Glycosylation chemistry promoted by iodine monobromide: Efficient synthesis of glycosyl bromides from thioglycosides, and O-glycosides from 'disarmed' thioglycosides and glycosyl bromides

Iodine monobromide has been found to be an efficient reagent for the conversion of both 'armed' and 'disarmed' thioglycosides (-SMe, -SPr(i), - SPh) into glycosyl bromides. This reagent is compatible with most common protecting groups, and O-glycosidic linkages. The additional potency of I- Br, compared to iodine, as an iodonium ion source also permits the glycosylation of sugar alcohols by 'disarmed' glycosyl bromides and thioglycosides.