Pharmacologically active benzo[b]thiophen derivatives. Part V. 3-(N-alkyl-N-2-chloroethylaminomethyl)-5- or 7-halogenobenzo[b]thiophen hydrochlorides

Abstract

5-Fluoro-, 5-chloro-, 5-bromo-, 7-chloro-, and 7-bromo-3-methylbenzo[b]thiophen have been prepared by cyclisation of the appropriate (halogenophenylthio)acetone with hot polyphosphoric acid. 5-Iodo-3-methylbenzo[b]thiophen could not be prepared in this way but was obtained from 5-amino-3-methylbenzo[b]thiophen via the diazonium salt in the usual way. Bromination of these 5- or 7-halogeno-3-methylbenzo[b]thiophens with N-bromosuccinimide in boiling carbon tetrachloride gave the corresponding 3-bromomethyl derivatives. The 5-halogeno-compounds were condensed with ethanolamine, N-ethyl-, N-isopropyl-, N-t-butyl-, or N-benzylethanolamine, whereas the 7-halogeno-compounds were condensed only with N-ethylethanolamine. The resulting amino-alcohols reacted with thionyl chloride in dry chloroform to give the required 2-chloroethylamines.