Synthesis of cyclic peptide-based [2]rotaxanes via copper-catalyzed azide–alkyne cycloaddition†

Cyclic peptide-based [2]rotaxanes were synthesized from cyclo(PG)₄ and monocationic ammonium threads via copper-catalyzed azide–alkyne cycloaddition (CuAAC), achieving relatively high yields of up to 36%. Cyclic peptides that do not contain bulky side chains or amino acids that induce the formation of cis-amide bonds were found to be unsuitable for rotaxane synthesis. This innovative synthetic approach advances the development of multifunctional rotaxanes and opens new avenues for their applications in various fields.