Heteroaryliodonium(III) Salts as Highly Reactive Electrophiles

Abstract

In recent years, the chemistry of heteroaryliodonium(III) salts has undergone significant developments. Heteroaryliodonium(III) salts have been found to be useful synthetic tools for the transfer of heteroaryl groups under metal-catalyzed and metal-free conditions for the preparation of functionalized heteroarene-containing compounds. Synthetic transformations mediated by these heteroaryliodonium(III) salts are classified into two categories: (1) reactions utilizing the high reactivity of the hypervalent iodine(III) species, and (2) reactions based on unique and new reactivities not observed in other types of conventional diaryliodonium salts. The latter feature is of particular interest and so has been intensively investigated in recent decades. This mini-review therefore aims to summarize the recent synthetic applications of heteroaryliodonium(III) salts as highly reactive electrophiles.

Recent Updates on Electrogenerated Hypervalent Iodine Derivatives and Their Applications as Mediators in Organic Electrosynthesis

“…Hypervalent iodine reagents (HIRs) have recently attracted considerable attention in organic synthesis because of their valuable oxidizing abilities, superior leaving group abilities, unique electrophilic properties, and environment-friendly features ( Yoshimura and Zhdankin, 2016 ; Wang and Studer, 2017 ). To date, their synthetic applications have expanded from ligand transfer reactions, oxidative coupling processes, halogenations, oxidative rearrangements, heterocycle synthesis, and numerous other reactions ( Chen et al, 2020 ; Takenaga et al, 2020 ). Furthermore, the applications of chiral HIRs and asymmetric precursors have resulted in many valuable contributions to modern asymmetric synthesis ( Yang et al, 2021 ).…”

“…HIRs are often considered as environmentally benign alternatives to various chemical oxidants, especially the highly toxic heavy-metal oxidizers, i.e., Pb(IV), Hg(II), and Tl(III) reagents ( Yoshimura and Zhdankin, 2016 ; Takenaga et al, 2020 ). Nevertheless, the current common preparation methods of HIRs pose environmental concerns to their widespread application and upscaling ( Liu et al, 2018 ; Elsherbini and Wirth, 2018 ; Frey et al, 2022 ).…”

Recent Advances in Transition-Metal-Free Late-Stage C-H and N-H Arylation of Heteroarenes Using Diaryliodonium Salts

“…In the last decade, recent progress in this area has been achieved including selective C-H and N-H arylations of heteroarenes using non-toxic and easy-to-handle diaryliodonium salts as aromatic electrophiles [ 39 , 40 , 41 , 42 ]. Most of the arylation reactions show high functional group tolerance and involve a symmetric diaryliodonium salt or a non-symmetric bearing an inert coupling auxiliary, also called a “dummy” group, such as TMB (2,4,6-trimethoxyphenyl), Mes (2,4,6-methylphenyl), TRIP (2,4,6-tri iso propylphenyl) or uracil [ 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 ]. This review provides an overview of the recent developments and early examples of arylating heteroarenes under metal-free conditions using acyclic diaryliodonium salts as coupling partners.…”

Diaryliodonium Salt-Based Synthesis of N-Alkoxyindolines and Further Insights into the Ishikawa Indole Synthesis

“…Diaryliodonium salts have emerged as precursors for new bond formation strategies due to their high reactivity, sufficient stability, and low toxicity. − Various reactions are enabled by metal catalysts, − whereas diaryliodonium salts are useful for metal-free carbon–heteroatom bond formation, offering an attractive metal-free alternative to the Buchwald–Hartwig reaction . A variety of reactions using the iodonium salt have been developed for O -arylation with aliphatic alcohols, − carboxylic acids, − and phenols, ,− as well as N -arylation with amines, − amides, − anilines, ,,, and heteroaromatics. − …”