Regioselective construction of naphtho[2,1-b]thiophenes through iodocyclization of 2-ethynylaryl-3-arylthiophenes

Regioselective iodocyclization of 2-ethynylaryl-3-arylthiophenes was developed for the efficient construction of naphtho[2,1- b ]thiophenes under mild conditions. The present substrate design enabled selective formation of a single naphtho[2,1- b ]thiophene framework. The cyclization was promoted by cooperative electronic effects of the ethynylaryl and nucleophilic aryl moieties, providing the corresponding aryl iodides. The resulting iodides underwent palladium-catalyzed cross-coupling reactions, allowing straightforward synthesis of structurally diverse naphtho[2,1- b ]thiophene scaffolds.