An Efficient Synthesis of 2-Ethyl-7-chloro-4-methylthieno[4,3,2-e,f][3]benzazepine (SK&F 106686)viaBromomethylation of 2-Ethyl-5-chlorobenzo[b]thiophene

Abstract The synthesis of 2-ethyl-3-bromoethyl-5-chlorobenzo[b]thiophene (6) is described using a unique phase transfer catalyzed bromoethylation of 2-ethyl-5-chlorobenzo[b]thiophene (5). Compound 6 was converted in six steps and in 55% overall yield to the angiotension II antagonist, SK&F 106686 (1).