Pharmacologically active benzo[b]thiophen derivatives. Part VI. 4-and 6-Halogeno-derivatives of N-2-chloroethyl-N-ethyl-3-aminomethylbenzo[b]thiophen hydrochloride

Cyclisation of (m-chlorophenylthio)acetone in hot polyphosphoric acid gave a mixture of 4-chloro- and 6-chloro-3-methylbenzo[b]thiophen (7 : 4), and of (m-bromophenylthio)acetone a mixture of 4-bromo- and 6-bromo-3-methylbenzo[b]thiophen (1 : 3). These products were identified by the unambiguous synthesis of both 4- and 6-chloro-3-methylbenzo[b]thiophen, and of 4-bromo-3-methylbenzo[b]thiophen. Bromination of the substituted 3-methylbenzo[b]thiophens with N-bromosuccinimide in boiling carbon tetrachloride gave the corresponding bromomethyl compounds, which reacted readily with 2-ethylaminoethanol in boiling benzene. The resulting amino-alcohols reacted with thionyl chloride in dry boiling chloroform to give the required (2-chloroethyl)amines.