Difructose dianhydrides from sucrose and fructo-oligosaccharides and their use as building blocks for the preparation of amphiphiles, liquid crystals, and polymers

Abstract

Controlled selective protonic activation of the fructosyl moiety in sucrose and fructo-oligosaccharides, with pyridinium poly(hydrogen fluoride) at 20°C, yielded either the kinetic product α- d-fructofuranose β- d-fructofuranose 1,2′:2,1′-dianhydride ( 1), or its thermodynamically more stable isomer α- d- fructofuranose β- d-fructopyranose 1,2′:2,l′-dianhydride ( 2), depending on the hydrogen fluoride-pyridine ratio. A similar reaction was performed with 6,6′-dichloro-6,6′-dideoxysucrose, or 6,6′-dideoxy-6,6′-diiodosucrose, using a slightly higher ratio of HF, resulting in the corresponding 6-deoxy-6-halo-α- d-fructofuranose 6′-deoxy-6′- halo-β- d-fructofuranose 1,2′:2,1′-dianhydride derivatives. Both 6,6′-dihalides were converted, upon action of the appropriate nucleophile, into the difructofuranose dianhydride derivatives bearing the 6,6′-di- S-heptyl-6,6′-dithio, 6,6′-diazido-6,6′-dideoxy and then 6,6′-diamino-6,6′-dideoxy functionalities. 6-Chloro-6-deoxy and 6-deoxy-6-iodo derivatives of 2 were also prepared by direct halogenation, and further converted into the 6- S-heptyl-thio, 6-azido-6-deoxy and then 6-amino-6-deoxy derivatives of 2. Reaction of chloromethyloxirane with 1 or 2 yielded hydrophilic polymers. The 6,6′-di- S-heptyl-6,6′-dithio derivative of 1 displayed liquid crystal properties. The 6,6′-dideoxy-6,6′-diiodosucrose precursor was prepared by the reaction of Garegg's iodine-imidazole-triphenylphosphine reagent with sucrose in N,N-dimethylformamide solution.