Synthesis of 2-substituted benzo[b]thiophenes via gold(i)-NHC-catalyzed cyclization of 2-alkynyl thioanisoles.

Benzo[b]thiophene heterocycles are important components of many important small molecule pharmaceuticals and drug candidates as well as organic semiconducting materials. Many methods have been developed for the construction of a benzo[b]thiophene core via cyclization reaction of alkynes. Although few catalytic reactions were disclosed, most methods rely on stoichiometric activation of alkynes.