The first total synthesis of a highly branched arabinofuranosyl hexasaccharide found at the nonreducing termini of mycobacterial arabinogalactan and lipoarabinomannan.

[reaction--see text] The first total synthesis of the arabinofuranosyl hexasaccharide present at the nonreducing termini of mycobacterial arabinogalactan and lipoarabinomannan is reported. The oligosaccharide was prepared as its methyl glycoside via a route that is both highly efficient and convergent. Addition of two beta-D-arabinofuranosyl residues simultaneously in high yield and with excellent stereocontrol was the key step of the synthesis.