Stereoselective Synthesis of α- and β-Glycosylamide Derivatives from Glycopyranosyl Azides via Isoxazoline Intermediates
摘要:
Treatment of 2-acetoxy glycopyranosyl azides with Ph3P gave isoxazolines by ring closure of the phosphorimine. Coupling of in situ generated isoxazolines with acylating reagents gave mixtures of alpha- or beta-glycopyranosyl amides. The alpha/beta ratio depended upon the acylating reagent and metal salts employed. For example, coupling of isoxazoline 3 with Z-Asp-(SPy)-OBn in the presence of CuCl2 gave exclusively alpha-N-glucopyranosylasparagine derivative 8. This general procedure has been applied to mono-, di-, and trisaccharide systems.
Iron(iii) chloride as an efficient catalyst for stereoselective synthesis of glycosyl azides and a cocatalyst with Cu(0) for the subsequent click chemistry
作者:Santosh B. Salunke、N. Seshu Babu、Chien-Tien Chen
DOI:10.1039/c1cc13370e
日期:——
A highly efficient and mild method for azido glycosylation of glycosyl β-peracetates to 1,2-trans glycosyl azides was developed by using inexpensive FeCl3 as the catalyst. In addition, we demonstrated, for the first time, that FeCl3 in combination with copper powder can promote 1,3-dipolar cycloaddition (click chemistry) of azido glycosides with terminal alkynes. Good to excellent yields were obtained with exclusive formation of a single isomer in both glycosyl azidation and subsequent cycloaddition processes.
The invention relates to novel compounds that have utility as inhibitors of heparan sulfate-binding proteins; compositions comprising the compounds, and use of the compounds and compositions thereof for the antiangiogenic, antimetastatic, anti-inflammatory, antimicrobial, anticoagulant and/or antithrombotic treatment of a mammalian subject.
Herein we report, for the first time, the successful anomeric azidation of per-O-acetylated and per-O-benzoylated sugars by catalytic amounts of oxophilic AuBr3 in good to excellent yields. The method is applicable to a wide range of easily accessible per-O-acetylated and per-O-benzoylated sugars. While reaction with per-O-acetylated and per-O-benzoylated monosaccharides was complete within 1–3 h at room temperature, the per-O-benzoylated disaccharides needed 2–3 h of heating at 55 °C.
(OA) was discovered as a mild influenza hemagglutinin (HA) inhibitor. Herein, as a further study, we report the preparation of a series of OA-saccharide conjugates via the CuAAC reaction, and the anti-influenza activity of these compounds was evaluated in vitro. Among them, compound 11b, an OA-glucose conjugate, showed a significantly increased anti-influenza activity with an IC50 of 5.47 μM, and no
A general synthetic way to incorporate oligosaccharides into [60]fullerene via cycloadditon and deacetylation is presented. The cycloaddition reaction in refluxing chlorobenzene gave a mixture of two unseparable stereoisomers of N-β-glycopyranosyl [5,6]-azafulleroids in 13∼28% yields for per-O-acetyl glycosyl azide of d-glucopyranose, d-galactopyranose, lactose, maltose, and maltotriose.