The use of silyl groups in the synthesis of arabinofuranosides

The review considers the known strategies for the synthesis of fragments of arabinogalactan and lipoarabinomannan, polysaccharides that are contained in the cell walls of causative agent of tuberculosis Mycobacterium tuberculosis, as well as other related oligosaccharides containing arabinofuranose residues, using silyl substituents both for the differentiation of hydroxy groups in monosaccharide blocks and as stereodirecting groups during formation of a β-arabinofuranoside bond. In particular, the use of silyl groups (in combination with orthogonal to them acyl groups) allows the stereoselective synthesis of arabinans without the involvement of benzyl groups removable under reducing conditions, which is unacceptable in the presence of fragments sensitive to hydrogenolysis. This significantly simplifies the synthesis of 1,2-cis-linked oligosaccharides containing multiple bonds or azide groups, in particular, in aglycone, which is extremely important for the preparation of neoglycoconjugates both by converting the azide to an amine, followed by covalent binding to a carrier, and by conducting click-chemistry reactions using the 1,3-dipolar cycloaddition of azides to alkynes.