Stereoselective synthesis of 1,2:4,5-di- O-isopropylidene-3- C-(5-phenyl-1,2,4-oxadiazol-3-yl)-β- d-psicopyranose and its X-ray crystallographic analysis

Abstract

In a novel procedure, when 3- O-benzoyl-3- C-( N-hydroxycarbamimidoyl)-1,2:4,5-di- O-isopropylidene-β- d-psicopyranose ( 1) is treated with acetic anhydride, chloroacetyl chloride, propanic anhydride and benzoyl chloride, the 3- O-benzoyl group undergoes an intramolecular replacement reaction with neighbouring group participation and transfer resulting in a more stable conjugated system by the formation of a 1,2,4-oxadiazol ring. A possible mechanism is reported. The structure has been determined by spectroscopic data and X-ray crystallographic analysis.