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 beta-glycopyranosylamines. C-13 NMR spectroscopy of the glycosylamines in organic solvents revealed partial anomerisation, leading to alpha-glycosylamines and in part to corresponding N-furanosides. Selective N-acylation of either pure beta-glycosylamines or anomeric mixtures thereof with activated fatty acid led to formation of beta-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. (C) 1998 Elsevier Science Ltd. All rights reserved.