Recent Advances in the Synthesis of Dibenzothiophenes

Abstract

Dibenzothiophenes are widely used in organic photoactive compounds, dyes, liquid crystals, conducting polymers, pharmaceuticals and other fields. Until now, various approaches for their synthesis have been well-documented, among which the cyclization of the C-S bond and the C-C bond to achieve the construction of a five-membered sulfur heterocycle in the dibenzothiophene structure is most widely reported. Besides, it also can be realized by the formation of a benzene ring in a dibenzothiophene structure through cyclization of thiophene/its derivatives and a four-carbon synthon. The formation of intramolecular C-S bonds by acids, bases and other non-metallic species is another alternative for dibenzothiophenes synthesis. However, most of these methods are limited by their reliance on prefunctionalization of starting materials or multistep procedures. Over the past decades, transition-metal-catalyzed coupling reactions have emerged as a powerful method for the construction of dibenzothiophenes. In this mini review, based on the latest research progress on dibenzothiophene synthesis until 2020, we briefly discuss the following types of cyclization methods.