Catalyst-free, direct synthesis of dibenzothiophenes

A catalyst-free method for the synthesis of dibenzothiophenes has been developed. The nucleophilic intramolecular cyclization of methylthiolated diazonium salts enables the direct synthesis of dibenzothiophenes under mild reaction conditions. The addition of TEMPO is beneficial for improving the reaction yield by suppressing the formation of by-products, which can be formed via a radical-mediated process. This simple method provides an alternative for the synthesis of dibenzothiophenes, which are frequently found in valuable compounds.