Diversity-Oriented Synthesis of a Molecular Library of Immunomodulatory α-Galactosylceramides with Fluorous-Tag-Assisted Purification and Evaluation of Their Bioactivities in Regard to IL-2 Secretion.

Structural variants of α-galactosylceramide (α-GalCer) that stimulate invariant natural killer T (iNKT) cells constitute an emerging class of immunomodulatory agents in development for numerous biological applications. Variations in lipid chain length and/or fatty acids in these glycoceramides selectively trigger specific pro-inflammatory responses. Studies that would link a specific function to a structurally distinct α-GalCer rely heavily on the availability of homogeneous and pure materials.

Removal of acid-labile protecting groups on carbohydrates using water-tolerant and recoverable vanadyl triflate catalyst.

Acetal, trityl, and TBDMS protecting groups on saccharides were subjected to alcoholysis using a catalytic amount of vanadyl triflate in an MeOH-CH2Cl2 solvent system. The configuration at the anomeric positions of saccharides was retained, and no glycosidic bond cleavage and oxidation of sulfides were observed. The presented method was easily implemented, compatible with diverse functional groups, and regioselective in some cases.