Halogeno-Substituted 2- and 3-Methylbenzothiophenes: Use of 1H NMR Spectral Analysis and 1H Nuclear Overhauser Effect for Locating the Halogen Substituent

Article abstract of DOI:10.1002/mrc.1260231006

Thirty-seven halogeno-substituted 2- and 3-methyl-(or halogenomethyl)-benzothiophenes, including 17 new compounds, were prepared.The constitution of 14 of these was confirmed by full analysis (LAOCOON) of their 80 MHz 1H NMR spectra and by 1H<1H> NOE measurements.In this way a by-product from the preparation of 4- and 6-bromo-3-bromomethylbenzothiophenes was shown conclusively to be 5-bromo-3-bromomethylbenzothiophene.The 3-substituted benzothiophenes showed greater NOE enhancement factors at H-4 than at H-2 when the 3-methyl or halogenomethyl substituent was irradiated.