Concise and Effective Synthesis of 1→2 α‐Linked Mannopyranosyl Oligosaccharides and Related Antigenic Factor 34 and Dominant of Antigenic Factor 13

A highly concise and effective synthesis of 1 → 2 α‐linked mannopyranosyl oligosaccharides was achieved via TMSOTf promoted condensation of the corresponding benzoylated monosaccharide alkyl orthoester. 1→2 α‐Linked mannosyl di, trisaccharide, antigenic factor 34, and dominant of antigenic factor 13 were readily synthesized by the new method.