The influence of boric acid on the acetylation of aldoses: ‘one-pot’ syntheses of penta-O-acetyl-β-D-glucofuranose and its crystalline propanoyl analogue
作者:Richard H. Furneaux、Phillip M. Rendle、Ian M. Sims
DOI:10.1039/b002841j
日期:——
When glucose and boric acid are heated in acetic acid a soluble compound forms from which, with acetic anhydride and catalytic amounts of sulfuric acid, a mixture consisting of >90% of the glucofuranose per-acetates (αâ¶Î² ratio 1â¶1.8) is obtained in high yield. In the absence of the sulfuric acid partial acetylation takes place and penta-O-acetyl-β-D-glucofuranose (αâ¶Î² ratio 1â¶52) is obtainable in good yield by removal of boric acid and completion of the esterification by addition of acetic anhydride and pyridine. A new, crystalline glucofuranose, penta-O-propanoyl-β-D-glucofuranose, is obtained in 58% yield in a âone-potâ procedure using boric acid.
The effects of boric acid on the acid-catalysed acetylation of other aldo-hexoses and -pentoses suggest that the synthesis of furanosyl per-esters could be successful with xylose and idose as well as with glucose.
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An improved method for the synthesis of anhydroalditols
作者:Arlen Jeffery、Vasu Nair
DOI:10.1016/0040-4039(95)00618-m
日期:1995.5
An improvedsynthesis of anhydroalditols through reductive cleavage of acetylated carbohydrates is reported. The procedure appears to have generality. Ring rearrangements, which complicate some other reported procedures for the preparation of anhydroalditols, were not observed. The acetate protecting groups used were stable under the reaction conditions employed.
Convenient syntheses of symmetrical and unsymmetrical glycosyl carbodiimides and N,N-bis(glycosyl)cyanamides
作者:László Kovács、Erzsébet Ősz、Zoltán Györgydeák
DOI:10.1016/s0008-6215(02)00108-8
日期:2002.7
carbon disulfide under mild conditions (room temperature, short reaction time) leads to symmetrical glycosyl carbodiimides. Addition of bis(trimethylsilyl)carbodiimide to peracetylated aldoses under the influence of SnCl(4) afforded N,N-bis(glycosyl)cyanamides for the first time. Readily accessible unsymmetrical N,N'-bis(glycosyl)thioureas can be desulfurated and transformed into the corresponding carbodiimides
A set of 1,3-propanediamine derivatives connected to carbohydrates (5) has been prepared in four steps from peracetylated sugar and 1,3-dibromo-2-propanol in 60-73% yields. D-Glucose, D-mannose, D-galactose, D-xylose, D-ribose, and maltose are utilized as sugar molecules in this work. The diamine moiety was connected to the C1 carbon of the glycopyranose ring via an O-glycoside bond. All of the anomeric