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An efficient oxidation of iodoarenes to the corresponding iodylarenes is achieved without the need for any catalyst.

A mild catalytic procedure for the efficient oxidative cyclization of aldoximes with maleimides mediated by hypervalent iodine(III) active species has been developed. This catalytic cyclization affords the corresponding pyrrolo-isoxazole products in generally good yields. The catalytic cycle involves active hydroxy(aryl)iodonium species generated in situ from 2-iodobenzoic acid as precatalyst and m-chloroperoxybenzoic acid (m-CPBA) as terminal oxidant in the presence of trifluoromethanesulfonic acid. The presence of active hydroxy(aryl)iodonium species in this reaction has been confirmed by ESI-mass spectrometry and 1H NMR spectroscopy.

Hypervalent iodine compounds have found wide practical application as versatile, efficient, and sustainable reagents for organic synthesis. Pseudocyclic hypervalent iodine derivatives are characterized by the presence of additional intramolecular non-covalent coordination at the iodine center, which leads to significant alteration of their physical and chemical properties. In comparison with common hypervalent iodine reagents, these pseudocyclic compounds have higher thermal stability, better solubility, and improved reactivity. In recent years, pseudocyclic hypervalent iodine reagents are increasingly used in organic synthesis as environmentally friendly selective oxidants and electrophiles. Furthermore, numerous enantioselective reactions mediated by chiral pseudocyclic hypervalent iodine species have been recently developed. In the present review, the preparation and structural features of pseudocyclic iodine(III) and iodine(V) derivatives are discussed, and recent developments in their synthetic applications are summarized.

The preparation, structure, and chemistry of hypervalent iodine compounds are reviewed with emphasis on their synthetic application. Compounds of iodine possess reactivity similar to that of transition metals, but have the advantage of environmental sustainability and efficient utilization of natural resources. These compounds are widely used in organic synthesis as selective oxidants and environmentally friendly reagents. Synthetic uses of hypervalent iodine reagents in halogenation reactions, various oxidations, rearrangements, aminations, C–C bond-forming reactions, and transition metal-catalyzed reactions are summarized and discussed. Recent discovery of hypervalent catalytic systems and recyclable reagents, and the development of new enantioselective reactions using chiral hypervalent iodine compounds represent a particularly important achievement in the field of hypervalent iodine chemistry. One of the goals of this Review is to attract the attention of the scientific community as to the benefits of...

The process succeeds using various aryl and alkyl aldehydes, and the products are isolated in moderate yields as the corresponding methyl carbamates obtained via Curtius-rearrangement.

Three new saccharin-based hypervalent iodine compounds and a dinuclear analogue are prepared.

The title reaction is promoted by BF3 nitrile complexes and proceeds in moderate to good yields with high regioselectivities.

Hypervalent iodine reagents have found wide application in organic synthesis as versatile, efficient, and environmentally sustainable reagents. Particularly important hypervalent iodine reagents used as atom and group transfer reagents include: iodosylbenzene, (PhIO)n, (tosylimino)iodobenzene, (PhINTs)n, and iodonium ylide, PhI = C(CO2CH3)2. Despite the significant interest in these reagents as primary sources of “O”, “NR” and “CR2” units in transition metal catalyzed processes, their practical application is hampered. In particular, their tightly aggregated and polymeric structures in the solid state render these polyvalent iodine species insoluble in all nonreactive media and prevent their use in chemical reactions under homogenous conditions, which can be undesirable for many synthetic and mechanistic studies. In this review we describe our work on the rational design and development of new soluble, thermally stable, and highly reactive hypervalent iodine reagents based on structural modifications that lead to redirection of secondary bonding from intermolecular to intramolecular modes. Specifically, the introduction of a coordinating donor in the ortho-position of the phenyliodine (III) moiety leads to a significant improvement of solubility of a hypervalent iodine reagent. Based on this approach, we have developed a series of new hypervalent iodine reagents, which can be used as selective oxidants, nitrene or carbene precursors, and atom transfer reagents. Specific examples of these new reagents are represented by iodosylarenes and iminophenyliodanes bearing tert-butylsulfonyl group in the ortho-position of the phenyl ring and by the ortho-alkoxy substituted iodonium imides and ylides. These new pseudocyclic (and cyclic) reagents have excellent solubility in organic solvents and can be used as efficient reagents for catalytic formation of new C O, C N and C C bonds, as well as to enable the generation and detection of highly reactive metal species involved in catalysis and biomimetic reactions.

Hypoiodite species are generated from catalytic amounts of iodine and the terminal oxidant tBuOOH.

1,2,4-Thiadiazoles were efficiently synthesized in good yields through the oxidative dimerization of carbothioamides by using Oxone as a readily available, inexpensive, and environmentally safe oxidant. A similar reaction of phenylselenoamide led to the corresponding 1,2,4-phenylselenadiazole in high yield.

An efficient, transition metal-free procedure for the cyclopropanation of alkenes using malononitrile and the LiI-tBuOCl combination under mild reaction conditions is described. The reaction mechanism most likely involves tBuOI generated in situ from LiI and tBuOCl. The utility of this new methodology has been demonstrated by the synthesis of a potential HIV-1 RT inhibitor.

New hypervalent iodine(V) oxidants are prepared by the reaction of IBX with sulfonic acids.

Hypervalent iodine catalyzed oxidation of aldoximes using oxone as a terminal oxidant generates nitrile oxides, which react with alkenes and alkynes to give the corresponding isoxazolines and isoxazoles in moderate to good yields. This reaction involves active hypervalent iodine species formed in situ from catalytic iodoarene and oxone in the presence of hexafluoroisopropanol in aqueous methanol solution.

Isoxazolines can be efficiently synthesized in good yields via a hypoiodite mediated catalytic oxidative cyclization of aldoximes and alkenes. This reaction involves active iodine species generated in situ from catalytic amounts of KI and Oxone.

Hofmann rearrangement of carboxamides to carbamates using Oxone as an oxidant can be efficiently catalyzed by iodobenzene. This reaction involves hypervalent iodine species generated in situ from catalytic amount of PhI and Oxone in the presence of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) in aqueous methanol solutions. Under these conditions, Hofmann rearrangement of various carboxamides affords corresponding carbamates in high yields.

A thermally stable and water-soluble hypervalent iodine oxidant for oxidative iodination of aromatic substrates is synthesized.

For the first time the title reaction is presented by using the compound (II) as the nitrenium precursor and common inexpensive reagents.

The synthesis of new iodonium ylides derived from dimedone and bearing an ortho-substituent in the phenyl ring is described.

TEMPO derivatives (I) and (II) are synthesized and successfully tested as recycable catalysts for the peracid oxidation of a broad spectrum of primary and secondary alcohols to the corresponding carbonyl compounds.

A new, mild, and efficient method to prepare various methyl carbamates as well as other alkyl carbamates is reported.

Novel, efficient, and recyclable bifunctional catalysts bearing SiO2-supported RuCl3 and iodoarene moieties were developed and used for environmentally benign oxidation of alcohols or alkylarenes at the benzylic position. These reactions in the presence of oxone as stoichiometric oxidant afforded the corresponding carbonyl compounds in high yields under mild conditions and convenient work-up. Furthermore, these SiO2-supported bifunctional catalysts can be recovered by simple filtration and directly reused.

This review summarizes the chemistry of iodonium salts with emphasis of their synthetic applications. The preparation and reactions of diaryliodonium, alkenyl(aryl)iodonium, alkynyl(aryl)iodonium, and alkyl(aryl)iodonium salts are overviewed. Application of these reagents allows mild and highly selective arylations, alkenylations, alkynylations, and alkylations of various organic and inorganic substrates in a facile and environmentally friendly manner.

A facile preparation of novel polystyrene-supported iodosylbenzene (PS-TSB, loading of IO up to 1.50 mmol/g) from iodopolystyrene is described. This resin has been successfully used for efficient oxidation of a diverse collection of alcohols to aldehydes and ketones in the presence of BF 3 ·OEt 2 . PS-ISB can also be employed as efficient co-catalyst in combination with RuCl 3 in the catalytic oxidation of alcohols and aromatic hydrocarbons, respectively, to corresponding carboxylic acids and ketones using Oxone as the stoichiometric oxidant.

The reagent is found to be convenient for the chlorination of alkenes, carbonyl compounds and electron-rich arenes.

Organohypervalent iodine reagents have attracted significant recent interest as versatile and environmentally benign oxidants with numerous applications in organic synthesis. This Perspective summarizes synthetic applications of hypervalent iodine(V) reagents: 2-iodoxybenzoic acid (IBX), Dess−Martin periodinane (DMP), pseudocyclic iodylarenes, and their recyclable polymer-supported analogues. Recent advances in the development of new catalytic systems based on the generation of hypervalent iodine species in situ are also overviewed.

Aromatic hydrocarbons are efficiently oxidized to the corresponding quinones under mild conditions.

A new polymer-supported hypervalent iodine reagent, polystyrene-supported iodosylbenzene sulfate (PS-IBS), can be conveniently prepared by the reaction of polystyrene-supported (diacetoxyiodo)benzene (PS-DIB) with sodium bisulfate monohydrate under solvent-free conditions. This new recyclable reagent effects clean and efficient oxidation of a wide range of alcohols and sulfides to the corresponding carbonyl compounds or sulfoxides in high conversions under mild conditions. The final products are conveniently separated from the polymeric byproduct by simple filtration and isolated in good purity after evaporation of solvent. Recycling of the resin is possible with minimal loss of activity after several reoxidations.

The hypervalent iodine oxidant, consisting of m-iodosylbenzoic acid and iodine, iodinates various enolizable ketones and β-dicarbonyl compounds under mild conditions providing the corresponding α-iodo-substituted carbonyl compounds in good to excellent yields.

Carboxamides (I) react with in situ generated iodine(III) species and methanol to give carbamates (III) via Hofmann rearrangement.

A convenient experimental procedure for the preparation of iodylarenes via RuCl3-catalyzed oxidation of iodoarenes with Oxone is developed.

Recent advances in the development of polymer-supported iodine(V) oxidants, recyclable monomeric hypervalent iodine(III) reagents and catalytic systems based on hypervalent iodine compounds are discussed. These efficient and environmentally friendly reagents and catalysts are particularly useful for oxidative transformations of alcohols to carbonyl compounds and for oxidations at the benzylic position.

Reactions of fluoroxenonium triflate (1), fluorosulfate (2), and nitrate (3), prepared from XeF 2 and the corresponding acids in CH 2 Cl 2 at −50°C, with cyclohexene and 1-hexene result in β-fluoroalkyl triflates, fluorosulfates, and nitrates. Triflate 1 reacts with cyclohexene with exclusive formation of the cis isomer 5, the analogous reactions of fluorosulfate 2 and nitrate 3 give mixtures of the corresponding cis and trans isomers. Reactions of 1-hexene with reagents 1−3 lead to mixtures of two regioisomers with domination of the Markovnikow type of addition. The stereochemical result of these reactions is rationalized in terms of an electrophilic attack by the positive xenonium ion on the π-electrons of the double bond with intermediate formation of organoxenonium species in analogy with the behavior of the isoelectronic iodine(III) species

Allene 1 reacts with PhIO/BF 3 .Et 2 O or PhIF 2 /BF 3 .Et 2 O in CH 2 Cl 2 at -60 o C with the formation of novel phenyldihydrofuryliodonium salts 2. Molecular structures for both products 2a,b are determined by X-ray analysis. Iodonium perchlorate 2b reacts with the anionic nucleophiles (NaN 3 , NaOCH 3 , NaOC 2 H 5 , CuI/KI) to give the corresponding products of the vinylic nucleophilic substitution (6a-e) of the iodobenzene moiety

(Dicyano)iodonium triflate (NC)2I+−OTf can be prepared by the reaction of O=I-OTf with cyanotrimethylsilane and isolated as an air sensitive crystalline solid unstable at room temperature. This compound generated in situ reacts with tributyltin derivatives of various aromatic compounds or acetylenes at −40 °C forming the corresponding iodonium salts in good yield.

Lithium alkynolates (R-CCOLi, R = CH3, n- C4H9, t-C4H9, Ph), generated in situ from dibromomethylketones and a strong base, react with electrophiles (diethyl chlorophosphate or benzoyl chloride) with the formation of the corresponding ynol esters.