Synthesis of 2,3-dihydro-1H-[1]benzothieno[2,3-c]pyrroles and related aminomethylbenzo[b]thiophens

Abstract

Condensation of 5-bromo- or 5-chloro-2-chloromethylbenzo[b]thiophen with dimethylamine, diethylamine, pyrrolidine, piperidine, or morpholine in boiling benzene gave the corresponding 2-aminomethylbenzo[b]thiophen derivatives. 5-Bromo- and 5-chloro-2,3-dimethylbenzo[b]thiophen were prepared and treated with N-bromosuccinimide in boiling carbon tetrachloride to give the corresponding 2,3-bisbromomethyl compounds. Condensation of a bisbromomethyl compound with a primary amine in boiling benzene gave the corresponding bisalkylaminomethyl compound or the 2-alkyl-2,3-dihydro-1H-[1]-benzothieno[2,3-c]pyrrole or a mixture of these two products. Condensation of the bisbromomethyl compounds with secondary amines gave the corresponding cyclic quaternary salts.