A selective ring opening reaction of 4,6-O-benzylidene acetals in carbohydrates using trialkylsilane derivatives

Sakagami, Masahiro; Hamana, Hiroshi

doi:10.1016/s0040-4039(00)00877-7

Cited by 148 publications

(109 citation statements)

References 24 publications

Supporting

Mentioning

107

Contrasting

Unclassified

Order By: Relevance

“…Conventional procedures such as treatment with BH 3 ·THF/Bu 2 BOTf or BH 3 ·THF/TMSOTf [31] resulted in a loss of the Alloc group. Fortunately, the reaction of 11 with triethyl silane and PhBCl 2 in the presence of molecular sieves at −75°C [32] gave 5 in an excellent yield of 94% as only the C-6 hydroxyl.…”

Section: Chemical Synthesismentioning

confidence: 99%

Innate Immune Responses of Synthetic Lipid A Derivatives of Neisseria meningitidis

Zhang

Gaekwad

Wolfert

et al. 2007

Chemistry A European J

View full text Add to dashboard Cite

Differences in the pattern and chemical nature of fatty acids of lipid A of Neisseria meningitides lipooligosaccharides (LOS) and Escherichia coli lipopolysaccharides (LPS) may account for differences in inflammatory properties. Furthermore, there are indications that dimeric 3-deoxy-Dmanno-oct-2-ulosonic acid (KDO) moieties of LOS and LPS enhance biological activities. Heterogeneity in the structure of lipid A and possible contaminations with other inflammatory components have made it difficult to confirm these observations. To address these problems, a highly convergent approach for the synthesis of a lipid A derivative containing KDO has been developed, which relies on the ability to selectively remove or unmask in a sequential manner an isopropylidene acetal, 9-fluorenylmethoxycarbonyl (Fmoc), allyloxycarbonate (Alloc), azide, and thexyldimethylsilyl (TDS) ether. The strategy was employed for the synthesis of N. meningitidis lipid A containing KDO (3). Mouse macrophages were exposed to the synthetic compound and its parent LOS, E. coli lipid A (2), and a hybrid derivative (4) that has the asymmetrical acylation pattern of E. coli lipid A, but the shorter lipids of meningococcal lipid A. The resulting supernatants were examined for tumor necrosis factor alpha (TNF-α) and interferon beta (IFN-β) production. The lipid A derivative containing KDO was much more active than lipid A alone and just slightly less active than its parent LOS, indicating that one KDO moiety is sufficient for full activity of TNF-α and IFN-β induction. The lipid A of N. meningitidis was a significantly more potent inducer of TNF-α and IFN-β than E. coli lipid A, which is due to a number of shorter fatty acids. The compounds did not demonstrate a bias towards a MyD88-or TRIF-dependent response.

show abstract

Section: Chemical Synthesismentioning

confidence: 99%

Innate Immune Responses of Synthetic Lipid A Derivatives of Neisseria meningitidis

Zhang

Gaekwad

Wolfert

et al. 2007

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…Product 3 served as the glycosyl acceptor in the reaction with thiofucoside [17] 4 under modified in situ anomerization conditions. [18] Regioselective opening of acetal 5 was performed with triethylsilane/trifluoromethanesulfonic acid [19] to give 6, which was subsequently glycosylated with galactosyl trichloroacetimidate [13] 7 to furnish the Lewis x trisaccharides 8.…”

mentioning

confidence: 99%

Total Synthesis of the Glycopeptide Recognition Domain of the P‐Selectin Glycoprotein Ligand 1

2008

View full text Add to dashboard Cite

Block glycosylation of a T antigen–threonine conjugate with a sialyl Lewisx trichloroacetimidate was used to synthesize a sialyl Lewisx–T antigen–threonine building block. Selective protecting‐group manipulations furnished a compound with exclusively acetyl‐protected functions in the carbohydrate portion; this intermediate is sufficiently acid‐stable that it is applicable to the solid‐phase synthesis of binding site A of the P‐selectin ligand PSGL‐1.

show abstract

“…2,3-Oxazolidinone-protected compound 6 was formed after treatment of 5 with sodium hydride followed by acetylation. The reductive cleavage of the benzylidene acetal in 6 by using Et 3 SiH/TfOH [18] provided acceptor 7 with a free hydroxyl group at the 4 position.…”

Section: Resultsmentioning

confidence: 99%

A Highly α‐Stereoselective Synthesis of Oligosaccharide Fragments of the Vi Antigen from Salmonella typhi and Their Antigenic Activities

Yang

Zhu

Zheng

et al. 2011

Chemistry A European J

View full text Add to dashboard Cite

In this paper, a convenient approach to the synthesis of the repeating α-(1→4)-linked N-acetyl galactosaminuronic acid units from the capsular polysaccharide of Salmonella typhi is reported. The exclusively α-stereoselective glycosylation reactions were achieved by using oxazolidinone-protected glycosides as building blocks based on a pre-activation protocol. Di-, tri-, and tetrasaccharides were prepared by this short and efficient approach in high yields. The enzyme-linked immunosorbent assay experiments show that our synthetic tri- and tetrasaccharide had much higher antigenic activities than previously reported ones in the inhibition of antibody binding by the native polysaccharide. The results demonstrate that the antigenic activities of saccharides can be strengthened greatly by increasing the number of acetyl groups present.

show abstract

A selective ring opening reaction of 4,6-O-benzylidene acetals in carbohydrates using trialkylsilane derivatives

Cited by 148 publications

References 24 publications

Innate Immune Responses of Synthetic Lipid A Derivatives of Neisseria meningitidis

Innate Immune Responses of Synthetic Lipid A Derivatives of Neisseria meningitidis

Total Synthesis of the Glycopeptide Recognition Domain of the P‐Selectin Glycoprotein Ligand 1

A Highly α‐Stereoselective Synthesis of Oligosaccharide Fragments of the Vi Antigen from Salmonella typhi and Their Antigenic Activities

Contact Info

Product

Resources

About