Mechanochemical Solvent-Free Conditions for the Synthesis of Pillar[5]arene-Containing [2]Rotaxanes

Pillar[5]arene-containing [2]rotaxanes have been efficiently prepared under solvent-free conditions. Specifically, solid-to-solid ball-milling of primary or secondary amine reagents with the inclusion complex resulting from the association of dodecanedioyl dichloride and a pillar[5]arene derivative provided the corresponding diamide [2]rotaxanes in good to excellent yields. Importantly, [2]rotaxanes difficult or even impossible to prepare under classical reaction conditions in solution, are now easily obtained.