Fast, mild, and convenient procedures for iodination and bromination of carbohydrates: reactions of organoboranes with iodine monochloride, sodium iodide, bromine, and bromine chloride

Article abstract of DOI:10.1139/v82-296

5-6-Dideoxy-1,2-O-isopropylidene-3-O-methanesulfonyl-α-D-xylo-hexafuranosene-5 (1), reacts with BH3-THF to form the tris(glycosyl)borane (2) and with dicyclohexylborane to form the dicyclohexylglycosylborane (3).The iodination and bromination of 2 and 3 has been investigated using a variety of electrophiles.Iodination of either 2 or 3 with NaI-Chloramine-T/NaOAc is complete within one minute with high percentage uptake of iodine (70-90 percent) and recovery of the iodinated sugar (4).Bromination of 2 in 15 minutes with NaBr-Chloramine-T permits a high percentage uptake of bromine (75 percent), and bromination of 3 in 15 minutes with Br2/NaOAc gives the brominated sugar (5) with a reasonably good yield (60 percent) with respect to the starting material (1).