Synthesis of a β1,2-Mannopyranosyl Tetrasaccharide Found in the Phosphomannan Antigen of Candida albicans

The synthesis of a portion of the challenging beta1,2-mannosyl polymer found in the cell walls of Candida albicans was undertaken to develop a conjugate vaccine against C. albicans and to facilitate NMR conformational studies of this unique polysaccharide. The novel approach to the synthesis of tetrasaccharide 1 employed the modified ulosyl bromide 11 as the glycosyl donor which provided high diastereoselectivity. A participating solvent as well as p-chlorobenzyl protection facilitated the new approach.