Potassium Hydroxide/Dimethyl Sulfoxide Superbase‐Promoted Transition Metal‐Free Synthesis of 2‐Substituted Benzothiophenes under Visible Light

Abstract A potassium hydroxide/dimethyl sulfoxide (KOH/DMSO) superbase‐promoted method for the synthesis of 2‐substituted benzothiophenes has been developed via photoinduced intermolecular annulation of 2‐halothioanisoles with terminal alkynes at ambient temperature. The present protocol uses commercially available 2‐halothioanisoles as substrates and visible light as energy force, which offers a wide range of benzothiophenes regioselectively in moderate to good yields. Such a facile and effective transformation will provide an environment‐friendly approach to the synthesis of benzothiophene derivatives. magnified image