Synthesis and herbicidal activity of 4-benzylidene-2-phenyl oxazol-5(4H)-one derivatives using l-proline as catalyst

Abstract

A simple, efficient and environmentally benign method for the synthesis of 4-benzylidene-2-phenyl oxazol-5(4H)-one derivatives by the reaction of aromatic aldehydes and hippuric acid using acetic anhydride as dehydrating agent and L-proline as catalyst has been developed. L-proline acts as a highly efficient organocatalyst .It is thermally stable and can withstand harsh reaction conditions besides being easily available and environmentally non-hazardous. The structures of synthesized compounds were evaluated by FT-IR and1H-NMR spectroscopy. The present method is superior to the existing methods as it takes less reaction time, involves easy work up and affords products in excellent yield. The preliminary bioassay of synthesized compounds indicated that most of the compounds exhibited good seed germination inhibition activity against radish seed (Raphanus sativus).