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Experimental evidence for hypervalent compounds of second‐row elements is still scarce in literature. Here, we present the first report of the long‐sought binary, hypervalent trifluorooxygenate anion [OF3]−. It was isolated in solid Ne matrices under cryogenic conditions after reacting oxygen difluoride with free fluoride ions from laser ablation of alkali metal fluorides MF (M=Li−Cs). VSEPR theory and calculations at the CCSD(T) level predict a C2v‐symmetric T‐shape structure with one short and two long O−F bond lengths in [OF3]−. This is confirmed experimentally by FTIR spectroscopy in combination with isotopic labeling. Analysis of the natural local molecular orbitals shows the presence of one 2c–2e and one 3c–4e bond each. Natural resonance theory indicates the importance of the stability of [OF2]⋅− for the stability of [OF3]−. Although free [OF2]⋅− was not detected, the species MOF2 (M=Na−Cs) could be observed in the same experiments, which are best described as contact ion pairs of M+[OF2]⋅−. [ABSTRACT FROM AUTHOR]

The 2,2‐difluoroethyl group is an important lipophilic hydrogen bond donor in medicinal chemistry, but its incorporation into small molecules is often challenging. Herein, we demonstrate electrophilic 2,2‐difluoroethylation of thiol, amine and alcohol nucleophiles with a hypervalent iodine reagent, (2,2‐difluoro‐ethyl)(aryl)iodonium triflate, via a proposed ligand coupling mechanism. This transformation offers a complementary strategy to existing 2,2‐difluoroethylation methods and allows access to a wide range of 2,2‐difluoroethylated nucleophiles, including the drugs Captopril, Normorphine and Mefloquine. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A new family of dibenzoullazine derivatives was synthesized through 1,3‐dipolar cycloaddition of polycyclic aromatic azomethine ylides with alkynylbenziodoxoles followed by oxidation. The benziodoxole moiety in the resulting products was used as a versatile linchpin for the synthesis of structurally diverse functional dibenzoullazines that are difficult to access by other synthetic methods. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A new family of dibenzoullazine derivatives was synthesized through 1,3‐dipolar cycloaddition of polycyclic aromatic azomethine ylides with alkynylbenziodoxoles followed by oxidation. The benziodoxole moiety in the resulting products was used as a versatile linchpin for the synthesis of structurally diverse functional dibenzoullazines that are difficult to access by other synthetic methods. [ABSTRACT FROM AUTHOR]

The hypercoordinate [SiH6]2− anion is not stable in solution. Here, we report the room temperature, solution stable molecular [SiH6]2− complex, [{KCa(NON)(OEt2)}2][SiH6] (NON=4,5‐bis(2,6‐diisopropylanilido)‐2,7‐di‐tert‐butyl‐9,9‐dimethyl‐xanthene)), where the [SiH6]2− anion is stabilised within a supramolecular assembly that mimics the solid‐state environment of the anion in the lattice of K2SiH6. Solution‐state reactivity of the complex towards carbon monoxide, benzaldehyde, azobenzene and acetonitrile is reported, yielding a range of reduction and C−C coupled products. [ABSTRACT FROM AUTHOR]

Arynes are fleeting, high‐energy intermediates that undergo myriad trapping reactions by nucleophiles. Their unusual reactivity compared to other electrophiles can spur unexpected mechanistic pathways enroute to the formation of benzenoid products. Herein we explore a particularly unique case of thermally generated arynes reacting with phosphoranes to form helical dibenzothiophenes and ‐selenophenes. Multiple new helical polycyclic aromatic products are reported. DP4+ and X‐ray crystallographic analysis were used in tandem to confirm the structural topologies of selected products and to demonstrate the utility of DP4+ for distinguishing between isomeric polycyclic aromatic compounds. Lastly, we discuss a plausible mechanism consistent with DFT computations that accounts for the product formation; namely, ligand coupling (i.e. reductive elimination) within a hypervalent, pentacarbon‐ligated σ‐phosphorane furnishes the dibenzothio‐ or dibenzoselenophene. [ABSTRACT FROM AUTHOR]

Electrochemically generated hypervalent iodine(III) species are powerful reagents for oxidative C−N coupling reactions, providing access to valuable N‐heterocycles. A new electrocatalytic hypervalent iodine(III)‐mediated in‐cell synthesis of 1H‐N‐aryl‐3,4‐dihydroquinolin‐2‐ones by dehydrogenative C−N bond formation is presented. Catalytic amounts of the redox mediator, a low supporting electrolyte concentration and recycling of the solvent used make this method a sustainable alternative to electrochemical ex‐cell or conventional approaches. Furthermore, inexpensive, readily available electrode materials and a simple galvanostatic set‐up are applied. The broad functional group tolerance could be demonstrated by synthesizing 23 examples in yields up to 96 %, with one reaction being performed on a 10‐fold higher scale. Based on the obtained results a sound reaction mechanism could be proposed. [ABSTRACT FROM AUTHOR]

A computational analysis of possible routes of cooperative catalysis involving hydrogen bond donating thiourea and halogen bond donating organocatalysts was carried out. For the model systems involving thiourea and 2-iodoimidazolium or iodonium salt derivatives, the previously suggested route including sequential electrophilic activation of a reaction electrophile via XB-activated HB donor was ruled out. [ABSTRACT FROM AUTHOR]

Hypervalent iodine compounds are described with perfluoroalkyl chains and S‐perfluoromethyl sulfoximines as ligands of the halogen. The influence of these groups on the stability of the cyclic structure is studied. The crucial role of the trifluoromethyl chain is clearly highlighted as an efficient ligand for the hypervalency. The structure and the reactivity of the new skeletons are discussed in detail. [ABSTRACT FROM AUTHOR]

Herein, we report a facile and proficient protocol for the synthesis of 4‐bromoisocoumarins through brominative annulation of 2‐alkynylaryloate esters with in situ generated bromoiodane using a simple hypervalent iodine reagent as mild oxidant and potassium bromide as the halogen source. Using this method, a broad range of valuable halogenated isocoumarins can be obtained in excellent yields at room temperature. Also, this reaction takes place in the absence of any metal catalyst and exhibits high functional group tolerance. Besides, the reaction can also be extended to the gram scale, and a catalytic approach was also demonstrated. Additionally, the prepared 4‐bromoisocoumarins were further transformed into important synthetic compounds. [ABSTRACT FROM AUTHOR]

1,2‐Dioxygenation of alkenes leads to a structural motif ubiquitous in organic synthons, natural products and active pharmaceutical ingredients. Straightforward and green synthesis protocols starting from abundant raw materials are required for facile and sustainable access to these crucial moieties. Especially industrially abundant aliphatic alkenes have proven to be arduous substrates in sustainable 1,2‐dioxygenation methods. Here, we report a highly efficient electrocatalytic diacetoxylation of alkenes under ambient conditions using a simple iodobenzene mediator and acetic acid as both the solvent and an atom‐efficient reactant. This transition metal‐free method is applicable to a wide range of alkenes, even challenging feedstock alkenes such as ethylene and propylene, with a broad functional group tolerance and excellent faradaic efficiencies up to 87 %. In addition, this protocol can be extrapolated to alkenoic acids, resulting in cyclization of the starting materials to valuable lactone derivatives. With aromatic alkenes, a competing mechanism of direct anodic oxidation exists which enables reaction under catalyst‐free conditions. The synthetic method is extensively investigated with cyclic voltammetry. [ABSTRACT FROM AUTHOR]

The diarylation and skeletal diversification of unstrained cyclic amines was exploited to expand and modify the favorable properties of this important substrate class with pivotal roles in drug discovery. Cyclic amines were employed in the synthesis of a novel class of amino‐substituted diaryliodonium salts, which were converted to highly functionalized diarylamines through an atom‐efficient one‐pot N‐arylation/ring opening reaction with external nucleophiles. The reaction proceeds through in situ formation of a diarylammonium intermediate that undergoes a nucleophilic ring opening by cleavage of the strong C−N bond. A wide variety of diarylamines was obtained through introduction of two different aryl groups of varied electronics, and the retained iodo‐substituent enables downfield diversifications of the products. More than 20 nucleophiles, including amines, phenols, carboxylic acids, thiols and halides, were alkylated with high functional group tolerance, and the strategy proved efficient also in in late‐stage functionalization of natural products and pharmaceuticals. [ABSTRACT FROM AUTHOR]

Our group has reported several one‐pot protocols for the synthesis of diaryliodonium salts, which have been recognized as attractive multi‐purpose reagents in areas ranging from organic synthesis to materials chemistry. Over the years, we have identified limitations in the published protocols concerning synthesis of mixed electron‐rich and electron‐poor, as well as highly electron‐poor diaryliodonium salts, as the corresponding starting materials are either too reactive or too unreactive. In this update, we discuss the underlying limitations concerning the stability and reactivity of the involved reagents and provide strategies to overcome these challenges through updated synthetic protocols. [ABSTRACT FROM AUTHOR]

Phosphoranides comprising three phosphorus carbon bonds are scarcely represented in the literature. We now utilized tris(pentafluoroethyl)phosphane, P(C2F5)3, and cyanobis(pentafluoroethyl)phosphane, P(C2F5)2(CN), featuring electron withdrawing pentafluoroethyl groups, to synthesize such compounds. Metal fluorides MF (M=Ag, Cs) add to P(C2F5)3 yielding respective M[P(C2F5)3F] salts. Those M[P(C2F5)3F] subsequently suffer a loss of C2F4, furnishing M[P(C2F5)2F2]. The cesium salt decomposes instantaneously when warmed to rt, whereas the silver salt decomposes slowly over several days at rt. Treatment of Ag[P(C2F5)3F] with 2,2'‐bipyridine facilitated the isolation and structural characterization of [Ag(bipy){P(C2F5)3F}]. With P(C2F5)2(CN), AgF reacts under substitution of the cyano group yielding P(C2F5)2F, rather than phosphoranide formation. However, [K(18‐crown‐6)]F adds to P(C2F5)2(CN) furnishing [K(18‐crown‐6)][P(C2F5)2(CN)F]. Its structural characterization was successful, despite its tendency to undergo an exchange of substituents, yielding [K(18‐crown‐6)][P(C2F5)2F2] and presumably [K(18‐crown‐6)][P(C2F5)2(CN)2]. The latter forms an equilibrium with [K(18‐crown‐6)]CN and P(C2F5)2(CN) which lies well on side of the phosphane and cyanide salt. [ABSTRACT FROM AUTHOR]

A systematic investigation of imidazo- and pyrazoloiodazinium salts is presented. Besides a robust synthetic protocol that allowed us to synthesize these novel cyclic iodonium salts in their mono- and dicationic forms, we gained in-depth structural information through single-crystal analysis and demonstrated the ring opening of the heterocycle-bridged iodonium species. For an exclusive set of dicationic imidazoiodaziniums, we show highly delicate post-oxidation functionalizations retaining the hypervalent iodine center.

We describe a multi-step continuous-flow procedure for the generation of six-membered diaryliodonium salts. The accompanying scalability and atom economy are significant improvements to existing batch methods. Benzyl acetates are submitted to this two-step procedure as highly available and cheap starting materials. An acid-catalyzed Friedel–Crafts alkylation followed by an anodic oxidative cyclization yielded a defined set of cyclic iodonium salts in a highly substrate-dependent yield.

Arylation of amino‐, diamino‐ and triaminophosphines with aryl(mesityl)iodonium triflates under blue light irradiation followed by oxidative P−N bond cleavage in the in situ generated amino phosphonium salts under hydrolytic conditions represent a method for the synthesis of substituted arylphosphine oxides, arylphosphinic and arylphosphonic amides respectively. The proposed approach is based on using visible light as the only promoter for the C−P bond formation, accommodates a variety of functional groups, and can be applied to the late‐stage C−H functionalization of drug molecules. [ABSTRACT FROM AUTHOR]

A series of luminescent, neutral pentacoordinate dithieno[3,2‐b:2',3'‐d]phosphole compounds was synthesized by [4+1] cycloaddition of o‐quinones with the corresponding trivalent phospholes. The electronic and geometrical modification of the π‐conjugated scaffold implemented here impacts the aggregation behavior of the species in solution. It proved successful in generating species with improved Lewis acidity of the phosphorus center that was then leveraged for small‐molecule activation. Hydride abstraction from an external substrate involving the hypervalent species is followed by an intriguing P‐mediated umpolung from the hydride to a proton and supports the catalytic potential of this class of main‐group Lewis acids for organic chemistry. This study is a comprehensive investigation into various methods, including electronic, chemical, geometric modifications (and sometimes combinations of these approaches) to systematically improve the Lewis acidity of neutral and stable main‐group Lewis acids with practical value for a range of chemical transformations. [ABSTRACT FROM AUTHOR]

6‐Alkyl‐6‐hydroxycyclohexa‐2,4‐dienone derivatives, commonly referred to as ortho‐quinols, and their simple ester and ether variants constitute a class of organic compounds that aroused much interest amongst chemists over the past 70 years for several reasons related to organic synthesis, natural product chemistry and biochemistry. It was very early on that organic chemists understood the potential of the unique yet versatile chemical reactivity of such compounds to synthesize more complex structures, and it soon emerged that ortho‐quinols could constitute key intermediates in the biosynthesis of certain natural products of various origins. This minireview discusses the chemistry of ortho‐quinols from the point of view of their role in the synthesis and biosynthesis of natural products. Examples of completed syntheses of natural products mostly taken in the literature of the last 20 years or so, together with some chosen pieces from older but pioneering and most remarkable works, are highlighted to illustrate this discussion. [ABSTRACT FROM AUTHOR]

The enantioselective α‐oxidative coupling of enals with carboxylic acids was developed via the umpolung of an NHC‐bound enolate with an iodine(III) reagent. The corresponding α‐acyloxyl‐β,γ‐unsaturated esters were afforded in good yields, with high regio‐ and enantioselectivities. The key step of the reaction involves the formation of enol iodine(III) intermediate from the enolate with iodosobenzene, which changes the polarity of α‐carbon of the enal from nucleophilic to electrophilic, and thus facilitates the subsequent addition of carboxylate. [ABSTRACT FROM AUTHOR]

First synthesized in 1991, EthynylBenziodoXolones (EBXs) – cyclic hypervalent iodine reagents derived from 2‐iodobenzoic acid – are now among the most versatile electrophilic alkynylation reagents. Due to their cyclic structure, these reagents exhibit enhanced stability compared to previously used alkynyl iodonium salts. Over the last decade, both the iodoheterocycle and the arene ring have been extensively modified to fine‐tune the reactivity of the reagents, resulting in new analogues such as Ethynylbenziodoxoles (EBxs) or N‐heterocyclic reagents. In this article, we have for the first time compiled the structural data available for EBXs and their analogues, focusing especially on X‐Ray and NMR data. For selected compounds, molecular electrostatic potentials (MEP) have also been calculated. When considering the tight relationship between structure and reactivity in hypervalent iodine reagents, the collected data is expected to be highly useful for further developments in the field. [ABSTRACT FROM AUTHOR]

A regioselective fluorocyclisation of β,γ‐unsaturated oximes through I(I)/I(III) catalysis is disclosed to generate 5‐fluoromethylated isoxazolines. The transformation leverages p‐iodotoluene as an inexpensive catalyst, Selectfluor® as the terminal oxidant and an amine⋅HF complex (1 : 7.5) as both the fluoride and Brønsted acid source. The λ3‐iodane p‐TolIF2, which is generated in situ, engages the pendant alkene of the substrate to facilitate a cyclisation/fluorination sequence. A range of 5‐fluoromethyl isoxazolines can be generated using this method, including aliphatic and aromatic systems (up to 56 % yield). Single crystal X‐ray analysis of a representative example reveals a conformation that is consistent with the stereoelectronic gauche effect between the exocyclic C(sp3)−F bond and the C(sp3)−O of the isoxazoline (ϕOCCF=−62.0°). [ABSTRACT FROM AUTHOR]

In this study, we afford explicit characterizations of the electronic and geometrical structures of recently reported hypervalent penta‐coordinate carbon compounds by using gas‐phase characterization techniques: photodissociation spectroscopy (PDS) and ion mobility‐mass spectrometry (IM–MS). In particular for a compound with moderately electron‐donating ligands, bearing p‐methylthiophenyl substituents, the coexistence of tetra‐ and penta‐coordinate isomers is confirmed, consistent with solution characterizations. It is in sharp contrast to the exclusive tetra‐coordinate form (with normal valence of the central carbon atom) in the single crystal. This suggests that a non‐polar environment makes the penta‐coordinate structure thermodynamically most stable. This delicate difference between the tetra‐ and penta‐coordinate structures, which depends on the environment, is a close reflection of the lower activation barrier of the SN2 reaction found in neutral solvent or gas‐phase reactions. [ABSTRACT FROM AUTHOR]

Efficient protocols for accessing iodo‐substituted diaryl and aryl(vinyl) sulfides have been developed using iodonium salts as reactive electrophilic arylation and vinylation reagents. The reactions take place under transition‐metal‐free conditions, employing odorless and convenient sulfur reagents. A wide variety of functional groups are tolerated in the S‐diarylation, enabling the regioselective late‐stage application of several heterocycles and drug molecules under mild reaction conditions. A novel S‐difunctionalization pathway was discovered using vinyliodonium salts, which proceeds under additive‐free reaction conditions and grants excellent stereoselectivity in the synthesis of aryl(vinyl) sulfides. A one‐pot strategy combining transition‐metal‐free diarylation and subsequent reduction provided facile access to electron‐rich thioanilines and a direct synthesis of a potential drug candidate derivative. The retained iodo group allows a wide array of further synthetic transformations. Mechanistic insights were elucidated by isolating the key intermediate, and the relevant energy profile was substantiated by DFT calculations. [ABSTRACT FROM AUTHOR]

Alkynes and nitriles are valuable building blocks in organic synthesis and also have multiple applications in chemical biology and materials science. Due to the high availability of tertiary alcohols, developing methods for their conversion into alkynes and nitriles is particularly attractive. In a previous communication, our group has reported the conversion of alcohols into alkynes through cesium oxalates based on the powerful combination of photochemistry with Ethynyl BenziodoXolones (EBXs). Herein, we report further investigations into this transformation, including our findings on the effect that backbone modification of EBXs has on the deoxyalkynylation of cesium oxalates. In addition, we disclose preliminary data on the development of new deoxycyanation and dethioalkynylation processes. We also report the serendipitous discovery of the C−H alkynylation of 1,2‐dichloroethane. [ABSTRACT FROM AUTHOR]

The first systematic evaluation of the electrostatic potential energy maps of iodonium ylides was conducted. We determined that they possess two σ‐holes of differing electron deficiencies, with the more electropositive σ‐hole located opposite the dative I−C bond to the β‐dicarbonyl motif, and the lesser electropositive σ‐hole located opposite the iodoarene C−I bond. We also conducted the first systematic evaluation of carboxylic acids, phenols and thiophenols in the O/S‐alkylation reaction of iodonium ylides. While carboxylic acids and thiophenols were found to be generally viable, only phenols possessing electron‐withdrawing substituents were effective. This high‐yielding and highly chemoselective reaction is believed to involve halogen‐bond activation of heteroatoms, and nicely complements existing diazo‐based methods for alkylation of acidic functional groups. [ABSTRACT FROM AUTHOR]

Two regioselective, high‐yielding one‐pot routes to oxygen‐bridged cyclic diaryliodonium salts and ortho‐aryloxy‐substituted acyclic diaryliodonium salts are presented. Starting from easily available ortho‐iodo diaryl ethers, complete selectivity in formation of either the cyclic or acyclic product could be achieved by varying the reaction conditions. The complimentary reactivities of these novel ortho‐oxygenated iodonium salts were demonstrated through a series of chemoselective arylations under metal‐catalyzed and metal‐free conditions, to deliver a range of novel, ortho‐functionalized diaryl ether derivatives. [ABSTRACT FROM AUTHOR]

Experimental evidence for hypervalent compounds of second-row elements is still scarce in literature. Here, we present the first report of the long-sought binary, hypervalent trifluorooxygenate anion [OF 3 ] - . It was isolated in solid Ne matrices under cryogenic conditions after reacting oxygen difluoride with free fluoride ions from laser ablation of alkali metal fluorides MF (M=Li-Cs). VSEPR theory and calculations at the CCSD(T) level predict a C 2v -symmetric T-shape structure with one short and two long O-F bond lengths in [OF 3 ] - . This is confirmed experimentally by FTIR spectroscopy in combination with isotopic labeling. Analysis of the natural local molecular orbitals shows the presence of one 2c-2e and one 3c-4e bond each. Natural resonance theory indicates the importance of the stability of [OF 2 ]⋅ - for the stability of [OF 3 ] - . Although free [OF 2 ]⋅ - was not detected, the species MOF 2 (M=Na-Cs) could be observed in the same experiments, which are best described as contact ion pairs of M + [OF 2 ]⋅ - ., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Organic azides have found wide application in various fields of science and technology. This review summarizes recently developed approaches to the direct, one‐step synthesis of diverse organic azides utilizing hypervalent iodine reagents. The first part of review deals with the azidation using unstable azidoiodinanes generated in situ from common hypervalent iodine reagents (such as diacetoxyiodobenzene or iodosylbenzene) and a source of azide anion (TMSN3 or NaN3). The second part of review is dedicated to the application of stable azidobenziodoxoles as useful azidating reagents that allow selective direct azidation of C−H bonds or double carbon‐carbon bonds under mild reaction conditions. The use of azidobenziodoxoles eliminates the main disadvantages of the traditional approaches to organic azides, such as the need in pre‐functionalization of organic substrates and harsh reaction conditions. Synthetic application of azidobenziodoxoles made possible direct selective azidation of a plethora of organic substrates including complex molecules at the late synthetic stage. [ABSTRACT FROM AUTHOR]

The iodination of calix[4]arene and one of its monofunctionalised derivatives by bis(pyridine)iodonium(I) triiodide, [I(py)2]I3·2I2 has been studied. The iodination reactions proceed in good yields at room temperature (r.t.) without any co-reagents affording the corresponding tetra- and tri-substituted calix[4]arenes. Only electron-rich phenol groups are iodinated by [I(py)2]I3·2I2. Phenolether or Schiff-base type arene rings remain unaffected. The crystal structure of the iodination reagent, first published in 1961, has been re-determined which a higher precision. The crystal structures of the two per-iodinated calix[4]arenes show that self-inclusion occurs in the solid state. [I(py)2]I3·2I2 selectively iodinates electron-rich phenol groups of calix[4]arenes. Less electron-rich aryl rings remain unaffected. Self-inclusion of iodinated calix[4]arenes occurs in the solid state. [ABSTRACT FROM AUTHOR]

The iodination of calix[4]arene and one of its monofunctionalised derivatives by bis(pyridine)iodonium(I) triiodide, [I(py)2]I3·2I2 has been studied. The iodination reactions proceed in good yields at room temperature (r.t.) without any co-reagents affording the corresponding tetra- and tri-substituted calix[4]arenes. Only electron-rich phenol groups are iodinated by [I(py)2]I3·2I2. Phenolether or Schiff-base type arene rings remain unaffected. The crystal structure of the iodination reagent, first published in 1961, has been re-determined which a higher precision. The crystal structures of the two per-iodinated calix[4]arenes show that self-inclusion occurs in the solid state. [I(py)2]I3·2I2 selectively iodinates electron-rich phenol groups of calix[4]arenes. Less electron-rich aryl rings remain unaffected. Self-inclusion of iodinated calix[4]arenes occurs in the solid state. [ABSTRACT FROM AUTHOR]

Vinylbenziodoxolones have recently been identified as efficient hypervalent iodine(III) reagents for electrophilic vinylations under transition metal‐free conditions. Their unique reactivity allows synthesis of either internal or terminal alkenes, depending on the nucleophile class. This paper constitutes the first mechanistic investigation of VBX vinylations, and makes use of NMR studies, deuterium labelling and computations to rationalize the observed regio‐ and stereochemical outcome. Internal alkene formation in S‐vinylation was found to proceed through the ligand coupling mechanism typical of diaryliodonium salts, whereas terminal alkene formation in P‐vinylations took place via a phosphinous acid‐coordinated VBX complex, which underwent concerted deprotonation and Michael‐type addition. Subsequent base‐assisted protonation and E2 elimination delivered the terminal alkene. The findings can be used to predict the regioselectivity in vinylations of other nucleophile classes. [ABSTRACT FROM AUTHOR]

Truxene is a C3‐symmetric compound with characteristic photophysical properties, and it has great potential as a light‐emitting material and building block. In this study, we demonstrate the synthesis of hexaazatruxenes using a two‐step protocol. First, the hexaazatruxene precursors were prepared through the Buchwald‐Hartwig amination of 1,3,5‐tribromobenzene with commercially available or easily prepared amino‐pyridine derivatives. Then, hexaazatruxenes were synthesized through consecutive N−H/C−H coupling using a hypervalent iodine reagent. To the best of our knowledge, this is the first report on the synthesis of truxenes containing more than three heteroatoms in the main skeleton. [ABSTRACT FROM AUTHOR]

A two‐step strategy for the transition‐metal‐free C−H functionalization of arenes using unsymmetrical iodonium salts as versatile synthetic linchpins is presented. The key to the success of this strategy is the identification of the 3,5‐dimethyl‐4‐isoxazolyl (DMIX) group as a superior dummy ligand, which enables not only site‐selective C−H functionalization to afford unsymmetrical iodonium salts, but also highly selective aryl transfer during the subsequent metal‐free coupling reaction. Both electron‐rich and moderately electron‐deficient arenes can be converted into the iodonium salts through C−H functionalization, allowing for diverse structural elaboration by metal‐free C−N, C−C, C−S, and C−O coupling. [ABSTRACT FROM AUTHOR]

Arylation of tertiary aryl and alkyl phosphines bearing 2‐cyanoethyl group with aryl(mesityl)iodonium triflates under blue light irradiation followed by retro‐Michael reaction of the in situ generated quaternary phosphonium salts initiated by DBU represent a novel efficient and general method for the preparation of distinctly substituted tertiary arylphosphines. An operationally simple, one‐pot protocol features mild, transition‐metal‐free conditions, high selectivity, broad functional group compatibility, as well as scalability and would be applied to substrates with different electronic and steric nature. [ABSTRACT FROM AUTHOR]

A systematic investigation of ethynyl N‐heterocycle‐substituted‐λ3‐iodanes (ENHIs) is presented. In a straightforward one‐pot synthesis these novel reagents can be obtained in high yields bearing a variety of N‐heterocycles. Their reactivity as electrophilic alkyne group transfer reagents was benchmarked in well‐established and novel inter‐ and intramolecular group transfer reactions. [ABSTRACT FROM AUTHOR]

This review outlines the progress over recent years in the reactions involving combined approach of hypervalent iodine reagents and transition metals such as palladium, nickel, iridium, gold, rhodium, copper, iron, ruthenium, platinum, silver, zinc, rhenium and cobalt. This approach enables organic transformations complimentary to traditional manifolds. Hypervalent iodine reagents play a preeminent role in organic chemistry due to their versatile reactivity, heteroatom ligands and mild reaction conditions. These reagents in combination of transition metal compounds are used in many synthetically useful organic reactions such as oxidation, rearrangement, amination, halogenation, amidation, ring‐opening, cyclization and C−H and C−C functionalization reactions, etc. which are discussed here. [ABSTRACT FROM AUTHOR]

We disclose a new reactivity mode for electrophilic cyano λ3‐iodanes as group transfer one‐electron oxidants to synthesize FeIII and FeIV cyanide complexes. The inherent thermal instability of high‐valent FeIV compounds without π‐donor ligands (such as oxido (O2−), imido (RN2−) or nitrido (N3−)) makes their isolation and structural characterization a very challenging task. We report the synthesis of an FeIV cyanide complex [(N3N′)FeCN] (4) by two consecutive single electron transfer (SET) processes from FeII precursor [(N3N′)FeLi(THF)] (1) with cyanobenziodoxolone (CBX). The FeIV complex can also be prepared by reaction of [(N3N′)FeIII] (3) with CBX. In contrast, the oxidation of FeII with 1‐cyano‐3,3‐dimethyl‐3‐(1H)‐1,2‐benziodoxole (CDBX) enables the preparation of FeIII cyanide complex [(N3N′)FeIII(CN)(Li)(THF)3] (2‐LiTHF). Complexes 4 and 2‐LiTHF have been structurally characterized by single crystal X‐ray diffraction and their electronic structure has been examined by Mössbauer, EPR spectroscopy, and computational analyses. [ABSTRACT FROM AUTHOR]

Phosphoranides are interesting hypervalent species which serve as model compounds for intermediates or transition states in nucleophilic substitution reactions at trivalent phosphorus substrates. Herein, the syntheses and properties of stable trifluoromethylphosphoranide salts are reported. [K(18‐crown‐6)][P(CF3)4], [K(18‐crown‐6)][P(CF3)3F], and [NMe4][P(CF3)2F2] were obtained by treatment of trivalent precursors with sources of CF3− or F− units. These [P(CF3)4‐nFn]− (n=0–2) salts exhibit fluorinating (n=1–2) or trifluoromethylating (n=0) properties, which is disclosed by studying their reactivity towards selected electrophiles. The solid‐state structures of [K(18‐crown‐6)][P(CF3)4] and [K(18‐crown‐6)][P(CF3)3F] are ascertained by single crystal X‐ray crystallography. The dynamics of these compounds are investigated by variable temperature NMR spectroscopy. [ABSTRACT FROM AUTHOR]

The direct and catalytic incorporation of fluorine containing molecular motifs into organic compounds resulting high‐value added chemicals represents a rapidly evolving part of synthetic methodologies, thus this area is in the focus of pharmaceutical and agrochemical research. Herein we report a stereoselective procedure for direct fluorovinylation of aromatic and heteroaromatic scaffolds. This methodology development has been realized by palladium‐catalyzed ortho C−H activation reaction of aniline derivatives featuring the regioselectivity via directing groups such as secondary of tertiary amides, ureas or ketones. The application of non‐symmetrical aryl(fluoroalkenyl)‐iodonium salts as fluoroalkenylating agents allowed mild reaction conditions in general for this transformation. The scope and limitations have been thoroughly investigated and the feasibility has been demonstrated by more than 50 examples. [ABSTRACT FROM AUTHOR]

We report a facile, transition metal-free synthesis of fluorobenzoic acids by nucleophilic fluorination of readily available 1-arylbenziodoxolones using fluoride salts in polar aprotic solvents. This protocol was applied for the preparation of 2-[18F]-fluoro-5-nitrobenzoic acid, which is a potentially important radioligand for Positron Emission Tomography (PET). [ABSTRACT FROM AUTHOR]

The chemistry of hypervalent iodine compounds has been widely recognized in the synthetic community. The utilization of hypervalent iodine compounds as stoichiometric reagents as well as catalysts has tremendously been studied in recent decades. Hypervalent iodine (V)-catalyzed reactions are proven to be versatile catalytic systems to access various oxidative transformations. In this review, the versatility of hypervalent iodine (V)- catalyzed reactions have been discussed in detail. This review highlights the oxidation of various substrates using catalytic amounts of o-iodoxybenzoic acid (IBX), modified IBX derivatives, o-iodoxybenzenesulfonic acid (IBS), recyclable iodine (V), and non-cyclic/pseudocyclic iodine (V) compounds. [ABSTRACT FROM AUTHOR]

We report a facile synthesis of triarylsulfonium triflates by selective aryl transfer from readily available mesityl iodonium(III) salts to diarylsulfides in the presence of a copper catalyst. The advantage of our protocol is that the iodonium(III) salts bearing a mesitylene (Mes) auxiliary efficiently promote selective S-arylation of diarylsulfides to produce the desired triarylsulfonium triflates without the formation of Mes-derived byproduct salts. [ABSTRACT FROM AUTHOR]

Hypervalent iodine reagents are powerful tools in contemporary organic synthesis. They have found numerous applications in modern oxidative transformations. The unique reactivity of hypervalent iodine allows access to unconventional electrophilic synthons. For example, electrophilic halogenation chemistry has been greatly expanded by the study of various haloiodanes. Cyclic λ3‐haloiodanes are versatile reagents which can promote reactions such as halogenations, halocyclizations and oxidations. Their peculiar reactivity sets them apart from traditional sources of electrophilic halogens. Furthermore, they offer a broad range of reactivities which have been exploited in more diversified transformations. This review summarizes the different syntheses and derivatives of these cyclic haloiodanes, their applications and mechanistic insights as well as the relevant computational, structural and kinetic studies. [ABSTRACT FROM AUTHOR]

Thiol‐mediated uptake is emerging as method of choice to penetrate cells. This study focuses on irreversible covalent inhibitors of thiol‐mediated uptake. High‐content high‐throughput screening of the so far largest collection of hypervalent iodine reagents affords inhibitors that are more than 250 times more active than Ellman's reagent and rival the best dynamic covalent inhibitors. Comparison with other irreversible reagents reveals that inhibition within one series follows reactivity, whereas inhibition across series deviates from reactivity. These trends support that molecular recognition, besides dynamic covalent exchange, contributes significantly to thiol‐mediated uptake. The most powerful inhibitors besides the best hypervalent iodine reagents were Fukuyama's nosyl protecting group and super‐cinnamaldehydes that have been introduced as irreversible activators of the pain receptor TRPA1. Considering that several viruses use different forms of thiol‐mediated uptake to enter cells, the identification of new irreversible inhibitors of thiol‐mediated uptake is of general interest for the discovery of new antivirals. [ABSTRACT FROM AUTHOR]

Many natural products of plant or microbial origins are derived from enzymatic dearomative oxygenation of 2‐alkylphenolic precursors into 6‐alkyl‐6‐hydroxycyclohexa‐2,4‐dienones. These so‐called ortho‐quinols cyclodimerize via a remarkably selective bispericyclic Diels–Alder reaction. Whether or not the intervention of catalytic or dirigent proteins is involved during this final step of the biosynthesis of these natural products, this cyclodimerization of ortho‐quinols can be chemically reproduced in the laboratory with the same strict level of site‐specific regioselectivity and stereoselectivity. This unique yet unified process, which finds its rationale in the inherent chemical reactivity of those ortho‐quinols, is illustrated herein by an efficient and bioinspired first chemical synthesis of one of the most structurally complex and synthetically challenging examples of such natural cyclodimers, the bisditerpenoid (+)‐maytenone. [ABSTRACT FROM AUTHOR]

The coordination chemistry of KrF2 has been limited in contrast with that of XeF2, which exhibits a far richer coordination chemistry with main‐group and transition‐metal cations. In the present work, reactions of [XeF5][AsF6] with KrF2 in anhydrous HF solvent afforded [F5Xe(FKrF)AsF6] and [F5Xe(FKrF)2AsF6], the first mixed krypton/xenon compounds. X‐ray crystal structures and Raman spectra show the KrF2 ligands and [AsF6]− anions are F‐coordinated to the xenon atoms of the [XeF5]+ cations. Quantum‐chemical calculations are consistent with essentially noncovalent ligand−xenon bonds that may be described in terms of σ‐hole bonding. These complexes significantly extend the XeF2–KrF2 analogy and the limited chemistry of krypton by introducing a new class of coordination compound in which KrF2 functions as a ligand that coordinates to xenon(VI). The HF solvates, [F5Xe(FH)AsF6] and [F5Xe(FH)SbF6], are also characterized in this study and they provide rare examples of HF coordinated to xenon(VI). [ABSTRACT FROM AUTHOR]

The coordination chemistry of KrF2 has been limited in contrast with that of XeF2, which exhibits a far richer coordination chemistry with main‐group and transition‐metal cations. In the present work, reactions of [XeF5][AsF6] with KrF2 in anhydrous HF solvent afforded [F5Xe(FKrF)AsF6] and [F5Xe(FKrF)2AsF6], the first mixed krypton/xenon compounds. X‐ray crystal structures and Raman spectra show the KrF2 ligands and [AsF6]− anions are F‐coordinated to the xenon atoms of the [XeF5]+ cations. Quantum‐chemical calculations are consistent with essentially noncovalent ligand−xenon bonds that may be described in terms of σ‐hole bonding. These complexes significantly extend the XeF2–KrF2 analogy and the limited chemistry of krypton by introducing a new class of coordination compound in which KrF2 functions as a ligand that coordinates to xenon(VI). The HF solvates, [F5Xe(FH)AsF6] and [F5Xe(FH)SbF6], are also characterized in this study and they provide rare examples of HF coordinated to xenon(VI). [ABSTRACT FROM AUTHOR]