Mycobacterium tuberculosis, the causitive agent of
tuberculosis (TB), possesses a complex cell wall containing
mannose-rich glycophospholids termed
phosphatidylinositol mannosides (PIMs),
lipomannan (LM), and
lipoarabinomannan (
LAM). These glycophospholipids play important roles in cell wall function and host-pathogen interactions. Synthetic PIM/LM/
LAM substructures are useful biochemical tools to delineate and dissect the fine details of
mannose glycophospholipid biosynthesis and their interactions with host cells. We report the efficient synthesis of a series of azidooctyl di- and trimannosides possessing the following
glycan structures: α-Man-1,6-α-Man, α-Man-1,6-α-Man-1,6-α-Man, α-Man-1,2-α-Man-1,6-α-Man and 2,6-di-(α-Man)-α-Man. The synthesis includes the use of non-benzyl protecting groups compatible with the azido group and preparation of the branched
trisaccharide structure 2,6-di-(α-Man)-α-Man through a double glycosylation of a 3,4-butanediacetal-protected
mannoside. The azidooctyl groups of these synthetic
mannans were elaborated to fluorescent
glycoconjugates and squaric
ester derivatives useful for further conjugation studies.