Asymmetric epoxidation of chalcone catalyzed by reusable poly-l-leucine immobilized on hydrotalcite

Nanohybrid materials based on polyamino acids immobilized onto inorganic materials are of interest for their potential applications in protein engineering, biomedicine and catalysis. We developed an efficient and eco-friendly new protocol for the immobilization of synthesized poly-l-leucine (PLL) onto rehydrated hydrotalcite (HTr). To do this, we synthesized different PLLs containing both C-terminal and N-terminal groups and compared them with a commercial PLLc. These synthetic polypeptides were immobilized onto HTr in water as the liquid medium with less than 30 min of ultrasound treatment. The obtained PLLs/HTr synzyme showed excellent activity and enantioselectivity when used as a catalyst in the asymmetric Julià–Colonna epoxidation reaction of chalcone. Moreover, these nanohybrid materials based on PLLS did not require any pre-activation time, which were easily separated from the reaction media and, unlike the commercial PLLc-supported catalyst, were reusable, exhibiting high stability after five consecutive runs without any apparent deactivation.