Total Synthesis of an All-1,2--Linked Repeating Unit from the D78 Capsular Polysaccharide.

Chemical synthetic efforts have resulted in the preparation of the assigned tetrasaccharide repeating subunit from the KL4-associated capsular polysaccharide. A convergent synthetic strategy hinging on a 1,2--selective [2+2] glycosylation to generate the fully protected tetrasaccharide was key to the success of this synthesis.