Phenyl migration to thiophene ring in photolysis of 1-phenylbenzo[b]thiophenium salts

Article abstract of DOI:10.1016/S0040-4039(97)01116-7

Photolysis of 1-phenylbenzo[b]thiophenium salts was conducted by use of a Pyrex-filtered high pressure Hg lamp. The major products in most cases were the phenyl-migrated ones, i.e., 2-phenylbenzo[b]thiophenes and 3-phenylbenzo[b]thiophenes, together with the dephenylated benzo[b]thiophenes. This photochemical behavior is quite different from the thermal ones that provide the ring-opened olefins. The selective phenyl migration to the thiophene ring and the absence of the ionic products are characteristic of benzothiophenium systems.