Pharmacologically active benzo[b]thiophen derivatives. Part VII. Analogues of tryptamine and heteroauxin

Abstract

Some 2-(5-substituted 3-benzo[b]thienyl)ethylamines have been prepared by reduction with lithium aluminium hydride and aluminium chloride in dry ether of the corresponding 3-benzo[b]thienylacetonitriles. Hydrolysis of these cyanides with a mixture of concentrated sulphuric acid, glacial acetic acid, and water (1 : 1 : 1 v/v) gave the corresponding 3-benzo[b]thienylacetic acid derivatives, which reacted with thionyl chloride to give the corresponding acid chlorides. Treatment of the 5-chloro-compound with t-butyl alcohol gave the t-butyl ester, and of all the acid chlorides with methylamine or dimethylamine gave the corresponding secondary or tertiary amides, which were reduced with lithium aluminium hydride and aluminium chloride in dry ether to the corresponding N-methyl-or NN-dimethyl-tryptamine analogues. 3-Benzo[b]thienylmethylamine, 2-(3-benzo[b]thienyl)ethylamine, and their 5-chloro-derivatives reacted with aqueous potassium cyanate to give the corresponding substituted ureas, and with S-methylthiouronium iodide to give the corresponding substituted guanidine hydroiodides. A similar series of compounds with the side-chain in the 2-position of 5-chloro- and 5-bromobenzo[b]thiophen, has been prepared. Some pharmacological results are briefly reported.