Carbon Tetrachloride-Free Allylic Halogenation-Mediated Glycosylations of Allyl Glycosides

Allylic bromination of allyl glycosides is conducted using NBS/AIBN reagents in (EtO)2CO and PhCF3 solutions, free from CCl4 as a solvent. The activated mixed halo-allyl glycosides lead to glycosylations, mediated by a triflate, in a latent-active manner, with allyl glycosides acting as donors and acceptors. Systematic glycosylation studies are performed with varying triflate promoters, with non-glycosyl acceptors and varied allyl glycosyl donors. One-pot allylic halogenations and subsequent glycosylations are devloped in PhCF3 solutions. The newer glycosylation method is utilized to form xylo-pyranoside di- and trisaccharides.