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; and are accessed either by arene iodination or by multistep functional group transformations, for instance, by tandem conversion of -NO2 to -I. The substrate scope limits the conventional electrophilic iodination, and the formation of undesired regioisomers can not be avoided either. The applications of organohypervalent iodine compounds (OICs) as a source of iodoarene in a transition metal-free fashion, offer a sustainable approach to transfer the iodoaryl motif in tandem with oxidative transformation, whereby the iodine handle can be utilized for further derivatization; and were successfully employed to obtain many medicinally important compounds such as antifungal Broussin, anticancer homo-Cristanol, T-type channel inhibitor NMP-7, anti-tuberoculosis DB07971, etc. These OICs-based oxidative transformations with iodoayl transfers are regioselective, and electron-deficient iodoaryl motif containing functional groups like CN, NO2, CF3, SO2CF3, F, CO2Me, etc., can be frequently integrated, making this protocol feasible for iodoarylation of propargyl derivatives, allyl systems, β-ketoesters, α-cycnoketones, N,N-diarylation (aryl and iodoaryl) of amines, etc. Furthermore, iodine-substituted diaryl sulfides, diaryl ethers, and propargylic esters can be successfully synthesized using these as a precursor of iodoarenes. Given these unprecedented advantages of OICs as a source of iodoarenes and reagents for oxidative transformations, this perspective is dedicated to recent developments in the area, primarily from 2019 onwards, focusing on the transition metal-free oxidative protocols, mechanistic studies, and synthetic applications.