Regiospecific synthesis, X-ray crystal structure and biological activities of 5-bromothiophenethyl thioureas

The regiospecific synthesis of 5-bromothiophenethyl thioureas was accomplished in four steps with an overall yield of 40–60%. The requisite regioselectivity for bromination of the thiophene ring was achieved using bromine in acetic acid at low temperatures. The resulting 5-bromothiophenethylamine hydrobromide is an important precursor for the preparation of substituted thioureas. The X-ray crystal structure demonstrates that the bromine atom is indeed located at the 5-position of the thiophene ring.