[2]Rotaxane End-Capping Synthesis by Click Michael-Type Addition to the Vinyl Sulfonyl Group

Abstract

Here we report the application of the click Michael-type addition reaction to vinyl sulfone or vinyl sulfonate groups in the synthesis of rotaxanes through the threading-and-capping method. This methodology has proven to be efficient and versatile as it allowed the preparation of rotaxanes using template approaches based on different non-covalent interactions (i.e. donor-acceptor π-π interactions or H bonding) in yields ranging generally 60%−80% and up to 91% thanks to the mild conditions required (room temperature or 0 ºC and a mild base such as Et3N or DMAP). Furthermore, the use of vinyl sulfonate moieties, suitable motifs for coupling-and-decoupling (CAD) chemistry, implies another advantage as it allows the controlled chemical disassembly of the rotaxanes into their components through nucleophilic substitution of the sulfonates resulting from the capping step with a thiol under mild conditions (Cs2CO3 and room temperature).