Acetylated glycosides

Systematic studies of the acetolysis of disaccharides have been performed.57-803 Lindberg81,82 showed that anomerization and acetolysis of acetylated glycosides is retarded by the presence of electronegative groups in the aglycon. A mechanism involving an acyclic intermediate (20) was proposed for these reactions (see Scheme 2). 

K. Leontein, B. Lindberg, and J. Lonngren, Assignment of absolute configuration of sugars by g.l.c. of their acetylated glycosides formed from chiral alcohols, Carbohydr. Res., 62 (1978) 359—362. 

Yokoyama, Y, Hanamoto, T, Jin, X L, Jin, Y Z, Inanaga, J, Perchloric acid in 1,4-dioxane and perfluoro-octanesulfonic acid as practical catalysts for the stereoselective glycosylation of 1-0-acetyl-glycosides. Heterocycles, 52, 1203-1206, 2000. 

To a solution of 300 mg of 3-methoxy-2(lH)-pyridine and 386 mg of Bu NBr in 5 mL of 1 Al NaOH was added a solution of 440 mg of the crude chloride in 5 naL of CHjClj. The mixture was vigorously stirred at room temperature until the chloride completely disappeared (1 h). The water layer was separated, extracted with CH2CI2 the combined organic layer was processed as usual, and the product was purified by flash chromatography on silica gel to give the pure acetylated glycoside (100 mg, 18%). 

C. Denekamp and Y. Sandlers, Anomeric distinction and oxonium ion formation in acetylated glycosides, J. Mass Spectrom., 40 (2005) 765-771. 

The acetylated glycosides are deprotected by alkaline methanolysis at room temperature with methanol containing about 1% of CH3ONa. The acetyl groups, transfered onto the solvent, give the volatile methyl acetate. The anomeric... 

The assignment of absolute configuration has been established by separation of the two enantiomers by gas chromatography of the acetylated glycosides of the chiral alcohol (+)-octanol92 or the trimethylsilylated(-)-2-butyl glycosides.93... 

B. Lindberg, Action of strong acids on acetylated glycosides. V. Synthesis of (S-isomaltose octaacetate, Acta Chem. Scand., 3 (1949) 1355-1357. 

Some of the most important syntheses of glycosides start from glycosyl halides, which are converted into acetylated glycosides, with Walden inversion, by reaction with alcohols or phenols in the presence of acid-binding compounds. For example, methyl tetra-0-acetyl-/ -D-glucoside is obtained from a-aceto-bromoglucose by this method (the Koenigs-Knorr reaction) 942... 

Reaction and Purification Conditions and Yield for the Preparation of Fatty Acid Methyl Ester Acetylated Glycoside Ethers According to Method 1... 

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