Azole Functionalization: Advances with Diaryliodonium Salts

Abstract The widespread utilization of diaryliodonium salts offers promising and effective approaches toward C─H functionalization or heteroatom arylation of heterocycles, presenting an alternative to traditional arylation methods. The application of diaryliodonium salts under mild conditions is particularly appealing to synthetic chemists, facilitating the incorporation of this reagent into various organic frameworks, including numerous heterocycles. Many remarkable arylation methods using diaryliodonium salts have been successfully employed in the synthesis of natural products and pharma‐relevant compounds. Azoles, characterized by their five‐membered heterocyclic cores are recognized for their significant biological activities, which are explored tremendously with diaryliodonium salts to develop aryl‐containing azole analogues. While N‐arylation of azoles with iodonium salts can be achieved under operationally simple conditions, diaryliodonium salts also enable C‐arylation under comparatively simpler conditions than those associated with traditional arylating sources. This review comprehensively outlines the known methods for the arylation of azoles using both symmetrical and auxiliary‐based iodonium salts. In addition to elucidating the rationale behind the reported methodologies, this review also emphasizes the mechanistic aspects of the arylation processes involving diaryliodonium salts.