Convenient synthesis of polybrominated imidazole building blocks

Abstract

The synthesis of the hitherto unknown 1-phenylamino-4,5-dimethylimidazole derivatives 3, 4 and 5 is shown and a bromination study is described by using N-bromosuccinimide. It is extremely remarkable that under mild but nevertheless free radical reaction conditions, even by using drastically increasing amounts of NBS (up to 8 eq.) the bromination provides regioselectively in very good yields only the corresponding 2-bromoimidazoles, whereas no side chain bromination to the 4- and 5-methyl groups is observed. However, under more drastic reaction conditions, reflux in CCl4, polybromination takes place and polybrominated imidazole building blocks are formed in good yields. ©ARKAT USA, Inc.