Direct and efficient conversion of thioamides to benzazole derivatives using N,N'-dibromophenytoin

A novel and efficient method has been developed for preparation of benzoxazole, benzimidazole and benzthioazole via one-pot condensation of N,N'-disubstituted thioamides with 2-aminophenol, 2-aminothiophenol, and 1,2-diaminobenzene using N,N'-dibromo phenytoin as a mild oxidant. Hence, thioamides were reacted with 2-aminophenol, 2-aminothiophenol, and 1,2-diaminobenzene respectively in the presence of N,N'-dibromo phenytoin in DMF to produce benzoxazole, benzimidazole and benzthioazole derivatives in moderate to good yields. Possibility of synthesis of three different heterocycles which have important industrial, agricultural, and biological applications, is one of the advantages of the presented method. Performing the reaction under very mild temperature and in short time is still another merit of the current method.