Redox-Driven Chiral Inversion of Water-Soluble Pillar[5]arene with l-Cystine Derivative in the Aqueous Medium.

In the aqueous solution, l-CySS-OMe induced pS-WP5 from racemic WP5. Upon the addition of dithiothreitol as a reducing reagent to the above system, pS-WP5 was then converted to pR-WP5 for the reason that l-CySS-OMe was reduced to l-Cys-OMe. Followed by the addition of H2O2 as an oxidation reagent, pR-WP5 was converted back to pS-WP5. The chiral conformational transferring process between pR-WP5 and pS-WP5 can be easily and visually observed by reading the CD signal.