Guanidinium-catalyzed addition of pyrrolidine to 2-(5H)-furanone

Bicyclic guanidinium derivatives with different side arms efficiently catalyze the conjugate addition of pyrrolidine to 2-(5H)-furanone, the best results being obtained when the two chains are an aromatic residue and an amine or imidazole, respectively. The catalysis is likely due to the development of strong ion-pairing and hydrogen-bonding in the transition state.