A Practical Silicon-Free Strategy for Differentiation of Hydroxy Groups in Arabinofuranose Derivatives

Effective differentiation of 3,5-diol system and 2-hydroxy group in arabinofuranose derivatives, which is required for the preparation of building blocks useful for the synthesis of nucleoside analogues and oligosaccharide fragments of mycobacterial arabinogalactan and lipoarabinomannan, was achieved by using 3,5-di-O-benzoyl-1,2-O-benzylidene-β-d-arabinofuranose or 3-O-(chloroacetyl)-β-d-arabinofuranose 1,2,5-orthobenzoate, both readily accessible from inexpensive methyl α-d-arabinofuranoside via the corresponding glycosyl bromides. The use of expensive organosilicon protecting groups is completely avoided in this novel strategy, a feature that makes it amenable to scale-up.