Synthesis of the tetrasaccharide side chain of the major glycoprotein of the Bacillus anthracis exosporium

An α-glycoside of the tetrasaccharide sequence β-Ant-(1 → 3)-α-l-Rhap-(1 → 3)-α-l-Rhap-(1 → 2)-α-l-Rhap whose aglycon allows conjugation to suitable carriers was synthesized. The NMR characteristics of the compound are virtually identical with those of the α-anomer of the tetrasaccharide isolated from the major glycoprotein of the Bacillus anthracis exosporium. Thus, the correct structure of the natural product has been proven by chemical synthesis.