Synthesis of a tetrasaccharide fragment of mycobacterial arabinogalactan

Article abstract of DOI:10.1016/j.carres.2008.01.024

The arabinogalactan of mycobacteria contains both monosaccharides in the furanose ring form, which are absent in mammals. We report here the first synthesis of the tetrasaccharide fragment α-d-Araf-(1→5)-β-d-Galf-(1→5)-β-d-Galf-(1→6)-d-Galf, conveniently derivatized for further elongation. The strategy relied on the use of suitably substituted d-galactono-1,4-lactones as precursors for the galactofuranose units. Reduction of lactone tetrasaccharide 9 with disiamylborane afforded the tetrasaccharide synthon 1. The tetrasaccharide contains the linker unit of the arabinan to the galactan.