Method for the preparation of 4-aryl-3-pyrrolin-2-ones and their 5-bromo derivatives

An effective method for the conversion of 1-acetyl-4-phenyl-2-pyrrolidone into 1-acetyl-4-phenyl-3-pyrrolin-2-one by bromination–dehydrobromination with N -bromosuccinimide, catalyzed by azo-bisisobutyronitrile or by UV irradiation is developed. The method was extended to the 1-acetyl-4-phenyl-3-pyrrolin-2-one structural analogs. An employment of an excess of N -bromosuccinimide under given reaction conditions leads to the bromination of 1-acetyl-4-phenyl-3-pyrrolin-2-one and its structural analogs at position 5.