Chemical synthesis of α(2,8) octasialosides, the minimum structure of polysialic acids.

Chemical synthesis of an α(2,8) octasialic acid by using an N-acetyl-5-N,4-O:7-O,9-O-dicarbonyl protected sialyl donor is reported. The glycosyl donor underwent α-selective sialylation at the C8 hydroxyl group to give α(2,8) sialyl oligomers. The resulting oligosaccharides were then deprotected to give the fully deprotected α(2,8) octasialic acid without lacking the N-acetyl groups.

The α-Glycosidation of Partially Unprotected N-Acetyl and N-Glycolyl Sialyl Donors in the Absence of a Nitrile Solvent Effect.

The synthesis of α-sialosides is one of the most difficult reactions in carbohydrate chemistry and is considered to be both a thermodynamically and kinetically disfavored process. The use of acetonitrile as a solvent is an effective solution for the α-selective glycosidation of N-acetyl sialic acids. In this report, we report on the α-glycosidation of partially unprotected N-acetyl and N-glycolyl donors in the absence of a nitrile solvent effect.