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Trimethoxyphenyliodonium(III) acetate [TMP-iodonium(III) acetate] functions as an efficient arylation reagent for N,O-protected hydroxylamines, generating aniline derivatives in the absence of transition metal catalysts. Various N-methoxysulfonamides participated in the amination reaction to produce the corresponding N-methoxysulfonylanilines. This amination reaction was compatible with several protecting groups, including Troc (2,2,2-trichloroethoxycarbonyl), Cbz (benzyloxycarbonyl), Boc (tert-butoxycarbonyl), benzyl, acetyl, and silyl groups. This method uses TMP-iodonium(III) acetate and efficiently synthesizes various aniline derivatives that are versatile synthetic intermediates for functional organic molecules.

Hypervalent iodine (HVI) reagents have gained much attention as versatile oxidants because of their low toxicity, mild reactivity, easy handling, and availability. Despite their unique reactivity and other advantageous properties, stoichiometric HVI reagents are associated with the disadvantage of generating non-recyclable iodoarenes as waste/co-products. To overcome these drawbacks, the syntheses and utilization of various recyclable hypervalent iodine reagents have been established in recent years. This review summarizes the development of various recyclable non-polymeric, polymer-supported, ionic-liquid-supported, and metal–organic framework (MOF)-hybridized HVI reagents.1 Introduction2 Polymer-Supported Hypervalent Iodine Reagents2.1 Polymer-Supported Hypervalent Iodine(III) Reagents2.2 Polymer-Supported Hypervalent Iodine(V) Reagents3 Non-Polymeric Recyclable Hypervalent Iodine Reagents3.1 Non-Polymeric Recyclable Hypervalent Iodine(III) Reagents3.2 Recyclable Non-Polymeric Hypervalent Iodine(V) Reagents3.3 Fluorous Hypervalent Iodine Reagents4 Ionic-Liquid/Ion-Supported Hypervalent Iodine Reagents5 Metal–Organic Framework (MOF)-Hybridized Hypervalent Iodine Reagents6 Conclusion

Oxidative coupling strategies that can directly convert the C–H group for chemical transformations are, in theory, ideal synthetic methods to reduce the number of synthetic steps and byproduct generation. Hypervalent iodine reagents have now become one of the most promising tools in developing oxidative couplings due to their unique reactivities that are replacing metal oxidants. As part of our continuous development of oxidative coupling reactions, we describe in this report highly efficient μ-oxo hypervalent iodine catalysts for the direct oxidative coupling of N-methoxyamides and related compounds with aromatic hydrocarbons. The excellent TONs, up to over 100 times, with a best catalyst loading of 0.5 mol% were determined for the oxidative C–H/N–H coupling method, which can provide the most straightforward route to obtaining these unique arylamide compounds.

We have found that in aqueous oxidations the μ-oxo-bridged hypervalent iodine trifluoroacetate reagent 1 {[(PhI(OCOCF3)]2O} is generally more reactive than the corresponding monomeric reagent, especially toward phenolic substrates. μ-Oxo-bridged 1 in aqueous media thus provided dearomatized quinones 3 in excellent yields in most cases compared to conventional phenyliodine(III) diacetate and bis(trifluoroacetate), as a result of the rapid oxidation of both phenols and naphthols 2. Furthermore, the oxidation reactions proceeded even in water using water-soluble μ-oxo oxidant 1, which has promise for μ-oxo-bridged reagent 1 to become the favored reagent over hydrophobic phenyliodine(III) diacetate and bis(trifluoroacetate).

A series of electron-rich bipyrroles were prepared by the regioselective, phenyliodine(III) bis(trifluoroacetate) (PIFA) induced oxidative coupling of pyrroles in the presence of bromotrimethylsilane. Using pyrrole and 3,4-disubstituted pyrroles gave exclusively 2,2′-linked bipyrroles without the formation of other bipyrrole regioisomers. The 3-alkyl- or 3-aryl-substituted pyrroles gave unsymmetrical H-T dimers in high yields as the major isolable α-linked bipyrrole products over the symmetrical H-H dimers. The nature of the N-substituent significantly influences the regioselectivity of the reaction, thus regiocontrolled bipyrrole coupling of N-phenyl- and N-benzyl-substituted pyrroles gave 2,3′-bipyrroles.