High Yielding and Practical Synthesis of Rotaxanes by Acylative End-Capping Catalyzed by Tributylphosphine

A pseudorotaxane was prepared from dibenzo-24-crown-8 and a dibenzylammonium salt possessing dimethylphenyl and hydroxy groups at the both termini. Acylation of the pseudorotaxane by 3,5-dimethylbenzoic anhydride in the presence of tributylphosphine afforded corresponding rotaxane in 90% yield. Various rotaxanes were readily synthesized in excellent yields by this method.