Synthesis of the first examples of iminosugar clusters based on cyclopeptoid cores

Cyclic N-propargyl α-peptoids of various sizes were prepared by way of macrocyclizations of linear N-substituted oligoglycines. These compounds were used as molecular platforms to synthesize a series of iminosugar clusters with different valency and alkyl spacer lengths by means of Cu(I)-catalysed azide-alkyne cycloadditions. Evaluation of these compounds as α-mannosidase inhibitors led to significant multivalent effects and further demonstrated the decisive influence of scaffold rigidity on binding affinity enhancements.