1
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Upadhyaya K, Osorio-Morales N, Crich D. Can Side-Chain Conformation and Glycosylation Selectivity of Hexopyranosyl Donors Be Controlled with a Dummy Ligand? J Org Chem 2023; 88:3678-3696. [PMID: 36877600 PMCID: PMC10028612 DOI: 10.1021/acs.joc.2c02889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
The use of a phenylthio group (SPh) as a dummy ligand at the 6-position to control the side-chain conformation of a series of hexopyranosyl donors is described. The SPh group limits side-chain conformation in a configuration-specific manner, which parallels that seen in the heptopyranosides, and so influences glycosylation selectivity. With both d- and l-glycero-d-galacto-configured donors, the equatorial products are highly favored as they are with an l-glycero-d-gluco donor. For the d-glycero-d-gluco donor, on the other hand, modest axial selectivity is observed. Selectivity patterns are discussed in terms of the side-chain conformation of the donors in combination with the electron-withdrawing effect of the thioacetal group. After glycosylation, removal of the thiophenyl moiety and hydrogenolytic deprotection is achieved in a single step with Raney nickel.
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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
| | - Nicolas Osorio-Morales
- 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
| | - 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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2
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Panova MV, Medvedev MG, Orlova AV, Kononov LO. Exhaustive Conformational Search for Sialyl Cation Reveals Possibility of Remote Participation of Acyl Groups. Chemphyschem 2021; 23:e202100788. [PMID: 34837303 DOI: 10.1002/cphc.202100788] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 11/26/2021] [Indexed: 11/11/2022]
Abstract
Finding convenient ways for the stereoselective α-sialylation is important due to the high practical significance of α-sialic acid-containing glycans and neoglycoconjugates. It was proposed that sialylation stereoselectivity is determined by the structure of the sialyl cation (also known in biochemistry as "sialosyl cation"), a supposed intermediate in this reaction. Here we design a new approach for studying the conformational space of highly flexible sialyl cation and find 1625 unique conformers including those stabilized by covalent remote participation (also known as long-range participation) of 4-O-acetyl (4-OAc), 5-N-trifluoroacetyl (5-NTFA), as well as 7,8,9-OAc from both α and β sides. The most energetically stable sialyl cation conformers are featured by 4-OAc participation, closely followed by 5-NTFA- and 7-OAc-stabilized conformers; unstabilized sialyl cation conformers are ∼10 kcal mol-1 less stable than the 4-OAc-stabilized ones. Analysis of all the obtained conformers by means of substituents positions, side chain conformations and ring puckering led us to a new "eight-conformer hypothesis" which describes interconversions among the most important sialyl cation conformers and predicts that stronger remote participation of acyl groups favors β-anomers. Thus, selective synthesis of the desired α-sialosides requires minimization of acyl groups participation.
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Affiliation(s)
- Maria V Panova
- Laboratory of Glycochemistry, N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky prospect 47, 119991, Moscow, Russian Federation
| | - Michael G Medvedev
- Group of Theoretical Chemistry, N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky prospect 47, 119991, Moscow, Russian Federation
| | - Anna V Orlova
- Laboratory of Glycochemistry, N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky prospect 47, 119991, Moscow, Russian Federation
| | - Leonid O Kononov
- Laboratory of Glycochemistry, N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky prospect 47, 119991, Moscow, Russian Federation
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3
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Zhao G, Li J, Wang T. Visible-light-induced photoacid catalysis: application in glycosylation with O-glycosyl trichloroacetimidates. Chem Commun (Camb) 2021; 57:12659-12662. [PMID: 34768281 DOI: 10.1039/d1cc04887b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The development of visible-light-induced photoacid catalyzed glycosylation is reported. The eosin Y and PhSSPh catalyst system is applied to realize glycosylation with different glycosyl donors upon light irradiation. The reaction shows a broad substrate scope, including both glycosyl donors and acceptors, and highlights the mild nature of the reaction conditions.
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Affiliation(s)
- Gaoyuan Zhao
- Department of Chemistry, University at Albany, State University of New York, 1400 Washington Avenue, Albany, New York 12222, USA.
| | - Juncheng Li
- Department of Chemistry, University at Albany, State University of New York, 1400 Washington Avenue, Albany, New York 12222, USA.
| | - Ting Wang
- Department of Chemistry, University at Albany, State University of New York, 1400 Washington Avenue, Albany, New York 12222, USA.
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4
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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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5
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Quirke JCK, Crich D. Side Chain Conformation Restriction in the Catalysis of Glycosidic Bond Formation by Leloir Glycosyltransferases, Glycoside Phosphorylases, and Transglycosidases. ACS Catal 2021; 11:5069-5078. [PMID: 34367723 PMCID: PMC8336929 DOI: 10.1021/acscatal.1c00896] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Carbohydrate side chain conformation is an important factor in the control of reactivity at the anomeric center, ie, in the making and breaking of glycosidic bonds, whether chemically or, for hydrolysis, by glycoside hydrolases. In nature glycosidic bond formation is catalyzed out by glycosyltransferases (GTs), glycoside phosphoryases, and transglycosidases. By analysis of 118 crystal structures of sugar nucleotide dependent (Leloir) GTs, 136 crystal structures of glycoside phosphorylases, and 54 crystal structures of transglycosidases bound to hexopyranosides or their analogs at the donor site (-1 site), we determined that most enzymes that catalyze glycoside synthesis, be they GTs, glycoside phosphorylases or transglycosidases, restrict their substrate side chains to the most reactive gauche,gauche (gg) conformation to achieve maximum stabilization of the oxocarbenium ion-like transition state for glycosyl transfer. The galactose series deviates from this trend, with α-galactosyltransferases preferentially restricting their substrates to the second-most reactive gauche,trans (gt) conformation, and β-galactosyltransferases favoring the least reactive trans,gauche (tg) conformation. This insight will help progress the design and development of improved, conformationally-restricted GT inhibitors that take advantage of these inherent side chain preferences.
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Affiliation(s)
- Jonathan C. K. Quirke
- 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
| | - 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
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6
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Crich D. En Route to the Transformation of Glycoscience: A Chemist's Perspective on Internal and External Crossroads in Glycochemistry. J Am Chem Soc 2021; 143:17-34. [PMID: 33350830 PMCID: PMC7856254 DOI: 10.1021/jacs.0c11106] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Carbohydrate chemistry is an essential component of the glycosciences and is fundamental to their progress. This Perspective takes the position that carbohydrate chemistry, or glycochemistry, has reached three crossroads on the path to the transformation of the glycosciences, and illustrates them with examples from the author's and other laboratories. The first of these potential inflexion points concerns the mechanism of the glycosylation reaction and the role of protecting groups. It is argued that the experimental evidence supports bimolecular SN2-like mechanisms for typical glycosylation reactions over unimolecular ones involving stereoselective attack on naked glycosyl oxocarbenium ions. Similarly, it is argued that the experimental evidence does not support long-range stereodirecting participation of remote esters through bridged bicyclic dioxacarbenium ions in organic solution in the presence of typical counterions. Rational design and improvement of glycosylation reactions must take into account the roles of the counterion and of concentration. A second crossroads is that between mainstream organic chemistry and glycan synthesis. The case is made that the only real difference between glycan and organic synthesis is the formation of C-O rather than C-C bonds, with diastereocontrol, strategy, tactics, and elegance being of critical importance in both areas: mainstream organic chemists should feel comfortable taking this fork in the road, just as carbohydrate chemists should traveling in the opposite direction. A third crossroads is that between carbohydrate chemistry and medicinal chemistry, where there are equally many opportunities for traffic in either direction. The glycosciences have advanced enormously in the past decade or so, but creativity, input, and ingenuity of scientists from all fields is needed to address the many sophisticated challenges that remain, not the least of which is the development of a broader and more general array of stereospecific glycosylation reactions.
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Affiliation(s)
- 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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7
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Jeanneret RA, Johnson SE, Galan MC. Conformationally Constrained Glycosyl Donors as Tools to Control Glycosylation Outcomes. J Org Chem 2020; 85:15801-15826. [DOI: 10.1021/acs.joc.0c02045] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Robin A. Jeanneret
- School of Chemistry, University of Bristol, Cantock’s
Close, Bristol BS8 1TS, United Kingdom
| | - Simon E. Johnson
- School of Chemistry, University of Bristol, Cantock’s
Close, Bristol BS8 1TS, United Kingdom
| | - M. Carmen Galan
- School of Chemistry, University of Bristol, Cantock’s
Close, Bristol BS8 1TS, United Kingdom
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8
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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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9
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Ngoje P, Crich D. Stereocontrolled Synthesis of the Equatorial Glycosides of 3-Deoxy-d-manno-oct-2-ulosonic Acid: Role of Side Chain Conformation. J Am Chem Soc 2020; 142:7760-7764. [PMID: 32275429 DOI: 10.1021/jacs.0c03215] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The pseudosymmetric relationship of the bacterial sialic acid, pseudaminic acid, and 3-deoxy-d-manno-oct-2-ulosonic acid (KDO) affords the hypothesis that suitably protected KDO donors will adopt the trans, gauche conformation of their side chain and consequently be highly equatorially selective in their coupling reactions conducted at low temperature. This hypothesis is borne out by the synthesis, conformational analysis, and excellent equatorial selectivity seen on coupling of per-O-acetyl or benzyl-protected KDO donors in dichloromethane at -78 °C. Mechanistic understanding of glycosylation reactions is advancing to a stage at which predictions of selectivity can be made. In this instance, predictions of selectivity provide the first highly selective entry into KDO equatorial glycosides such as are found in the capsular polysaccharides of numerous pathogenic bacteria.
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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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10
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Bartolo ND, Read JA, Valentín EM, Woerpel KA. Reactions of Allylmagnesium Reagents with Carbonyl Compounds and Compounds with C═N Double Bonds: Their Diastereoselectivities Generally Cannot Be Analyzed Using the Felkin-Anh and Chelation-Control Models. Chem Rev 2020; 120:1513-1619. [PMID: 31904936 PMCID: PMC7018623 DOI: 10.1021/acs.chemrev.9b00414] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
This review describes the additions of allylmagnesium reagents to carbonyl compounds and to imines, focusing on the differences in reactivity between allylmagnesium halides and other Grignard reagents. In many cases, allylmagnesium reagents either react with low stereoselectivity when other Grignard reagents react with high selectivity, or allylmagnesium reagents react with the opposite stereoselectivity. This review collects hundreds of examples, discusses the origins of stereoselectivities or the lack of stereoselectivity, and evaluates why selectivity may not occur and when it will likely occur.
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Affiliation(s)
- Nicole D. Bartolo
- Department of Chemistry, New York University, 100
Washington Square East, New York, NY 10003, USA
| | - Jacquelyne A. Read
- Department of Chemistry, New York University, 100
Washington Square East, New York, NY 10003, USA
- Department of Chemistry, University of Utah, 315 South 1400
East, Salt Lake City, UT 84112, USA
| | - Elizabeth M. Valentín
- Department of Chemistry, New York University, 100
Washington Square East, New York, NY 10003, USA
- Department of Chemistry, Susquehanna University, 514
University Avenue, Selinsgrove, PA 17870, USA
| | - K. A. Woerpel
- Department of Chemistry, New York University, 100
Washington Square East, New York, NY 10003, USA
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11
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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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12
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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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13
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Panova MV, Orlova AV, Kononov LO. Stabilization of sialyl cation in axial conformation assisted by remote acyl groups. Russ Chem Bull 2018. [DOI: 10.1007/s11172-018-2260-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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14
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Dhakal B, Crich D. Synthesis and Stereocontrolled Equatorially Selective Glycosylation Reactions of a Pseudaminic Acid Donor: Importance of the Side-Chain Conformation and Regioselective Reduction of Azide Protecting Groups. J Am Chem Soc 2018; 140:15008-15015. [PMID: 30351022 DOI: 10.1021/jacs.8b09654] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Pseudaminic acid is an amino deoxy sialic acid whose glycosides are essential components of many pathogenic Gram-negative bacterial cell walls including those from Pseudomonas aeruginosa, Vibrio cholerae, Campylobacter jejuni, Campylobacter coli, Vibrio vulnificus, and Pseudoalteromonas distincta. The study of pseudaminic acid glycosides is however hampered by poor availability from nature and the paucity of good synthetic methods and limited to no understanding of the factors controlling stereoselectivity. Conformational analysis of the side chains of various stereoisomeric sialic acids suggested that the side chain of pseudaminic acid would take up the most electron-withdrawing trans, gauche-conformation, as opposed to the gauche, gauche conformation of N-acetyl neuraminic acid and the gauche, trans-conformtion of 7- epi N-acetyl neuraminic acid, leading to the prediction of high equatorial selectivity. This prediction is borne out by the synthesis of a suitably protected pseudaminic acid donor from N-acetyl neuraminic acid in 20 steps and 5% overall yield and by the exquisite equatorial selectivity it displays in coupling reactions with typical glycosyl acceptors. The selectivity of the glycosylation reactions is further buttressed by the development and implementation of conditions for the regioselective release of the two amines from the corresponding azides, such as required for the preparation of the lipopolysaccharides. These findings open the way to the synthesis and study of pseudaminic acid-based bacterial lipopolysaccharides and, importantly in the broader context of glycosylation reactions in general, underline the significant role played by side-chain conformation in the control of reactivity and selectivity.
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Affiliation(s)
- Bibek Dhakal
- 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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15
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Wen P, Crich D. Allylic Strain as a Stereocontrol Element in the Hydrogenation of 3-Hydroxymethyl-cyclohex-3-en-1,2,5-triol Derivatives. Synthesis of the Carbasugar Pseudo-2-deoxy-α-D-glucopyranose. Tetrahedron 2018; 74:5183-5191. [PMID: 30505021 DOI: 10.1016/j.tet.2018.04.078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
By adaptation of a literature method developed in the glucose series and standard protecting group manipulations a 2-deoxy-D-glucose derivative is converted to a series of 1R,2R,5R-3-hydroxymethyl-cyclohexen-1,2,5-triol derivatives whose reduction to the corresponding diastereomeric D-gluco and L-ido-2-deoxy carbasugars is studied. When the hydroxymethyl group is tied up in a cyclic isopropylidene acetal with the adjacent 6-hydroxy group the cis-fused products with the ido-configuration are formed preferentially whereas protection of the hydroxymethyl group as a methoxymethyl ether results in the formation of the D-gluco isomer on hydrogenation over Raney nickel. This result is rationalized in terms of the minimization of allylic strain in the course of the reduction, enables the preparation of the carbasugar pseudo-2-deoxy-α-D-glucopyranose, and suggests that the conformation of the side chain is an important control element in the chemistry of the pseudosugars as it is in the sugars themselves.
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Affiliation(s)
- Peng Wen
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202, USA
| | - David Crich
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202, USA
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16
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Abstract
Deoxy-sugars often play a critical role in modulating the potency of many bioactive natural products. Accordingly, there has been sustained interest in methods for their synthesis over the past several decades. The focus of much of this work has been on developing new glycosylation reactions that permit the mild and selective construction of deoxyglycosides. This Review covers classical approaches to deoxyglycoside synthesis, as well as more recently developed chemistry that aims to control the selectivity of the reaction through rational design of the promoter. Where relevant, the application of this chemistry to natural product synthesis will also be described.
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Affiliation(s)
- Clay S. Bennett
- Department
of Chemistry, Tufts University, 62 Talbot Avenue, Medford, Massachusetts 02155, United States
| | - M. Carmen Galan
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
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17
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Adero PO, Amarasekara H, Wen P, Bohé L, Crich D. The Experimental Evidence in Support of Glycosylation Mechanisms at the S N1-S N2 Interface. Chem Rev 2018; 118:8242-8284. [PMID: 29846062 PMCID: PMC6135681 DOI: 10.1021/acs.chemrev.8b00083] [Citation(s) in RCA: 213] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A critical review of the state-of-the-art evidence in support of the mechanisms of glycosylation reactions is provided. Factors affecting the stability of putative oxocarbenium ions as intermediates at the SN1 end of the mechanistic continuum are first surveyed before the evidence, spectroscopic and indirect, for the existence of such species on the time scale of glycosylation reactions is presented. Current models for diastereoselectivity in nucleophilic attack on oxocarbenium ions are then described. Evidence in support of the intermediacy of activated covalent glycosyl donors is reviewed, before the influences of the structure of the nucleophile, of the solvent, of temperature, and of donor-acceptor hydrogen bonding on the mechanism of glycosylation reactions are surveyed. Studies on the kinetics of glycosylation reactions and the use of kinetic isotope effects for the determination of transition-state structure are presented, before computational models are finally surveyed. The review concludes with a critical appraisal of the state of the art.
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Affiliation(s)
- Philip Ouma Adero
- 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
| | - Peng Wen
- Department of Chemistry , Wayne State University , 5101 Cass Avenue , Detroit , Michigan 48202 , United States
| | - Luis Bohé
- Institut de Chimie des Substances Naturelles, CNRS UPR 2301 , Université Paris-Sud Université Paris-Saclay , 1 avenue de la Terrasse , 91198 Gif-sur-Yvette , France
| | - David Crich
- Department of Chemistry , Wayne State University , 5101 Cass Avenue , Detroit , Michigan 48202 , United States
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18
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Yang B, Yang W, Ramadan S, Huang X. Pre-activation Based Stereoselective Glycosylations. European J Org Chem 2018; 2018:1075-1096. [PMID: 29805297 PMCID: PMC5963711 DOI: 10.1002/ejoc.201701579] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Indexed: 12/19/2022]
Abstract
Due to the wide presence of carbohydrates in nature and their crucial roles in numerous important biological processes, oligosaccharides have attracted a lot of attention in synthetic organic chemistry community. Many innovative synthetic methods have been developed for oligosaccharide synthesis, among which the pre-activation based glycosylation is particularly noteworthy. Traditionally, glycosylation reactions are carried out when the glycosyl donor and the acceptor are both present when the promoter is added. In comparison, the pre-activation based glycosylation is unique, where the glycosyl donor is activated by the promoter in the absence of the acceptor. Upon complete donor activation, the acceptor is added to the reaction mixture enabling glycosylation. The key step in any oligosaccharide synthesis is the stereoselective formation of the glycosidic bond. As donor activation and acceptor glycosylation are temporally separated, pre-activation based glycosylation can bestow unique stereochemical control. This review systematically discusses factors impacting the stereochemical outcome of a pre-activation based glycosylation reaction including substituents on the glycosyl donor, reaction solvent, and additives. Applications of pre-activation based stereoselective glycosylation in assembly of complex oligosaccharides are also discussed.
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Affiliation(s)
- Bo Yang
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, MI 48824 USA
| | - Weizhun Yang
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, MI 48824 USA
| | - Sherif Ramadan
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, MI 48824 USA
- Chemistry Department, Faculty of Science, Benha University, Benha, Qaliobiya 13518, Egypt
| | - Xuefei Huang
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, MI 48824 USA
- Department of Biomedical Engineering, Michigan State University, East Lansing, MI 48824 USA
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI 48824 USA
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19
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Parent JF, Deslongchamps P. Bent bonds (τ) and the antiperiplanar hypothesis, and the reactivity at the anomeric center in pyranosides. Org Biomol Chem 2018; 14:11183-11198. [PMID: 27834970 DOI: 10.1039/c6ob02263d] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The stereoselectivity of nucleophilic addition on oxocarbenium ions derived from the bicyclic pyranoside model with or without a C2-OR group can be understood through the use of the bent-bond and the antiperiplanar hypothesis in conjunction with the concept of hyperconjugation as an alternative interpretive model of structure and reactivity.
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Affiliation(s)
- Jean-François Parent
- Département de chimie, Faculté des sciences et de génie, Université Laval, Pavillon Alexandre-Vachon, 1045 avenue de la médecine, Québec, Québec G1V 0A6, Canada.
| | - Pierre Deslongchamps
- Département de chimie, Faculté des sciences et de génie, Université Laval, Pavillon Alexandre-Vachon, 1045 avenue de la médecine, Québec, Québec G1V 0A6, Canada.
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20
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Amarasekara H, Dharuman S, Kato T, Crich D. Synthesis of Conformationally-Locked cis- and trans-Bicyclo[4.4.0] Mono-, Di-, and Trioxadecane Modifications of Galacto- and Glucopyranose; Experimental Limiting 3J H,H Coupling Constants for the Estimation of Carbohydrate Side Chain Populations and Beyond. J Org Chem 2018; 83:881-897. [PMID: 29241001 PMCID: PMC5775050 DOI: 10.1021/acs.joc.7b02891] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Hexopyranose side chains populate three staggered conformations, whose proportions can be determined from the three sets of ideal limiting 3JH5,H6R and 3JH5,H6S coupling constants in combination with the time-averaged experimental coupling constants. Literature values for the limiting coupling constants, obtained by the study of model compounds, the use of the Haasnoot-Altona and related equations, or quantum mechanical computations, can result in computed negative populations of one of the three ideal conformations. Such values arise from errors in the limiting coupling constants and/or from the population of nonideal conformers. We describe the synthesis and analysis of a series of cis- and trans-fused mono-, di-, and trioxabicyclo[4.4.0]octane-like compounds. Correction factors for the application of data from internal models (-CH(OR)-CH(OR)-) to terminal systems (-CH(OR)-CH2(OR)) are deduced from comparison of further models, and applied where necessary. Limiting coupling constants so-derived are applied to the side chain conformations of three model hexopyranosides, resulting in calculated conformer populations without negative values. Although, developed primarily for hexopyranose side chains, the limiting coupling constants are suitable, with the correction factors presented, for application to the side chains of higher carbon sugars and to conformation analysis of acyclic diols and their derivatives in a more general sense.
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Affiliation(s)
- Harsha Amarasekara
- Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States
| | - Suresh Dharuman
- Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States
| | - Takayuki Kato
- Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States
| | - David Crich
- Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States
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21
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Affiliation(s)
- Ryan Williams
- School of Chemistry; University of Bristol; Cantock's Close BS8 1TS Bristol U.K
| | - M. Carmen Galan
- School of Chemistry; University of Bristol; Cantock's Close BS8 1TS Bristol U.K
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22
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Podvalnyy NM, Malysheva NN, Panova MV, Zinin AI, Chizhov AO, Orlova AV, Kononov LO. Stereoselective sialylation with O-trifluoroacetylated thiosialosides: hydrogen bonding involved? Carbohydr Res 2017; 451:12-28. [PMID: 28934626 DOI: 10.1016/j.carres.2017.09.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Revised: 09/05/2017] [Accepted: 09/05/2017] [Indexed: 01/05/2023]
Abstract
A series of novel sialyl donors containing O-trifluoroacetyl (TFA) groups at various positions was synthesized. The choice of protecting groups in sialyl donors was based on hypothesis that variations in ability of different acyl groups to act as hydrogen bond acceptors would influence the supramolecular structure of reaction mixture (solution structure), hence the outcome of sialylation. These glycosyl donors were examined in the model glycosylation of the primary hydroxyl group of 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose in comparison with sialyl donors without O-TFA groups. The presence of O-TFA groups in a sialyl donor strongly affected the outcome of sialylation. Several sialyl donors studied showed promising results: yields of disaccharides can be as high as 86% as can be the stereoselectivities (α/β up to 15:1). The results obtained suggest that varying acyl O-protecting groups in sialyl donor may result in dramatic changes in the outcome of sialylation although further studies are required to dissect the influence of intermolecular hydrogen bonding and intramolecular substituent effects related to variations of electron-withdrawing properties of different acyl groups.
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Affiliation(s)
- Nikita M Podvalnyy
- N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Leninsky prosp., 47, 119991 Moscow, Russian Federation
| | - Nelly N Malysheva
- N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Leninsky prosp., 47, 119991 Moscow, Russian Federation
| | - Maria V Panova
- N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Leninsky prosp., 47, 119991 Moscow, Russian Federation
| | - Alexander I Zinin
- N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Leninsky prosp., 47, 119991 Moscow, Russian Federation
| | - Alexander O Chizhov
- N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Leninsky prosp., 47, 119991 Moscow, Russian Federation
| | - Anna V Orlova
- N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Leninsky prosp., 47, 119991 Moscow, Russian Federation
| | - Leonid O Kononov
- N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Leninsky prosp., 47, 119991 Moscow, Russian Federation.
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23
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Abstract
Pd(MeCN)2Cl2 enables the α-stereoselective catalytic synthesis of 2,3-unsaturated O-glycosides from O(3)-acylated glycals without the requirement for additives to preactivate either donor or nucleophile. Mechanistic studies suggest that, unlike traditional (η3-allyl)palladium-mediated processes, the reaction proceeds via an alkoxy-palladium intermediate that increases the proton acidity and oxygen nucleophilicity of the alcohol. The method is exemplified with the synthesis of a range of glycosides and glycoconjugates of synthetic utility.
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Affiliation(s)
- Abhijit Sau
- School of Chemistry, University of Bristol , Cantock's Close, Bristol, BS8 1TS, United Kingdom
| | - M Carmen Galan
- School of Chemistry, University of Bristol , Cantock's Close, Bristol, BS8 1TS, United Kingdom
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24
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Zhou J, Lv S, Zhang D, Xia F, Hu W. Deactivating Influence of 3-O-Glycosyl Substituent on Anomeric Reactivity of Thiomannoside Observed in Oligomannoside Synthesis. J Org Chem 2017; 82:2599-2621. [DOI: 10.1021/acs.joc.6b03017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Jun Zhou
- Shanghai Engineering Research
Center of Molecular Therapeutics and New Drug Development, School
of Chemistry and Molecular Engineering, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China
| | - Siying Lv
- Shanghai Engineering Research
Center of Molecular Therapeutics and New Drug Development, School
of Chemistry and Molecular Engineering, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China
| | - Dan Zhang
- Shanghai Engineering Research
Center of Molecular Therapeutics and New Drug Development, School
of Chemistry and Molecular Engineering, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China
| | - Fei Xia
- Shanghai Engineering Research
Center of Molecular Therapeutics and New Drug Development, School
of Chemistry and Molecular Engineering, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China
| | - Wenhao Hu
- Shanghai Engineering Research
Center of Molecular Therapeutics and New Drug Development, School
of Chemistry and Molecular Engineering, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China
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25
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Bols M, Pedersen CM. Silyl-protective groups influencing the reactivity and selectivity in glycosylations. Beilstein J Org Chem 2017; 13:93-105. [PMID: 28228850 PMCID: PMC5301963 DOI: 10.3762/bjoc.13.12] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 12/23/2016] [Indexed: 11/26/2022] Open
Abstract
Silyl groups such as TBDPS, TBDMS, TIPS or TMS are well-known and widely used alcohol protective groups in organic chemistry. Cyclic silylene protective groups are also becoming increasingly popular. In carbohydrate chemistry silyl protective groups have frequently been used primarily as an orthogonal protective group to the more commonly used acyl and benzyl protective groups. However, silyl protective groups have significantly different electronic and steric requirements than acyl and alkyl protective groups, which particularly becomes important when two or more neighboring alcohols are silyl protected. Within the last decade polysilylated glycosyl donors have been found to have unusual properties such as high (or low) reactivity or high stereoselectivity. This mini review will summarize these findings.
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Affiliation(s)
- Mikael Bols
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
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26
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Dhakal B, Buda S, Crich D. Stereoselective Synthesis of 5-epi-α-Sialosides Related to the Pseudaminic Acid Glycosides. Reassessment of the Stereoselectivity of the 5-Azido-5-deacetamidosialyl Thioglycosides and Use of Triflate as Nucleophile in the Zbiral Deamination of Sialic Acids. J Org Chem 2016; 81:10617-10630. [PMID: 27806203 PMCID: PMC5148678 DOI: 10.1021/acs.joc.6b02221] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
With a view to the eventual synthesis of glycosyl donors for the stereocontrolled synthesis of pseudaminic acid glycosides, the stereocontrolled synthesis of a d-glycero-d-gulo sialic acid adamantanylthioglycoside carrying an axial azide at the 5-position is described. The synthesis employs levulinic acid as nucleophile in the oxidative deamination of an N-acetylneuraminic acid thioglycoside leading to the formation of a 3-deoxy-d-glycero-d-galacto-2-nonulosonic acid (KDN) derivative selectively protected as 5-O-levulinate. Replacement of the levulinate by triflate enables introduction of the axial azide and hence formation of the glycosyl donor. A shorter synthesis uses trifluoromethanesulfonate as nucleophile in the oxidative deamination step when the 5-O-triflyl KDN derivative is obtained directly. Glycosylation reactions conducted with the 5-azido-d-glycero-d-gulo-configured sialyl adamantanylthioglycoside at -78 °C are selective for the formation of the equatorial glycosides, suggesting that the synthesis of equatorial pseudaminic acid glycosides will be possible as suitable donors become available. A comparable N-acetylneuraminic acid adamantanylthioglycoside carrying an equatorial azide at the 5-position was also found to be selective for equatorial glycoside formation under the same conditions, suggesting that reinvestigation of other azide-protected NeuAc donors is merited. Glycosylation stereoselectivity in the d-glycero-d-gulo series is discussed in terms of the side-chain conformation of the donor.
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Affiliation(s)
- Bibek Dhakal
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA
| | - Szymon Buda
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA
| | - David Crich
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA
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