Galactopyranose pentaacetate

Epimerization of 4 at C-2 provided 5a-carba-a-DL-galactopyranose (6). When the pentaacetate IS was heated in acetic acid containing sulfuric acid, epimerization occurred at C-2 through an intermediary cyclic acetoxonium ion (18), with anchimeric assistance of the vicinal, axial acetoxyl group. After acetylation, 5a-carba-a-DL-galactopyranose pentaacetate (19) was obtained in a yield of 14% it was converted into 6 by hydrolysis. The antimicrobial activity of the racemate 6 was found to be about half that of the natural antibiotic 7 in the same assay system, indicating that the L-antipode is probably inactive. " ... 

The reaction of methyl glycopyranosides with sulfuryl chloride has also provided a route to 6-chloro (and other monochloro, dichloro, and trichloro) derivatives. 44 Schlubach and Wagenitz 44 observed that reaction of /3-d-galactopyranose pentaacetate with hydrogen bromide affords a 1,6-dibromo derivative which they converted into crystalline D-fucose in two steps. 

D-Arabinopyranose tetraacetate Methyl D-arabinopyranoside triacetate D-Galactopyranose pentaacetate Methyl 2,3-di-0-acetyl-4,6-0-benzylidene-a-D-galactopyranoside... 

Attempted alkylation of 2-pyridones often leads to mixtures of N- and O-alkylated products with the selectivity dependent on the reaction conditions. Alkylation of the sodium salt of 2-pyridone often leads to iV-alkylation while alkylation of the silver salt results in O-alkylation. For example, /3-D-galactopyranose pentaacetate reacts with silver 2-pyridoxide in toluene under reflux to give the pyridylgalactopyranoside 100 in good yield (Equation 67) <2001T3267>. 

Synonyms /f-o-Galactopyranose pentaacetate /f-D-Galactose Source Raveendran, R Wallen, S. L. 

Another instance where the choice of column is critical is with 6-0-methyl-D-galactitol (1-O-methyl-L-galactitol) pentaacetate and jS-n-galactopyranose pentaacetate, which are not separated on a column of 20% of Apiezon M, but are resolved by a liquid phase containing 5% of Apiezon M and 1% of poly (ethylene ycol). ... 

The synthesis of a,(3-D-galactopyranose pentaacetate using iodine as a Lewis acid [6]. 

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