Microwave-enhanced ionothermal CuAAC for the synthesis of glycoclusters on a calix[4]arene platform

A tetra-azido calix4]arene derivative was allowed to react with ethynyl tetra- O-benzyl- C-galactoside in the presence of CuI and i-Pr 2EtN in three different ionic liquids, that is, C 8dabco]N(CN) 2], C 8dabco]Br], and Ammoeng 110. Reactions were performed at 80 degrees C by thermal and MW dielectric heating. In all cases, multiple cycloadditions took place to give a triazole-linked tetra- C-galactosyl-calix4]arene in up to 90% yield. The C 8dabco]N(CN) 2] ionic liquid was also used to perform the multiclick reactions with propargyl O-lactoside and S-sialoside.