Ipso attack in the nitration of 5-bromo- and 5-methyl-2-cyclopropylthiophenes

Article abstract of DOI:10.1007/BF00507242

It was established that 5-bromo-2-cyclopropylthiophene and 5-methyl-2-cyclo-propylthiophene undergo transformations during nitration with nitric acid in acetic anhydride that are a consequence of ipso attack of the nitryl cation in the 2 or 5 positions of the thiophene rings of the starting compounds.