Ring opening of acylated β- d-arabinofuranose 1,2,5-orthobenzoates with nucleophiles allows access to novel selectively-protected arabinofuranose building blocks

β- d-Arabinofuranose 1,2,5-orthobenzoates with 3- O-acetyl, 3- O-benzoyl, and 3- O-chloroacetyl groups were prepared in an efficient manner starting from readily available crystalline methyl 2,3,5-tri- O-benzoyl-α- d-arabinofuranoside, and ring-opening reactions of these compounds with O- and S-nucleophiles were studied. Optimized conditions leading to the formation of the respective monosaccharide adducts (up to 96% isolated yields) and to α-(1→5)-linked disaccharide thioglycosides with 5′-OH unprotected (up to 30% isolated yields) were found. Basing on these results, a novel approach for effective differentiation of 3,5-diol system and 2-hydroxy group in arabinofuranose thioglycosides was proposed. The selectively protected derivatives prepared are valuable building blocks for the assembly of linear and branched oligoarabinofuranosides.