Generation of β-Linked GlcNac and GalNAc Terminating Disaccharide Library through Glycosylation on Unprotected Monosaccharides

Background: The GlcNAc related sulfated disaccharides were reported to show inhibitory activity on breast tumor cells (MDA-MB-231). However, synthesis of sulfated disaccharides is laborious and time consuming, and there is a need to find more efficient methods to generate the sulfated disaccharide libraries in acceptable ratios and in respectable yields. Random glycosylation followed by sulfation may be a good method to synthesize sulfated disaccharide library. However, there is a dearth of simple methods to generate the GalNAc and GlcNAc related disaccharides with acceptable ratio by random glycosylation. Results: Following a generic procedure, random glycosylation of unprotected monosaccharides and followed by deprotection, acetylation, deacetylation, and purification, yielded the GalNAc-GlcNAc disaccharide library containing three β-linked disaccharides with a 1:1:1 ratio and the GlcNAc-Gal disaccharide library containing four β-linked disaccharides with 1:1:2:2 ratio. These results were confirmed by comparison of their proton NMR spectra with that of standard disaccharides. Conclusion: Random glycosylation was employed to generate GalNAc and GlcNAc related disaccharide libraries and was demonstrated as the most efficient method thus far for the synthesis of GalNAc and GlcNAc related disaccharide libraries with excellent ratios, which further can be used as the starting materials for random sulfation to synthesize the sulfated disaccharide libraries.