Interfacial supramolecular biomimetic epoxidation catalysed by cyclic dipeptides

Abstract

We synthesised a library of cis- and trans-cyclic dipeptides and evaluated their efficacy as catalysts in the asymmetric Weitz-Scheffer epoxidation of trans-chalcone. A thorough investigation relying on structure-activity studies and computational studies provided insights into the mechanism of the process. Our results revealed some structural features required for efficient conversion and for introduction of chirality into the product. The cyclic dipeptide acts as a catalyst by templating a supramolecular arrangement at the aqueous-organic interface required for efficient transformations to occur. Among all cyclic dipeptides investigated, cyclo(Leu-Leu) was the most efficient supramolecular catalyst.

Keywords:

• Cyclic dipeptides
• interfacial epoxidation
• supramolecular catalysis

Acknowledgements

The authors thank François Otis for his technical assistance with liquid chromatography and in peptide synthesis. This work was supported by the NSERC of Canada, the FQRNT of Quebec, PROTEO and Université Laval. C.B. is also indebted to FRQNT for a postgraduate scholarship.