Conjugate Addition-Approach to End-Capping of Pseudorotaxanes for Rotaxane Synthesis.

Conjugate addition of 4-tert-butylbenzenethiol to pseudorotaxane having terminal α,β-unsaturated ester group under radical condition afforded the corresponding aryl sulfide-capped rotaxane, while conjugate addition of sodium 4-tert-butylbenzenesulfinate under acidic condition also yielded aryl sulfone-capped rotaxane.