Transition metal-free transfer of iodoarenes by organohypervalent iodine compounds

Abstract

Iodoarenes are important precursors used for the synthesis of compounds with C–C and C–heteroatom bonds. They are accessed either by arene iodination or by multistep functional group transformations, for instance, tandem conversion of –NO₂ to –I. Conventional electrophilic iodination suffers from a limited substrate scope, and the formation of undesired regioisomers cannot be avoided either. The use of organohypervalent iodine compounds (OICs) as sources of iodoarenes in transition metal-free reactions offers a sustainable approach to transfer the iodoaryl motif in tandem with oxidative transformations, wherein the iodine handle can be utilized for further derivatization. This strategy has been successfully employed to obtain many medicinally important compounds such as the antifungal agent broussin, the anticancer compound homo-Crisnatol, the T-type channel inhibitor NMP-7, the anti-tuberculosis agent DB07971, etc. These OIC-based oxidative transformations involving iodoaryl transfers are regioselective, and electron-deficient iodoaryl motifs containing functional groups such as CN, NO₂, CF₃, SO₂CF₃, F, and CO₂Me can be readily integrated, making this protocol applicable for the iodoarylation of propargyl derivatives, allyl systems, β-ketoesters and α-cyanoketones, N,N-diarylation (aryl and iodoaryl) of amines, etc. Furthermore, iodine-substituted diaryl sulfides, diaryl ethers, and propargylic esters can be successfully synthesized using OICs as precursors of iodoarenes. Given these unprecedented advantages of OICs as sources of iodoarenes and reagents for oxidative transformations, this perspective highlights recent developments in the field, primarily from 2019 onwards, focusing on transition metal-free oxidative protocols, mechanistic studies, and synthetic applications.