Halogeno‐substituted 2‐ and 3‐methylbenzo[b]thiophenes: Use of 1H NMR spectral analysis and 1H{1H} nuclear Overhauser effect for locating the halogen substituent

Thirty‐seven halogeno‐substituted 2‐ and 3‐methyl‐(or halogenomethyl)‐benzo [b]thiophenes, including 17 new compounds, were prepared. The constitution of 14 of these was confirmed by full analysis (LAOCOON) of their 80 MHz1HNMR spectra and by 1H{1H} NOE measurements. In this way a by‐product from the preparation of 4‐ and 6‐bromo‐3‐bromomethylbenzo[b]thiophenes was shown conclusively to be 5‐bromo‐3‐bromomethylbenzo[b]thiophene. The 3‐substituted benzo[b]thiophenes showed greater NOE enhancement factors at H‐4 than at H‐2 when the 3‐methyl or halogenomethyl substituent was irradiated.