Elaboration of monoarabinofuranosidic building blocks

Nucleophilic opening of 1,2,5-orthoesters 1, 2 and 6 Of D-arabinose with alcohols, ethanethiol and selenophenol was carried out under very mild conditions with Lewis acid catalysis. The reaction is stereoselective and gave alpha-D-arabinofuranosides in high yields. Various monoarabinofuranosides, thio- and selenoglycoside donors as well as acceptors were obtained in few steps from the opening products. These building blocks define a comprehensive system of glycosylation for the synthesis of any glycosidic linkage between arabiriofuranosides.