The reactivity of 3-bromo-2-nitrobenzo [b] thiophene (1) with several (anionic and neutral) nucleophiles has been examined. Only with neutral, weak nucleophiles (as anilines) 1 gives, in the presence of non-nucleophilic bases (triethylamine or potassium carbonate), together with the 'expected'3-amino-2-nitrobenzo [b] thiophenes (3) also the 'unexpected'2- amino-3-nitrobenzo [b] thiophenes (4). The composition of the final isomeric mixture ...