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Remmerswaal W, Elferink H, Houthuijs KJ, Hansen T, ter Braak F, Berden G, van der Vorm S, Martens J, Oomens J, van der Marel GA, Boltje TJ, Codée JDC. Anomeric Triflates versus Dioxanium Ions: Different Product-Forming Intermediates from 3-Acyl Benzylidene Mannosyl and Glucosyl Donors. J Org Chem 2024; 89:1618-1625. [PMID: 38235652 PMCID: PMC10845153 DOI: 10.1021/acs.joc.3c02262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 12/19/2023] [Accepted: 12/28/2023] [Indexed: 01/19/2024]
Abstract
Minimal structural differences in the structure of glycosyl donors can have a tremendous impact on their reactivity and the stereochemical outcome of their glycosylation reactions. Here, we used a combination of systematic glycosylation reactions, the characterization of potential reactive intermediates, and in-depth computational studies to study the disparate behavior of glycosylation systems involving benzylidene glucosyl and mannosyl donors. While these systems have been studied extensively, no satisfactory explanations are available for the differences observed between the 3-O-benzyl/benzoyl mannose and glucose donor systems. The potential energy surfaces of the different reaction pathways available for these donors provide an explanation for the contrasting behavior of seemingly very similar systems. Evidence has been provided for the intermediacy of benzylidene mannosyl 1,3-dioxanium ions, while the formation of the analogous 1,3-glucosyl dioxanium ions is thwarted by a prohibitively strong flagpole interaction of the C-2-O-benzyl group with the C-5 proton in moving toward the transition state, in which the glucose ring adopts a B2,5-conformation. This study provides an explanation for the intermediacy of 1,3-dioxanium ions in the mannosyl system and an answer to why these do not form from analogous glucosyl donors.
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Affiliation(s)
- Wouter
A. Remmerswaal
- Leiden
Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden 2300 RA, The Netherlands
| | - Hidde Elferink
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, Nijmegen 6525 AJ, The Netherlands
| | - Kas J. Houthuijs
- Institute
for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, Nijmegen 6525 ED, The Netherlands
| | - Thomas Hansen
- Leiden
Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden 2300 RA, The Netherlands
- Department
of Chemistry and Pharmaceutical Sciences, Amsterdam Institute of Molecular
and Life Sciences (AIMMS), Vrije Universiteit
Amsterdam, De Boelelaan
1108, Amsterdam 1081 HZ, The Netherlands
| | - Floor ter Braak
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, Nijmegen 6525 AJ, The Netherlands
| | - Giel Berden
- Institute
for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, Nijmegen 6525 ED, The Netherlands
| | - Stefan van der Vorm
- Leiden
Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden 2300 RA, The Netherlands
| | - Jonathan Martens
- Institute
for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, Nijmegen 6525 ED, The Netherlands
| | - Jos Oomens
- Institute
for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, Nijmegen 6525 ED, The Netherlands
| | | | - Thomas J. Boltje
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, Nijmegen 6525 AJ, The Netherlands
| | - Jeroen D. C. Codée
- Leiden
Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden 2300 RA, The Netherlands
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Abstract
The structural complexity of glycans poses a serious challenge in the chemical synthesis of glycosides, oligosaccharides and glycoconjugates. Glycan complexity, determined by composition, connectivity, and configuration far exceeds what nature achieves with nucleic acids and proteins. Consequently, glycoside synthesis ranks among the most complex tasks in organic synthesis, despite involving only a simple type of bond-forming reaction. Here, we introduce the fundamental principles of glycoside bond formation and summarize recent advances in glycoside bond formation and oligosaccharide synthesis.
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Affiliation(s)
- Conor J Crawford
- Department of Biomolecular Systems, Max Planck Institute for Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany.
| | - Peter H Seeberger
- Department of Biomolecular Systems, Max Planck Institute for Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany.
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany
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Wang Z, Poveda A, Zhang Q, Unione L, Overkleeft HS, van der Marel GA, Jesús JB, Codée JDC. Total Synthesis and Structural Studies of Zwitterionic Bacteroides fragilis Polysaccharide A1 Fragments. J Am Chem Soc 2023. [PMID: 37310804 DOI: 10.1021/jacs.3c03976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Zwitterionic polysaccharides (ZPSs) are exceptional carbohydrates, carrying both positively charged amine groups and negatively charged carboxylates, that can be loaded onto MHC-II molecules to activate T cells. It remains enigmatic, however, how these polysaccharides bind to these receptors, and to understand the structural features responsible for this "peptide-like" behavior, well-defined ZPS fragments are required in sufficient quantity and quality. We here present the first total synthesis of Bacteroides fragilis PS A1 fragments encompassing up to 12 monosaccharides, representing three repeating units. Key to our successful syntheses has been the incorporation of a C-3,C-6-silylidene-bridged "ring-inverted" galactosamine building block that was designed to act as an apt nucleophile as well as a stereoselective glycosyl donor. Our stereoselective synthesis route is further characterized by a unique protecting group strategy, built on base-labile protecting groups, which has allowed the incorporation of an orthogonal alkyne functionalization handle. Detailed structural studies have revealed that the assembled oligosaccharides take up a bent structure, which translates into a left-handed helix for larger PS A1 polysaccharides, presenting the key positively charged amino groups to the outside of the helix. The availability of the fragments and the insight into their secondary structure will enable detailed interaction studies with binding proteins to unravel the mode of action of these unique oligosaccharides at the atomic level.
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Affiliation(s)
- Zhen Wang
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
- National Research Centre for Carbohydrate Synthesis, Jiangxi Normal University, 99 Ziyang Avenue, Nanchang 330022, China
| | - Ana Poveda
- CIC bioGUNE, Basque Research & Technology Alliance (BRTA), Bizkaia Technology Park, Building 800, 48162 Derio, Bizkaia, Spain
| | - Qingju Zhang
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
- National Research Centre for Carbohydrate Synthesis, Jiangxi Normal University, 99 Ziyang Avenue, Nanchang 330022, China
| | - Luca Unione
- CIC bioGUNE, Basque Research & Technology Alliance (BRTA), Bizkaia Technology Park, Building 800, 48162 Derio, Bizkaia, Spain
- Ikerbasque, Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Bizkaia, Spain
| | - Herman S Overkleeft
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Gijsbert A van der Marel
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Jiménez-Barbero Jesús
- CIC bioGUNE, Basque Research & Technology Alliance (BRTA), Bizkaia Technology Park, Building 800, 48162 Derio, Bizkaia, Spain
- Ikerbasque, Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Bizkaia, Spain
- Department of Organic Chemistry II, Faculty of Science and Technology, University of the Basque Country, EHU-UPV, 48940 Leioa, Spain
- Centro de Investigación Biomédica En Red de Enfermedades Respiratorias (CIBERES), 28029 Madrid, Spain
| | - Jeroen D C Codée
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
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