Recent topics in β-stereoselective mannosylation

Sasaki, Kaname; Tohda, Kazuki

doi:10.1016/j.tetlet.2017.12.077

Cited by 41 publications

(20 citation statements)

References 76 publications

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“…However, the stereoselective synthesis of β‐ l ‐rhamnosides has remained challenging due to the non‐availability of neighboring‐group participation as well as to the unfavorable anomeric effect and steric hindrance of the axial substituent at the C2 position . In addition, simply applying a stereoselective glycosylation strategy using a donor with 2,6‐, 3,6‐, or 4,6‐cyclic O‐protection directly to the β‐ l ‐rhamnopyranosylation (β‐ l ‐rhamnosylation) is difficult due to the deoxygenated C6 position. To overcome these problems, several approaches have been developed, and both indirect and direct methods have been developed ,.…”

Section: Methodsmentioning

confidence: 99%

Stereospecific β‐l‐Rhamnopyranosylation through an S_Ni‐Type Mechanism by Using Organoboron Reagents

et al. 2018

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Stereospecific β-l-rhamnopyranosylations were conducted using a 1,2-anhydro-l-rhamnopyranose donor and mono-ol or diol acceptors in the presence of a glycosyl-acceptor-derived borinic or boronic ester. Reactions proceeded smoothly to provide the corresponding β-l-rhamnopyranosides (β-l-Rhap) with complete stereoselectivity in moderate to high yields without any further additives under mild conditions. Mechanistic studies of the borinic ester mediated glycosylation using C kinetic isotope effect (KIE) measurements and DFT calculations were consistent with a concerted S i mechanism with an exploded transition state. In addition, the present glycosylation method was applied successfully to the synthesis of a trisaccharide, α-l-Rhap-(1,2)-β-l-Rhap-(1,4)-Glcp, derived from Streptococcus pneumoniae serotypes 7B, 7C, and 7D.

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Section: Methodsmentioning

confidence: 99%

Stereospecific β‐l‐Rhamnopyranosylation through an S_Ni‐Type Mechanism by Using Organoboron Reagents

et al. 2018

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“…An in‐depth analysis of the factors that affect the construction of 1,2‐ cis glycosidic bonds are illustrated by diverse authors. Demchenko and Sasaki's reviews highlighting the non‐reducing end elongation strategy are highly recommended readings …”

Section: Control Of Diastereoselectivity In the Synthesis Of 12‐glycmentioning

confidence: 99%

“…Obtaining 1,2‐ cis glycosidic bonds is always a difficult issue to cope with. The factors that affect stereoselectivity are being better understood in pyranosides than in furanosides . Although a variety of 1,2‐ cis stereocontrol methods have appeared i. e. intramolecular aglycon delivery (IAD), H‐bond‐mediated aglycone delivery (HAD) in flexible donors, or conformationally restrained methods, they are referred to non 2‐ O ‐glycosylated donors.…”

Section: Control Of Diastereoselectivity In the Synthesis Of 12‐glycmentioning

confidence: 99%

Intrinsic Issues in the Assembly of 1,2‐Linked Oligosaccharides

Kashiwagi

2020

Asian J Org Chem

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This review aims to highlight common issues involved in the assembly of 1,2-linked oligosaccharides. There is extensive literature on the subject, but most of the publications only address general oligosaccharides. Construction of 1,2-glycosidic linkage has an additional and intrinsic complexity due to its glycosylated O-2 position. Elongation of the fragment from reducing end curtails the possibility of using O-2 participating groups in the donor. The 2-Oglycosylated donors used in this context or in a convergent approach lead to the principal stereocontrol loss when 1,2trans gluco type or manno type linkage are targets. Only nonreducing end elongation strategy can ensure 1,2-trans linkage, but following a more expensive and cumbersome route. Archetypical cases where the convergent approach drove to a stereocontrol loss are presented. The perspective of this analysis attempts to complement Paulsen, Boons and Demchenko's masterworks about strategies in oligosaccharides synthesis. 2 3 4 5 6 7 8

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“…Structurally,t he O1A pentasaccharide contains two 1,2-cis-b-glycosidic linkages, which are difficult to form with high stereoselectivity due to an unfavorable anomeric effect and steric hindrance from the C2 axial group. [8] Thei nstallation of the b-rhamnosidic linkage is particularly challenging due to its 6-deoxy structure, which prevents the use of stereoselective glycosylation strategies using donors with 2,6-, 3,6-, or 4,6-cyclic Oprotection. [9] To overcome these problems,s ignificant efforts have been devoted to developing efficient b-rhamnosylation methods,a nd both indirect and direct methods have been developed.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of a Pentasaccharide Repeating Unit of Lipopolysaccharide Derived from Virulent E. coli O1 and Identification of a Glycotope Candidate of Avian Pathogenic E. coli O1

et al. 2020

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Avian pathogenic Escherichia coli (APEC) is ac ommon bacterial pathogen infecting chickens,r esulting in economic losses to the poultry industry worldwide.I np articular,APEC O1, one of the most common serotypes of APEC, is considered problematic due to its zoonotic potential. Therefore,m any attempts have been made to develop an effective vaccine against APEC O1. In fact, the lipopolysaccharide (LPS) O-antigen of APEC O1 has been shown to be apotent antigen for inducing specific protective immune responses. However,the detailed structure of the O-antigen of APEC O1 is not clear.T he present study demonstrates the first synthesis of ap entasaccharide repeating unit of LPS derived from virulent E. coli O1 and its conjugate with BSA. ELISA tests using the semi-synthetic glycoconjugate and the APEC O1 immune chicken serum revealed that the pentasaccharide is aglycotope candidate of APEC O1, with great potential as an antigen for vaccine development.

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Recent topics in β-stereoselective mannosylation

Cited by 41 publications

References 76 publications

Stereospecific β‐l‐Rhamnopyranosylation through an S_Ni‐Type Mechanism by Using Organoboron Reagents

Stereospecific β‐l‐Rhamnopyranosylation through an S_Ni‐Type Mechanism by Using Organoboron Reagents

Intrinsic Issues in the Assembly of 1,2‐Linked Oligosaccharides

Synthesis of a Pentasaccharide Repeating Unit of Lipopolysaccharide Derived from Virulent E. coli O1 and Identification of a Glycotope Candidate of Avian Pathogenic E. coli O1

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Recent topics in β-stereoselective mannosylation

Cited by 41 publications

References 76 publications

Stereospecific β‐l‐Rhamnopyranosylation through an SNi‐Type Mechanism by Using Organoboron Reagents

Stereospecific β‐l‐Rhamnopyranosylation through an SNi‐Type Mechanism by Using Organoboron Reagents

Intrinsic Issues in the Assembly of 1,2‐Linked Oligosaccharides

Synthesis of a Pentasaccharide Repeating Unit of Lipopolysaccharide Derived from Virulent E. coli O1 and Identification of a Glycotope Candidate of Avian Pathogenic E. coli O1

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Stereospecific β‐l‐Rhamnopyranosylation through an S_Ni‐Type Mechanism by Using Organoboron Reagents

Stereospecific β‐l‐Rhamnopyranosylation through an S_Ni‐Type Mechanism by Using Organoboron Reagents