Topochemical Cycloaddition Reaction between an Azide and an Internal Alkyne

Here we report the synthesis of a trisubstituted-1,2,3-triazole-linked polymer using a topochemical azide-alkyne cycloaddition (TAAC) reaction. A cyclitol-derived monomer having an azide and an internal alkyne group was designed. The four hydroxy groups present in this monomer dictate its crystal packing such that the monomer molecules are arranged head-to-tail, thereby placing the internal alkyne and the azide units of adjacent molecules proximally. Although the alignment of the reactive groups in the monomer crystal is not favourable for a topochemical reaction, a reactive orientation can be achieved by the rotation of the reactive groups. Upon heating the crystals, the monomer underwent topochemical polymerization to yield the trisubstituted-1,2,3-triazole-linked-polycyclitol. This study demonstrates a new synthetic strategy for cycloaddition reaction between non-polarized internal alkynes and azides to yield trisubstituted triazoles.

Automated summary

This study presents a new synthetic strategy for the cycloaddition reaction between non-polarized internal alkynes and azides to yield trisubstituted triazoles. By designing a cyclitol-derived monomer with azide and internal alkyne groups, the reactive orientation necessary for topochemical reaction was achieved through the crystal packing of the monomer molecules. Upon heating, the monomer underwent topochemical polymerization to form a trisubstituted-1,2,3-triazole-linked-polycyclitol.