ISSN:
0170-2041
Keywords:
Sialic acids
;
Thioketosides
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Various partially acetylated sialic acid α-ketosides were obtained without expensive protecting group techniques by using trimethyl orthoacetate or dimethylacetamide dimethyl acetal as acetylating agents or by performing a partial Zemplén de-O-acetylation. Using trimethyl orthoacetate as acetylating agents we synthesized 9-O-acetylated, 8-O-acetylated, and 8,9-di-O-acetylated sialic acid α-ketoside benzyl ester derivatives. The acetylation with dimethylacetamide dimethyl acetal yielded 9-O-acetylated, 8-O-acetylated, 4, 9-di-O-acetylated, 8,9-di-O-acetylated, and 4,8,9-tri-O-acetylated sialic acid α-ketoside benzyl ester derivatives. The partial Zemplén de-O-acetylation permitted the synthesis of 7,8,9-tri-O-acetylated sialic acid α-ketoside benzyl ester derivatives. After catalytic hydrogenation the 8-O-acetylated derivatives 2e and 3d were not stable and were completely converted into the 9-O-acetylated sialic acid α-thioketoside 2k. The N-acetyl-8,9-di-O-acetylneuraminic acid α-aminophenylthioketoside 21 showed a migration of the acetyl group from position 8 to position 7 in polar solvents, yielding a mixture of the 8,9-di-O- and the 7, 9-di-O-acetylated derivatives 21 and 2m in a molar ratio of approximately 1:1. The 7, 9-di-O-acetylated derivative 2m could be separated and was completely stable in methanol. Using the isopropylidene protecting group we could also prepare the 4-O-acetylated sialic acid α-thioketoside 2o. Treatment of the 9-O-acetylated derivative 2k with fluorescein isothiocyanate gave the fluorescent derivative 5.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.199419940214
Permalink
