Stereoselective phosphorylation of branched cyclodextrins with inorganic cyclo-triphosphate Original Research Article

The phosphorylation by inorganic sodium cyclo-triphosphate (P3m) having a six-membered ring was examined for cyclomaltohexaose (α-cyclodextrin) and branched cyclodextrins (mono-6-O-α-d-glucopyranosylcyclomaltohexaose, mono-6-O-α-d-maltosylcyclomaltohexaose, mono-6-O-α-d-glucopyranosylcyclomaltoheptaose, and mono-6-O-α-d-maltosylcyclomaltoheptaose) in aqueous solution. For all cyclomaltooligosaccharides (cyclodextrins) studied, the 2-OH group was stereoselectively phosphorylated. In the reaction of branched cyclodextrins and P3m, only the 2-OH on the α-d-glucopyranosyl group of the cyclodextrin rings was phosphorylated with maximum yields of more than 27%. The phosphorylation mechanism of branched cyclodextrins with P3m is also discussed.