A highly convergent synthesis of an N-linked glycopeptide presenting the H-type 2 human blood group determinant

The total synthesis of an H-type blood group determinant in a model biological setting is described. The construct is comprised of a high mannose core structure with projecting lactose spacers, culminating in a two-copy presentation of the H-type blood group determinant itself. Key reactions that were used in this construction include sulfonamidohydroxylation (see 15→18) and benzoate-directed glycosylation via an activated thiophenyl donor (see 34→36). Another key strategic element involved the epimerization of an interior core glucoside to reach the β-mannoside (see 37→38) required in the ring C sugar of the high mannose core.