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

The regiospecific synthesis of 5-bromothiophenethyl thioureas was accomplis hed in four steps with an overall yield of 40-60%. The requisite regioselec tivity for bromination of the thiophene ring was achieved using bromine in acetic acid at low temperatures. The resulting 5-bromothiophenethylamine hy drobromide is an important precursor for the preparation of substituted thi oureas. The X-ray crystal structure demonstrates that the bromine atom is i ndeed located at the 5-position of the thiophene ring. (C) 2001 Elsevier Sc ience Ltd. All rights reserved.