Xanthone Receptors as Oxyanion‐Hole Mimics in Artificial Enzymes

Abstract

Abstract Different xanthone‐based receptors ( 2 – 10 ) for lactones and lactams have been prepared, and the feasibility of these compounds to mimic the known enzymatic ‘oxyanion‐hole’ structure is discussed. The self‐association of the receptors was found to pose a serious drawback for complex formation. X‐Ray crystal structures of receptor dimers allowed us to understand the reasons for their self‐association and to improve the design of the catalysts. The catalytic activity of the receptors has been tested towards the nucleophilic addition of pyrrolidine to unsaturated lactones. Since the resulting complexes were very weak in organic solvents, new receptors were developed for lactams, which showed better stabilities, and their catalytic activities were studied.