Synthesis of a chiral artificial receptor with catalytic activity in Michael additions and its chiral resolution by a new methodology

Org Biomol Chem. 2010 Apr 21;8(8):1763-8. doi: 10.1039/b925367j.

Abstract

Xanthone derivatives were tested as organocatalysts for the Michael addition of pyrrolidine to an alpha,beta-unsaturated lactam. The receptors combine a double H-bond donor pattern that resembles the oxyanion hole in natural enzymes, with a sulfone or sulfoxide that acts as a proton-transfer group. Since these compounds cannot be obtained enantiomerically pure from natural sources, chiral resolution was necessary to study their enantioselectivity. For the most promising receptor, this was accomplished using a new methodology that exploits its supramolecular interactions with a chiral guest and that is inspired in dynamic combinatorial chemistry. The success in the resolution of the racemic mixture indicates that this new method offers an alternative to kinetic resolution.