Synthesis of QS-21-Based Immunoadjuvants

Three structurally defined QS-21-based immune adjuvant candidates (<b>2a</b>–<b>2c</b>) have been synthesized. Application of the two-stage activation glycosylation approach utilizing allyl glycoside building blocks improved the synthetic accessibility of the new adjuvants. The efficient synthesis and establishment of the stand-alone adjuvanticity of the examined synthetic adjuvant (<b>2b</b>) open the door to the pursuit of a new series of structurally defined QS-saponin-based synthetic adjuvants