Synthesis of C-4 and C-7 triazole analogs of zanamivir as multivalent sialic acid containing scaffolds

The relative reactivities of C-4 and C-7 azides derived from zanamivir were compared in cycloaddition reactions with a panel of alkynes. All of the reactions proceeded efficiently with no observable differences between primary and secondary azides. Significant rate differences were observed between several members of the alkyne panel. Most notably, a trialkyne derived from a 1,3,5-triazine core underwent complete reaction within 4 h, whereas an analogous trialkyne with an all carbon aromatic core required 18 h. These results suggest that the triazine core serves as an internal catalyst.