Anomeric-Oxygen Activation for Glycoside Synthesis: The Trichloroacetimidate Method

Schmidt, Richard R.; Kinzy, Willy

doi:10.1016/s0065-2318(08)60150-x

Cited by 846 publications

(429 citation statements)

References 193 publications

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“…47,48 A TMSOTf-promoted glycosylation of glycosyl acceptor 12 with glycosyl donors 18 and 22 in DCM gave pentasaccharides 23 and 25, respectively, in excellent yields. Cleavage of the phthalimido group of 23 and 25 was accomplished by treatment with hydrazine in ethanol, which was followed by N-acetylation with acetic anhydride in methanol to afford compounds 24 and 26, respectively.…”

Section: Oligosaccharide Synthesismentioning

confidence: 99%

Probing the Substrate Specificity of Golgi α-Mannosidase II by Use of Synthetic Oligosaccharides and a Catalytic Nucleophile Mutant

et al. 2008

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Inhibition of Golgi α-mannosidase II (GMII), which acts late in the N-glycan processing pathway, provides a route to blocking cancer-induced changes in cell surface oligosaccharide structures. To probe the substrate requirements of GMII, oligosaccharides were synthesized that contained an α(1,3)-or α(1,6)-linked 1-thiomannoside. Surprisingly, these oligosaccharides were not observed in X-ray crystal structures of native Drosophila GMII (dGMII). However, a mutant enzyme in which the catalytic nucleophilic aspartate was changed to alanine (D204A) allowed visualization of soaked oligosaccharides and led to the identification of the binding site for the α(1,3)-linked mannoside of the natural substrate. These studies also indicate that the conformational change of the bound mannoside to a high-energy B 2,5 conformation is facilitated by steric hindrance from, and the formation of strong hydrogen bonds to, Asp204. The observation that 1-thio-linked mannosides are not well tolerated by the catalytic site of dGMII led to the synthesis of a pentasaccharide containing the α(1,6)-linked Man of the natural substrate and the β(1,2)-linked GlcNAc moiety proposed to be accommodated by the extended binding site of the enzyme. A cocrystal structure of this compound with the D204A enzyme revealed the molecular interactions with the β(1,2)-linked GlcNAc. The structure is consistent with the ~80-fold preference of dGMII for the cleavage of substrates containing a nonreducing β(1,2)-linked GlcNAc. By contrast, the lysosomal mannosidase lacks an equivalent GlcNAc binding site and kinetic analysis indicates oligomannoside substrates without non-reducing-terminal GlcNAc modifications are preferred, suggesting that selective inhibitors for GMII could exploit the additional binding specificity of the GlcNAc binding site.

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Section: Oligosaccharide Synthesismentioning

confidence: 99%

Probing the Substrate Specificity of Golgi α-Mannosidase II by Use of Synthetic Oligosaccharides and a Catalytic Nucleophile Mutant

et al. 2008

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“…This method does not involve the use of heavy metals as promoters, what makes it the preferred one in the synthesis of 1,2-trans-glycosides, in opposition to the KoenigsKnorr method [147].…”

Section: Chemical Glycosidationmentioning

confidence: 99%

Occurrence, Biological Activities and Synthesis of Kaurane Diterpenes and their Glycosides

2007

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This paper presents a review on kaurane diterpenes and their glycoside derivatives, covering aspects of their occurrence, biological activities and the synthesis of these natural products and their analogues. First, it shows and classifies diterpenes, in accordance with the already established structural criteria in the literature. Then, kaurane diterpenes are presented, focusing on their chemical structures, occurrence in the plant kingdom and their main, recently described, biological activities. Moreover, the most significant works, published between 1964 and November 2006, which describe the total synthesis or structural transformations of some kaurane diterpenes, including either semisynthetic and/or microbiological methodologies, are consisely reviewed. At this point, some general considerations on glycosides are introduced, and kaurane glycosides are presented and discussed on the basis of their toxic importance and occurrence in the plant kingdom, having focused on related aspects of their biological activities and the relationships between these activities and the structural factors of their molecules. Finally, the principal methods of glycosidation by enzymatic and chemical processes are both presented, and a few papers on the synthesis of kaurane glycosides are succinctly discussed. Molecules 2007, 12 456

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“…Although several strategies have been developed for the β-mannopyranosylation, 14 the mannosyl 4-pentenoate/PhSeOTf method, 15 which is one of new glycosylation methods recently developed in our laboratory, 11,16 would be employed. In addition, the glycosyl trichloroacetimidate 17 as a donor would be used for the α-2-azidoglucopyranosylation.…”

Section: Resultsmentioning

confidence: 99%

Improved Synthesis of the Tetrasaccharide Repeat Unit of the O-Antigen Polysaccharide from Escherichia coli O77

Lee¹,

Baek²,

Jeon³

et al. 2007

Bulletin of the Korean Chemical Society

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The efficient synthesis of a tetrasaccharide, the suitably protected form of the repeat unit,of the O-antigen polysaccharide of the lipopolysaccharide from E. coli O77 has been accomplished. Glycosylation reactions for the coupling of four monosaccharide building blocks of the tetrasaccharide were carried out employing the CB glycoside method, the mannosyl 4-pentenoate/PhSeOTf method, and the glycosyl trichloroacetimidate method with complete stereoselectivities in excellent yields.

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Anomeric-Oxygen Activation for Glycoside Synthesis: The Trichloroacetimidate Method

Cited by 846 publications

References 193 publications

Probing the Substrate Specificity of Golgi α-Mannosidase II by Use of Synthetic Oligosaccharides and a Catalytic Nucleophile Mutant

Probing the Substrate Specificity of Golgi α-Mannosidase II by Use of Synthetic Oligosaccharides and a Catalytic Nucleophile Mutant

Occurrence, Biological Activities and Synthesis of Kaurane Diterpenes and their Glycosides

Improved Synthesis of the Tetrasaccharide Repeat Unit of the O-Antigen Polysaccharide from Escherichia coli O77

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