Syntheses of glycosylamides as glycolipid analogs

In search of a simple synthetic access to analogs of naturally occurring glycolipids, glycosylamides have been synthesised in a two-step procedure from unprotected sugars, long-chain amines, and fatty acids. The N-glycosylation proceeded stereospecifically yielding crystalline β-glycopyranosylamines. 13C NMR spectroscopy of the glycosylamines in organic solvents revealed partial anomerisation, leading to α-glycosylamines and in part to corresponding N-furanosides. Selective N-acylation of either pure β-glycosylamines or anomeric mixtures thereof with activated fatty acid led to formation of β-glycosylamides exclusively. As evidenced by NMR spectroscopy, the glycosylamides exhibited rotameric isomerism. The glycosylamides were found to be strong stimulators of the specific immune response against antigens.