Chiral Ureas and Thioureas Supported on Polystyrene for Enantioselective Aza-Henry Reaction in Solvent-free conditions

Abstract

Novel bifunctional ureas and thioureas inmovilized on sulfonylpystyrene have been prepared as recoverable and reusable organocatalysts and used in the stereoselective aza-Henry reaction under solvent-free conditions. The activity and stereoselection of the catalysts are dependent on the length of the tether bringing the active site and the polymer, being the catalyst derived from 1,6-hexane diamine the best one. It has been also demonstrated that the supported catalysts are more effective than the homologous soluble catalysts.