Recent Progress in Cyclic Aryliodonium Chemistry: Syntheses and Applications

Abstract

Hypervalent aryliodoumiums are intensively investigated as arylating agents. They are excellent surrogates to aryl halides, and moreover they exhibit better reactivity, which allows the corresponding arylation reactions to be performed under mild conditions. In the past decades, acyclic aryliodoniums are widely explored as arylation agents. However, the unmet need for acyclic aryliodoniums is the improvement of their notoriously low reaction economy because the coproduced aryl iodides during the arylation are often wasted. Cyclic aryliodoniums have their intrinsic advantage in terms of reaction economy, and they have started to receive considerable attention due to their valuable synthetic applications to initiate cascade reactions, which can enable the construction of complex structures, including polycycles with potential pharmaceutical and functional properties. Here, we are summarizing the recent advances made in the research field of cyclic aryliodoniums, including the nascent design of aryliodonium species and their synthetic applications. First, the general preparation of typical diphenyl iodoniums is described, followed by the construction of heterocyclic iodoniums and monoaryl iodoniums. Then, the initiated arylations coupled with subsequent domino reactions are summarized to construct polycycles. Meanwhile, the advances in cyclic aryliodoniums for building biaryls including axial atropisomers are discussed in a systematic manner. Finally, a very recent advance of cyclic aryliodoniums employed as halogen-bonding organocatalysts is described.

Cyclic Homo- and Heterohalogen Di-λ3-diarylhalonium Structures

“…In fact, the parent diphenylene-iodonium (“DPI”) cation (archetype B ) is widely used as a broad-spectrum go-to inhibitor of NADPH oxidases and other flavoenzymes, either as reporter/modulators of cellular activity or as therapeutic candidates . Recently, the ability of the Lewis acidic iodine­(III) center to engage in highly directional intermolecular interactions, sometimes referred to as “halogen bonding”, has come under a spotlight in the fields of crystal engineering, molecular recognition, and Lewis acid organocatalysts. , Another center of focus has been the revival (after decades of relatively little interest) of the hypervalent derivatives of the lighter two halogens: Br and Cl. , Fresh examples include the bromonium-based cycloaddition reactions from the Wencel–Delord laboratory (Figure , D ), − as well as chiral Br- and Cl-centered onium salts as enantioselective halogen-bonding catalysts by Yoshida et al (structure E )…”

Recent Progress in Synthetic Applications of Cyclic Hypervalent Iodine(III) Reagents

“…The chemistry and numerous synthetic applications of cyclic aryliodonium salts (Figure 1) were very recently summarized in a comprehensive review by Wen, Gu, and co-authors. [7] All other important reagents shown in Figure 1 are derived from the readily available heterocyclic system of benziodoxole. [4] The applications of aryl-, alkynyl-, and alkenylbenziodoxoles as efficient reagents for direct arylation, alkynylation, and alkenylation of various organic substrates were comprehensively reviewed in 2023.…”

Cooperativity between the Silver(I) and Iodine(III) Centers in Electrophilic Activation of Organic Substrates

“…One of the most promising types of these organocatalysts are based on iodonium salts, which effectively catalyze a wide range of organic reactions. [22][23][24][25][26][27][28][29][30][31][32] Despite the advantages of organocatalysts, metal-complex catalysis is still widely used in organic chemistry. Analysis of the current literature data indicates that although today there is a pronounced trend towards the use of metal-complex catalysts based on environmentally friendly and/or biocompatible metal centers, the use of noble group metal centers still occupies a leading position in some areas of application, in particular, selective ortho- 33,34 and meta-functionalization 33,[35][36][37][38][39][40][41] of aromatic compounds and crosscoupling reactions, as well as hydrogenation 42,43 and hydrosilylation 44,45 processes.…”