin, a polymer composed of β(1-4)-linked N-acetyl-glucosamine monomers, and its partially deacetylated analogue chitosan, are abundant biopolymers with outstanding mechanical as well as elastic properties. Their degradation products, chitooligosaccharides (COS), can trigger the innate immune response in humans and plants. Both material and biological properties are dependent on polymer length, acetylation, as well as the pH. Without well-defined samples, a complete molecular description of these factors is still missing. Automated glycan assembly (AGA) enabled rapid access to synthetic well-defined COS. Chitin-cellulose hybrid oligomers were prepared as important tools for a systematic structural analysis. Intramolecular interactions, identified by molecular dynamics simulations and NMR analysis, underscore the importance of the chitosan amino group for the stabilization of specific geometries.
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Affiliation(s)
- Theodore Tyrikos‐Ergas
- Department of Biomolecular SystemsMax-Planck-Institute of Colloids and InterfacesAm Mühlenberg 114476PotsdamGermany
- Department of Chemistry and BiochemistryFreie Universität BerlinArnimallee 2214195BerlinGermany
| | - Vittorio Bordoni
- Department of Biomolecular SystemsMax-Planck-Institute of Colloids and InterfacesAm Mühlenberg 114476PotsdamGermany
| | - Giulio Fittolani
- Department of Biomolecular SystemsMax-Planck-Institute of Colloids and InterfacesAm Mühlenberg 114476PotsdamGermany
- Department of Chemistry and BiochemistryFreie Universität BerlinArnimallee 2214195BerlinGermany
| | - Manishkumar A. Chaube
- Department of Biomolecular SystemsMax-Planck-Institute of Colloids and InterfacesAm Mühlenberg 114476PotsdamGermany
| | - Andrea Grafmüller
- Department of TheoryMax-Planck-Institute of Colloids and InterfacesAm Mühlenberg 114476PotsdamGermany
| | - Peter H. Seeberger
- Department of Biomolecular SystemsMax-Planck-Institute of Colloids and InterfacesAm Mühlenberg 114476PotsdamGermany
- Department of Chemistry and BiochemistryFreie Universität BerlinArnimallee 2214195BerlinGermany
| | - Martina Delbianco
- Department of Biomolecular SystemsMax-Planck-Institute of Colloids and InterfacesAm Mühlenberg 114476PotsdamGermany
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11
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Rajasekaran P, Pirrone MG, Crich D. Influence of substitution at the 5α-Position on the side chain conformation of glucopyranosides. Carbohydr Res 2021; 500:108254. [PMID: 33561715 DOI: 10.1016/j.carres.2021.108254] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 10/22/2022]
Abstract
We describe the preparation of methyl 5α-methyl-α-d-glucopyranoside and of 5α-fluoro-β-d-glucopyranose per acetate and the NMR-based conformational analysis of their side chains. Both the 5α-methyl and 5α-fluoro substituents increase the population of the gauche,gauche side chain conformer to the extent that it becomes the predominant conformation. In the 5α-methyl series this is attributed to steric effects, whereas in the 5α-fluoro series the optimization of attractive gauche effects is the more likely reason.
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Affiliation(s)
- Parasuraman Rajasekaran
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, GA, 30602, USA; Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA
| | - Michael G Pirrone
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, GA, 30602, USA; Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA
| | - David Crich
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, GA, 30602, USA; Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA; Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, GA, 30602, USA.
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12
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Pirrone MG, Gysin M, Haldimann K, Hobbie SN, Vasella A, Crich D. Predictive Analysis of the Side Chain Conformation of the Higher Carbon Sugars: Application to the Preorganization of the Aminoglycoside Ring 1 Side Chain for Binding to the Bacterial Ribosomal Decoding A Site. J Org Chem 2020; 85:16043-16059. [PMID: 32902280 PMCID: PMC7749010 DOI: 10.1021/acs.joc.0c01836] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
With a view to facilitating prediction of the exocyclic bond to the pyranoside ring in higher carbon sugars, a model is advanced that relates the relative configuration of the three stereogenic centers comprised of the branchpoint and of the two flanking centers (C4-C5-C6 in aldoheptoses and higher and C5-C6-C7 in sialic and ulosonic acids) to that of the simple ring-opened pentoses. Assignment of a given stereotriad as arabino, lxyo, ribo, or xylo by inspection of the Fischer projection formulas permits prediction of conformation of the exocyclic bond by comparison with the known solution (= crystal in all cases) conformations of the simple pentitols. More remote stereogenic centers in the side chain, as in the 8-position of N-acetylneuraminic acid, have little impact on the conformation of the exocyclic bond. On the basis of this model the conformation of the exocyclic bond in ring I of 6'-homologated 4,5-disubstituted 2-deoxystreptamine class aminoglycoside antibiotics was predicted and was borne out by NMR analysis of newly synthesized derivatives in D2O at pD5. The antiribosomal and antibacterial activity of these derivatives is briefly presented and discussed in terms of preorganization of the side chain for binding to the ribosomal decoding A site. It is anticipated that this predictive analysis will also find use in the prediction of the conformation of the exocyclic bonds in other 2-(1-hydroxyalkyl)-3-hydroxytetrahydropyrans and tetrahydrofurans.
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Affiliation(s)
- Michael G Pirrone
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, Georgia 30602, United States
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia 30602, United States
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Marina Gysin
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 28, 8006 Zürich, Switzerland
| | - Klara Haldimann
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 28, 8006 Zürich, Switzerland
| | - Sven N Hobbie
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 28, 8006 Zürich, Switzerland
| | - Andrea Vasella
- Organic Chemistry Laboratory, ETH Zürich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland
| | - David Crich
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, Georgia 30602, United States
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia 30602, United States
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
- Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, Georgia 30602, United States
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13
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Quirke JCK, Crich D. Glycoside Hydrolases Restrict the Side Chain Conformation of Their Substrates To Gain Additional Transition State Stabilization. J Am Chem Soc 2020; 142:16965-16973. [PMID: 32877175 PMCID: PMC7544649 DOI: 10.1021/jacs.0c05592] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Carbohydrate side chain conformation confers a significant influence on reactivity during glycosylation and anomeric bond hydrolysis due to stabilization of the oxocarbenium-like transition state. By analysis of 513 pyranoside-bound glycoside hydrolase (GH) crystal structures, we determine that most glucosidases and β-mannosidases preferentially bind their substrates in the most reactive gauche,gauche (gg) conformation, thereby maximizing stabilization of the corresponding oxocarbenium ion-like transition state during hydrolysis. α-Galactoside hydrolases mostly show a preference for the second most activating gauche,trans (gt) conformation to avoid the energy penalty that would arise from imposing the gg conformation on galacto-configured ligands. These preferences stand in stark contrast to the side chain populations observed for these sugars both in free solution and bound to nonhydrolytic proteins, where for the most part a much greater diversity of side chain conformations is observed. Analysis of sequences of GH-ligand complexes reveals that side chain restriction begins with the enzyme-substrate complex and persists through the transition state until release of the hydrolysis product, despite changes in ring conformation along the reaction coordinate. This work will inform the design of new generations of glycosidase inhibitors with restricted side chains that confer higher selectivity and/or affinity.
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Affiliation(s)
- Jonathan C K Quirke
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, Georgia 30602, United States
- Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, Georgia 30602, United States
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia 30602, United States
| | - David Crich
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, Georgia 30602, United States
- Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, Georgia 30602, United States
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia 30602, United States
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14
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Pirrone MG, Matsushita T, Vasella A, Crich D. Stereospecific synthesis of methyl 2-amino-2,4-dideoxy-6S-deuterio-α-D-xylo-hexopyranoside and methyl 2-amino-2,4-dideoxy-6S-deuterio-4-propyl-α-d-glucopyranoside: Side chain conformation of the novel aminoglycoside antibiotic propylamycin. Carbohydr Res 2020; 491:107984. [PMID: 32217361 DOI: 10.1016/j.carres.2020.107984] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/11/2020] [Accepted: 03/12/2020] [Indexed: 12/20/2022]
Abstract
The stereospecific syntheses of methyl 2-amino-2,4-dideoxy-4-C-propyl-α-d-glucopyranoside and of methyl 2-amino-2,4-dideoxy-α-D-xylo-hexopyranoside and of their 6S-deuterioisotopomers are described as models for ring I of the aminoglycoside antibiotics propylamycin and 4'-deoxyparomomycin, respectively. Analysis of the 1H NMR spectra of these compounds and of methyl 2-amino-2-deoxy-α-d-glucopyranoside, a model for paromomycin itself, reveals that neither deoxygenation at the 4-position, nor substitution of the C-O bond at the 4-postion by a C-C bond significantly changes the distribution of the side chain population between the three possible staggered conformations. From this it is concluded that the beneficial effect on antiribosomal and antibacterial activity of the propyl group in propylamycin does not derive from a change in side chain conformation. Rather, enhanced basicity of the ring oxygen and increased hydrophobicity and/or solvation effects are implicated.
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Affiliation(s)
- Michael G Pirrone
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, GA, 30602, USA; Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, GA, 30602, USA; Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA; Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI, 48202, USA
| | - Takahiko Matsushita
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI, 48202, USA
| | - Andrea Vasella
- Organic Chemistry Laboratory, ETH Zürich, Vladimir-Prelog-Weg 1-5/10, 8093, Zürich, Switzerland
| | - David Crich
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, 250 West Green Street, Athens, GA, 30602, USA; Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, GA, 30602, USA; Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA; Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI, 48202, USA.
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15
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Abstract
We describe the synthesis of the unusual bicyclic sugar bradyrhizose in 14 steps and a 6% overall yield from d-glucose. The synthesis involves the elaboration of a trans-fused carbocyclic ring onto the preexisting glucopyranose framework followed by adjustment of the oxidation levels. Key steps include radical extension of the glucopyranose side chain, ring closing metathesis, allylic oxidation, Luche reduction, hydroxy-directed epoxidation, and acid-catalyzed epoxide opening at the more substituted position.
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Affiliation(s)
- Philemon Ngoje
- Department of Pharmaceutical and Biomedical Sciences , University of Georgia , 250 West Green Street , Athens , Georgia 30602 , United States.,Department of Chemistry , Wayne State University , 5101 Cass Avenue , Detroit , Michigan 48202 , United States
| | - David Crich
- Department of Pharmaceutical and Biomedical Sciences , University of Georgia , 250 West Green Street , Athens , Georgia 30602 , United States.,Department of Chemistry , Wayne State University , 5101 Cass Avenue , Detroit , Michigan 48202 , United States.,Department of Chemistry , University of Georgia , 140 Cedar Street , Athens , Georgia 30602 , United States.,Complex Carbohydrate Research Center , University of Georgia , 315 Riverbend Road , Athens , Georgia 30602 , United States
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16
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Colombo C, Bennet AJ. The physical organic chemistry of glycopyranosyl transfer reactions in solution and enzyme-catalyzed. Curr Opin Chem Biol 2019; 53:145-157. [PMID: 31689605 DOI: 10.1016/j.cbpa.2019.08.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 08/03/2019] [Accepted: 08/10/2019] [Indexed: 12/14/2022]
Abstract
Our understanding of the mechanisms of glycopyranosyl transfer that occur in solution, both for the chemical synthesis of complex structures and that for the cleavage of glycosidic bonds has allowed us to design biologically active molecules. Recent efforts on the reactivity of glycopyranosides, which are critical entities in all biological systems, coupled with the advent of modern spectroscopic instrumentation have allowed physical organic chemists to broaden our knowledge of glycosyl transfer reaction transition states, both in solution and for enzyme-catalyzed processes, and of critical high energy intermediates. This review details recent physical organic, kinetic and structural studies that have led to elucidation of several different mechanism for the transfer of glycopyranosyl moieties from various substrates to acceptors, such as water or a sugar hydroxyl group.
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17
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Simard RD, Joyal M, Gillard L, Di Censo G, Maharsy W, Beauregard J, Colarusso P, Patel KD, Prévost M, Nemer M, Guindon Y. Synthesis of Sialyl Lewis X Glycomimetics Bearing a Bicyclic 3- O,4- C-Fused Galactopyranoside Scaffold. J Org Chem 2019; 84:7372-7387. [PMID: 31088084 DOI: 10.1021/acs.joc.9b01075] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Reported herein is the synthesis of sialyl LewisX analogues bearing a trans-bicyclo[4.4.0] dioxadecane-modified 3- O,4- C-fused galactopyranoside scaffold that locks the carboxylate pharmacophore in either the axial or equatorial position. This novel series of bicyclic galactopyranosides are prepared through a stereocontrolled intramolecular cyclization reaction that has been evaluated both experimentally and by density functional theory calculations. The cyclization precursors are obtained from β-d-galactose pentaacetate in a nine-step sequence featuring a highly diastereoselective equatorial alkynylation and Cu(I) catalyzed formation of the acetylenic α-ketoester moiety. Preliminary biological evaluations indicate improved activity as P-selectin antagonists for the axially configured analogues as compared to their equatorial counterparts.
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Affiliation(s)
- Ryan D Simard
- Bio-Organic Chemistry Laboratory , Institut de Recherches Cliniques de Montréal , Montréal , Québec H2W 1R7 , Canada.,Department of Chemistry , Université de Montréal , Montréal , Québec H3C 3J7 , Canada
| | - Mathieu Joyal
- Department of Biochemistry, Microbiology and Immunology , University of Ottawa , Ottawa , Ontario K1N 6N5 , Canada
| | - Laura Gillard
- Bio-Organic Chemistry Laboratory , Institut de Recherches Cliniques de Montréal , Montréal , Québec H2W 1R7 , Canada
| | - Gianna Di Censo
- Bio-Organic Chemistry Laboratory , Institut de Recherches Cliniques de Montréal , Montréal , Québec H2W 1R7 , Canada
| | - Wael Maharsy
- Department of Biochemistry, Microbiology and Immunology , University of Ottawa , Ottawa , Ontario K1N 6N5 , Canada
| | - Janie Beauregard
- Department of Biochemistry, Microbiology and Immunology , University of Ottawa , Ottawa , Ontario K1N 6N5 , Canada
| | - Pina Colarusso
- Live Cell Imaging Laboratory, Snyder Institute for Chronic Diseases , University of Calgary , Calgary , Alberta T2N 4N1 , Canada
| | - Kamala D Patel
- Live Cell Imaging Laboratory, Snyder Institute for Chronic Diseases , University of Calgary , Calgary , Alberta T2N 4N1 , Canada
| | - Michel Prévost
- Bio-Organic Chemistry Laboratory , Institut de Recherches Cliniques de Montréal , Montréal , Québec H2W 1R7 , Canada
| | - Mona Nemer
- Department of Biochemistry, Microbiology and Immunology , University of Ottawa , Ottawa , Ontario K1N 6N5 , Canada
| | - Yvan Guindon
- Bio-Organic Chemistry Laboratory , Institut de Recherches Cliniques de Montréal , Montréal , Québec H2W 1R7 , Canada.,Department of Chemistry , Université de Montréal , Montréal , Québec H3C 3J7 , Canada.,Department of Biochemistry, Microbiology and Immunology , University of Ottawa , Ottawa , Ontario K1N 6N5 , Canada
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18
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Malassis J, Vendeville JB, Nguyen QH, Boujon M, Gaignard-Gaillard Q, Light M, Linclau B. Synthesis of vicinal dideoxy-difluorinated galactoses. Org Biomol Chem 2019; 17:5331-5340. [DOI: 10.1039/c9ob00707e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three novel dideoxydifluorinated galactose derivatives are described.
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Affiliation(s)
- Julien Malassis
- School of Chemistry
- University of Southampton
- Southampton SO171BJ
- UK
| | | | - Qui-Hien Nguyen
- School of Chemistry
- University of Southampton
- Southampton SO171BJ
- UK
| | - Marie Boujon
- School of Chemistry
- University of Southampton
- Southampton SO171BJ
- UK
| | | | - Mark Light
- School of Chemistry
- University of Southampton
- Southampton SO171BJ
- UK
| | - Bruno Linclau
- School of Chemistry
- University of Southampton
- Southampton SO171BJ
- UK
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19
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Dharuman S, Amarasekara H, Crich D. Interplay of Protecting Groups and Side Chain Conformation in Glycopyranosides. Modulation of the Influence of Remote Substituents on Glycosylation? J Org Chem 2018; 83:10334-10351. [PMID: 30063354 PMCID: PMC6131524 DOI: 10.1021/acs.joc.8b01459] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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The synthesis and
conformational analysis of a series of phenyl
2,3,6-tri-O-benzyl-β-d-thio galacto-
and glucopyranosides and their 6S-deuterio isotopomers,
with systematic variation of the protecting group at the 4-position,
are described. For the galactopyranosides, replacement of a 4-O-benzyl ether by a 4-O-alkanoyl or aroyl
ester results in a small but measurable shift in side chain population
away from the trans,gauche conformation
and in favor of the gauche,trans conformer. In the glucopyranoside series on the other hand, replacement
of a 4-O-benzyl ether by a 4-O-alkanoyl
or aroyl ester results in a small but measurable increase in the population
of the trans,gauche conformer at
the expense of the gauche,gauche conformer. The possible modulating effect of these conformational
changes on the well-known changes in the anomeric reactivity of glycosyl
donors as a function of protecting group is discussed, raising the
possibility that larger changes may be observed at the transition
state for glycosylation. A comparable study with a series of ethyl
2,3,4-tri-O-benzyl-β-d-thioglucopyranosides
reveals that no significant influence in side chain population is
observed on changing the O6 protecting group.
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Affiliation(s)
- Suresh Dharuman
- Department of Chemistry , Wayne State University , 5101 Cass Avenue , Detroit , Michigan 48202 , United States
| | - Harsha Amarasekara
- Department of Chemistry , Wayne State University , 5101 Cass Avenue , Detroit , Michigan 48202 , United States
| | - David Crich
- Department of Chemistry , Wayne State University , 5101 Cass Avenue , Detroit , Michigan 48202 , United States
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