A NEW STRATEGY FOR OLIGOSACCHARIDE ASSEMBLY EXPLOITING CYCLOHEXANE-1,2-DIACETAL METHODOLOGY - AN EFFICIENT SYNTHESIS OF A HIGH-MANNOSE TYPENONASACCHARIDE

The high-mannose nonasaccharide 1 is part of the glycoprotein gp 120 o f the viral coat of HIV-1. The mannan portion of this triantennary gly can was prepared by a number of consecutive glycosidation steps withou t the need for any protecting-group manipulation. This was achieved by carefully tuning the reactivity of the glycosyl donors by employing o ur cyclohexane-1,2-diacetal (CDA) methodology. The method was further extended with one-pot procedures for oligosaccharide synthesis, thus r educing the number of steps to form the protected nonasaccharide 21 fr om the monosaccharide building blocks to five.