Search

Hypervalent iodine reagents are versatile and readily accessible reagents that have been extensively applied in contemporary synthesis in modern organic chemistry. Among them, iodonitrene (ArI=NR), is a powerful reactive species, widely used for a single‐nitrogen‐atom insertion reaction, and skeletal editing to construct N‐heterocycles. Skeletal editing with reactive iodonitrene components has recently emerged as an exciting approach in modern chemical transformation. These reagents have been extensively used to produce biologically relevant heterocycles and functionalized molecular architectures. Recently, the insertion of a nitrogen‐atom into hydrocarbons to generate N‐heterocyclic compounds using hypervalent iodine reagents has been a significant focus in the field of molecular editing reactions. In this review, we discuss the rapidly emerging field of nitrene insertion, including skeletal editing and nitrogen insertion, using hypervalent iodine reagents to access nitrogen‐containing heterocycles, and the current mechanistic understanding of these processes. [ABSTRACT FROM AUTHOR]

A hypervalent iodine(III)-mediated C(sp3)–C(sp3) bond functionalization reaction for the formation of C–C, C–P, and C–H bonds in dihydroquinazolines has been developed. This one-pot method involves successive oxidation of dihydroquinazoline substrates, mesolytic cleavage of a tert-butyl substituent, and bond formation to a variety of nucleophiles in moderate to high yields. [ABSTRACT FROM AUTHOR]

Chalcogen bond (ChB) catalysis, as a new type in the field of non‐covalent bond catalysis, has become a hot research topic in the field of organocatalysis in recent years. In the present work, we investigated the catalytic performance of a series of hypervalent ChB catalysis based on the intramolecular Aza‐Michael reaction of aminochalcone. The reaction includes the carbon‐nitrogen bond coupling step (key step) and the proton transfer step. The catalytic performance of mono‐dentate pentafluorophenyl chalcogen bond donor ChB1 was comparable to that of bis‐dentate chalcogen bond donor ChB4, and stronger than that of mono‐dentate chalcogen bond donors ChB2 and ChB3. The formation of the chalcogen bond between the catalyst and the carbonyl oxygen atom of the reactant, causing the charge rearrangement of the reactant and C(1) charge of the −C−Ph group to become more positive, thereby the ChB catalysis promoted the nucleophile reaction. The electron density of the chalcogen bond of the pre‐complex, the most positive electrostatic potentials of the catalyst, and the NPA charge of the key atom are proportional to the Gibbs energy barrier of the C−N bond coupling process, which provides an idea to predict the catalytic activity of the ChB catalysis. [ABSTRACT FROM AUTHOR]

Halogen(I) complexes are widely used as halogenation reagents and traditionally feature homoleptic stabilising Lewis bases, though the recent revitalisation of iodine(I) carboxylate chemistry has provided isolable examples of heteroleptic iodine(I) complexes. This work reports iodine(I) pnictogenate complexes stabilised by a Lewis base (L), Ph2P(O)O─I─L, synthesised via cation exchange from the silver(I) precursor, (Ph2P(O)OAg)n. The complexes were characterised in both solution (1H, 1H-15N HMBC, 31P) and the solid state, and supplemented computationally by DFT studies. Interestingly, these iodine(I) pnictogenates demonstrate a range of stabilities, and have been found to excel as iodination reagents in comparison to carbonyl hypoiodites, with comparable reactivity to the eponymous Barluenga's reagent in the iodination of antipyrine. Iodine(I) carboxylates have been explored as iodination reagents, but the role of the carbonyl group in promoting such reactivity remains poorly understood. Here, the authors prepare iodine(I) pnictogenates and find that they excel as iodination reagents in comparison to iodine(I) carboxylates. [ABSTRACT FROM AUTHOR]

Lewis acidic boron compounds are ubiquitous in chemistry due to their numerous applications, yet tuning and optimizing their properties towards different purposes is still a challenging field of research. In this work, the boron‐based Lewis acid B[OTeF3(C6F5)2]3 was synthesized by reaction of the teflate derivative HOTeF3(C6F5)2 with BCl3 or BCl3 ⋅ SMe2. This new compound presents a remarkably high thermal stability up to 300 °C, as well as one of the most sterically encumbered boron centres known in the literature. Theoretical and experimental methods revealed that B[OTeF3(C6F5)2]3 exhibits a comparable Lewis acidity to that of the well‐known B(C6F5)3. The affinity of B[OTeF3(C6F5)2]3 towards pyridine was accessed by Isothermal Titration Calorimetry (ITC) and compared to that of B(OTeF5)3 and B(C6F5)3. The ligand‐transfer reactivity of this new boron compound towards different fluorides was demonstrated by the formation of an anionic Au(III) complex and a hypervalent iodine(III) species. [ABSTRACT FROM AUTHOR]

In the last few years, a controversy has been raised regarding the nature of the chemical bonding present in phase change materials (PCMs), many of which are minerals such as galena (PbS), clausthalite (PbSe), and altaite (PbTe). Two opposite bonding models have claimed to be able to explain the extraordinary properties of PCMs in the last decade: the hypervalent (electron-rich multicenter) bonding model and the metavalent (electron-deficient) bonding model. In this context, a third bonding model, the electron-deficient multicenter bonding model, has been recently added. In this work, we comment on the pros and cons of the hypervalent and metavalent bonding models and briefly review the three approaches. We suggest that both hypervalent and metavalent bonding models can be reconciled with the third way, which considers that PCMs are governed by electron-deficient multicenter bonds. To help supporters of the metavalent and hypervalent bonding model to change their minds, we have commented on the chemical bonding in GeSe and SnSe under pressure and in several polyiodides with different sizes and geometries. [ABSTRACT FROM AUTHOR]

Halogen bonding acknowledged as a noteworthy weak interaction, has gained growing recognition in the field of supramolecular chemistry. In this study, we selected structurally rigid diaryliodonium ions (I(III)) with two biaxial σ‐holes as halogen‐bond donors, to bind with three chiral acceptor molecules bearing cholesteryl and naphthalimides with distinct geometries. The abundant carbonyl oxygen atoms in side‐arm substituents function as multiple acceptors for halogen bonding. The self‐aggregation of chiral acceptor molecules demonstrates adaptiveness to solvent media, evidenced by the inversion of the Cotton effect and the morphological evolution from spherical to rod‐like nanoarchitectures in different solvent systems. The distinct geometries of the acceptor molecules conferred various binding modes with I(III). The introduction of I(III) as a halogen‐bond donor regulates the aggregation of the donors, achieving amplification of chiroptical signals and inheriting solvent responsiveness from the self‐aggregated assembly. This study successfully utilized rational structural design and multimodal control strategies to achieve regulation of supramolecular chirality. [ABSTRACT FROM AUTHOR]

We report, an intramolecular ipso‐halocyclization of N‐arylpropynamides using readily available hypervalent iodine reagent as mild oxidant and alkali halides like KCl, KBr, and KI as the halogen source. Using this method, a broad range of valuable halogenated spiro[4.5]trienones can be obtained in an excellent yield at room temperature. Notably, this protocol doesn't require para‐substituents such as methoxy or fluoro group on the N‐aryl ring. Also, this reaction takes place in the absence of any metal catalyst under aqueous conditions and exhibits a broad substrate scope with high functional group tolerance. A plausible reaction mechanism is proposed based on control experiments. [ABSTRACT FROM AUTHOR]

The direct trifluoromethylthiolation of terminal alkynes is an important strategy for accessing CF3S-containing compounds. Herein, we report a direct trifluoromethylthiolation reaction of various terminal alkynes employing a new hypervalent trifluoromethylthio-iodine(III) reagent TFTI in a fluorinated alcohol, either 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) or perfluoro-tert-butanol (PFTB). The reaction mechanism is proposed on the basis of experiments and DFT calculations. The sustainability of TFTI and the recovery of PFTB make the reaction environmentally friendly. And, the protocol was found to be an excellent one in the context of green chemistry based on green chemistry metrics evaluation and EcoScale score. [ABSTRACT FROM AUTHOR]

N‐Heterocyclic amines have been known as an important class of nitrogen‐containing molecules with a wide range of applications. Described here is a mild and efficient electrochemical desulfurizative amination of readily accessible heteroaromatic thiols without necessity of metal catalyst. The key to success for this reaction is the in‐situ generation of a hypervalent iodine reagent as an organocatalyst from iodoarene by anodic oxidation. This mild desulfurizative amination presents ample substrate scope and good functional group tolerance without the use of extra stoichiometric chemical oxidants. As only electrons serve as the oxidation reagents, this method offers a straightforward and sustainable manner towards versatile N‐heterocyclic amines, including late‐stage functionalization of pharmaceutically relevant molecules. [ABSTRACT FROM AUTHOR]

This review summarizes the structural and synthetic aspects of heterocyclic molecules incorporating an atom of a hypervalent main-group element. The term "hypervalent" has been suggested for derivatives of main-group elements with more than eight valence electrons, and the concept of hypervalency is commonly used despite some criticism from theoretical chemists. The significantly higher thermal stability of hypervalent heterocycles compared to their acyclic analogs adds special features to their chemistry, particularly for bromine and iodine. Heterocyclic compounds of elements with double bonds are not categorized as hypervalent molecules owing to the zwitterionic nature of these bonds, resulting in the conventional 8-electron species. This review is focused on hypervalent heterocyclic derivatives of nonmetal main-group elements, such as boron, silicon, nitrogen, carbon, phosphorus, sulfur, selenium, bromine, chlorine, iodine(III) and iodine(V). [ABSTRACT FROM AUTHOR]

This mini review article provides an overview on the use of hypervalent iodine compounds (HICs) in carbohydrate synthesis, focusing on their chemistry and recent applications. HICs are similar to transition metals in their reactivity but have the added benefit of being environmentally benign, and are therefore commonly used as selective oxidants and eco‐friendly reagents in organic synthesis. Herein, we summarize various synthetic uses of hypervalent iodine reagents in reactions such as glycosylation, oxidations, functionalization, and C−C bond‐forming reactions. The goal of this review is to illustrate the advantages and versatility of using HICs as an environmentally sustainable alternative to heavy metals in carbohydrate chemistry. [ABSTRACT FROM AUTHOR]

We studied intramolecular noncovalent bonds in organogermanium or organosilicon cyclic esters of tris(2-hydroxyalkyl)amines called silatranes and germatranes. We have shown that the N...Si and N...Ge interactions, well known as hypervalent or transannular bonds, can be rightfully categorized as the strong tetrel bonds (TtB). In the wide set of silatranes and germatranes, the TtB strength is under the influence of the Y substituent at Tt atom in the N...Tt–Y fragment and the features of crystalline environment. We have disclosed the quantitative trends in electronic features of N...Tt tetrel bonds and demonstrated the applicability of criteria based on the positions of extremes in electron density and electrostatic potential along the line between N and Tt atoms to compare the strength of the N...Si and N...Ge tetrel bonds. An important observation is that the dependence of gap width on bond lengths is not linear for silatranes. In order to solve this problem we have analyzed the features of total static potential. The gap between positions of extremes in electrostatic and total static potentials is wide for the weak tetrel bonds and narrow for the strong ones. [ABSTRACT FROM AUTHOR]

Chalcogen bond catalysis, particularly cationic hypervalent chalcogen bond catalysis, is considered to be an effective strategy for organocatalysis. In this work, the cationic hypervalent chalcogen bond catalysis for the Povarov reaction between N‐benzylideneaniline and ethyl vinyl ether was investigated by density functional theory (DFT). The catalytic reaction involves the cycloaddition process and the proton transfer process, and the rate‐determining step is the cycloaddition process. Cationic hypervalent tellurium derivatives bearing CF3 and F groups exhibit superior catalytic activity. For the rate‐determining step, the Gibbs free energy barrier decreases as the positive electrostatic potential of the chalcogen bond catalysts increases. More importantly, the Gibbs free energy barrier has a strong linear correlation with the electrostatic energy of the chalcogen bond in the catalyst‐substrate complex. Furthermore, the catalytic reactions include the endo pathway and exo pathway. The C−H⋅⋅⋅π interaction between the substituent of the ethyl vinyl ether and the aryl ring of the N‐benzylideneaniline contributes to the endo‐selectivity of the reaction. This research contributes to a deeper understanding of chalcogen bond catalysis, providing insights for designing chalcogen bond catalysts with high performance. [ABSTRACT FROM AUTHOR]

One of the most useful transformations in the synthetic chemist arsenal is the oxidation of alcohols to their corresponding carbonyl congeners. Despite its seemingly straightforward nature, this transformative reaction predominantly relies on the use of metals or hazardous reagents, making these processes highly unsustainable. To address this challenge, we have developed a sustainable metal‐free method for the oxidation of alcohols in continuous flow. Using a solid phase hypervalent iodine catalyst and nBu4HSO5 as a phase transfer catalyst and co‐oxidant, primary and secondary alcohols were selectively oxidized to the corresponding carbonyl motifs. This operationally simple continuous‐flow set‐up is highly robust (15 cycles run without significant catalyst leaching or loss of reaction efficiency), uses green solvents, such as acetonitrile or acetic acid, and is readily scalable. [ABSTRACT FROM AUTHOR]

This article discusses the synthesis of 5-Hydroxyuridine (5-OHU) and its formation in bacterial tRNA. The authors explore the reaction mechanism and the impact of different parameters on the yield of the desired compounds. They also discuss the conformation of nucleosides, specifically focusing on the sugar geometry and its influence on the overall structure. The study utilizes various techniques to analyze the sugar conformation and its impact on the nucleoside structure. Overall, this research provides insights into the synthesis and properties of 5-hydroxuridine, an important RNA lesion. [Extracted from the article]

Kinetics of the reactions of colored carbanions (reference nucleophiles) with S‐(trifluoromethyl)dibenzothiophenium ions (Umemoto's reagents) and hypervalent trifluoromethyl‐substituted iodine compounds (Togni's reagents) have been determined photometrically using stopped‐flow techniques. The second‐order rate constants k2(20 °C) for the reactions of Umemoto's sulfonium ions (generation I and II) with the reference nucleophiles in DMSO follow the correlation lg k2(20 °C)=sN(N+E) and can be used to determine the electrophilicity parameters E of these trifluoromethylating reagents. It is shown that the conditions reported for the reactions of Umemoto's generation I reagents with a variety of C‐nucleophiles are in line with the electrophilicity parameter E≈−13 determined for these reagents. Though Togni's hypervalent iodine‐based trifluoromethylation reagents do not follow this linear free energy relationship, the kinetics of their reactions with carbanions indicate that they cover the same reactivity range as Umemoto's generation I and II reagents. [ABSTRACT FROM AUTHOR]

A catalyst‐free intermolecular dearomatization reaction of β‐naphthols with hypervalent‐iodine‐based nitrooxylating reagent is reported. Various nitrooxylated β‐naphthalenones bearing a quaternary carbon stereogenic center were obtained smoothly in good to excellent yields (up to 87 %) under mild conditions. This method features mild conditions, broad substrate scope and excellent chemoselectivity. [ABSTRACT FROM AUTHOR]

The transition-metal free S-vinylation of thiophenols by vinylbenziodoxolones (VBX) constituted an important step forward in hypervalent iodine-mediated vinylations, highlighting the difference to vinyliodonium salts and that the reaction outcome was influenced by the substitution pattern of the benziodoxolone core. In this study, we report several new classes of hypervalent iodine vinylation reagents; vinylbenziodazolones, vinylbenziodoxolonimine and vinyliodoxathiole dioxides. Their synthesis, structural and electronic properties are described and correlated to the S-vinylation outcome, shedding light on some interesting facets of these reagents. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A metal‐free, green, and sustainable functionalization of unactivated alkyl sp3 C—H bonds is reported using iodine(III) as a feasible dehydrogenation agent under visible light or KBr, and alkyl chlorides, bromides, alcohols, and ketones could be constructed by addition of different coupling reagents. Cheap and safe iodobenzene diacetate was used to form a radical to activate the alkyl sp3 C—H bond in a highly efficient manner, which can construct different alkylation products by adding corresponding coupling reagents. [ABSTRACT FROM AUTHOR]

We report herein an unprecedented hypervalent iodine(III)‐catalysis using the activated sulfoxide. Since the present catalytic systems promote the dehydrogenative cycloisomerization‐arylation reaction of 2‐propargyl 1,3‐dicarbonyl compounds with aromatics, this report also provides one of the few methods for iodine(III)‐catalyzed intermolecular carbon‐carbon bond formation of aromatics. [ABSTRACT FROM AUTHOR]

A family of solids including crystalline phase change materials such as GeTe and Sb2Te3, topological insulators like Bi2Se3, and halide perovskites such as CsPbI3 possesses an unconventional property portfolio that seems incompatible with ionic, metallic, or covalent bonding. Instead, evidence is found for a bonding mechanism characterized by half‐filled p‐bands and a competition between electron localization and delocalization. Different bonding concepts have recently been suggested based on quantum chemical bonding descriptors which either define the bonds in these solids as electron‐deficient (metavalent) or electron‐rich (hypervalent). This disagreement raises concerns about the accuracy of quantum–chemical bonding descriptors is showed. Here independent of the approach chosen, electron‐deficient bonds govern the materials mentioned above is showed. A detailed analysis of bonding in electron‐rich XeF2 and electron‐deficient GeTe shows that in both cases p‐electrons govern bonding, while s‐electrons only play a minor role. Yet, the properties of the electron‐deficient crystals are very different from molecular crystals of electron‐rich XeF2 or electron‐deficient B2H6. The unique properties of phase change materials and related solids can be attributed to an extended system of half‐filled bonds, providing further arguments as to why a distinct nomenclature such as metavalent bonding is adequate and appropriate for these solids. [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]

Gold redox catalysis, often facilitated by hypervalent iodine(III) reagents, offers unique reactivity but its progress is mainly hindered by an incomplete mechanistic understanding. In this study, we investigated the reaction between the gold(I) complexes [(aryl)Au(PR3)] and the hypervalent iodine(III) reagent PhICl2, both experimentally and computationally and provided an explanation for the formation of divergent products as the ligands bonded to the gold(I) center change. We tackled this essential question by uncovering an intriguing transmetalation mechanism that takes place between gold(I) and gold(III) complexes. We found that the ease of transmetalation is governed by the nucleophilicity of the gold(I) complex, [(aryl)Au(PR3)], with greater nucleophilicity leading to a lower activation energy barrier. Remarkably, transmetalation is mainly controlled by a single orbital – the gold dx2−y2 orbital. This orbital also has a profound influence on the reactivity of the oxidative addition step. In this way, the fundamental mechanistic basis of divergent outcomes in reactions of aryl gold(I) complexes with PhICl2 was established and these observations are reconciled from first principles. The theoretical model developed in this study provides a conceptual framework for anticipating the outcomes of reactions involving [(aryl)Au(PR3)] with PhICl2, thereby establishing a solid foundation for further advancements in this field. [ABSTRACT FROM AUTHOR]

Among porous organic polymers (POPs), azo‐linked POPs represent a crucial class of materials, making them the focus of numerous catalytic systems proposed for their synthesis. However, the synthetic process is limited to metal‐catalyzed, high‐temperature, and liquid‐phase reactions. In this study, we employ mechanochemical oxidative metal‐free systems to encompass various syntheses of azo‐based polymers. Drawing inspiration from the "rule of six" principle (six or more carbons on an azide group render the organic compound relatively safe), an azo compound featuring significant steric hindrance is obtained using the hypervalent iodine oxidation strategy. Furthermore, during the polymerization process, steric hindrance is enhanced in monomers to effectively prevent explosions resulting from direct contact between hypervalent iodine oxidants and primary amines. Indeed, this approach provides a facile and innovative solid‐phase synthesis method for synthesizing azo‐based materials. [ABSTRACT FROM AUTHOR]

Despite the remarkable advances in the research field of asymmetric catalytic oxidation reactions via hypervalent iodines with simple procedures, high level of efficiency and stereoselectivity and the development of their highly scalable, environmentally benign, and sustainable protocols under the greener organocatalysis paradigm for further industrial translations remains a long-standing challenge in synthetic organic chemistry and process engineering over the past few decades. Herein, we design and synthesize a new library of conformationally flexible and recyclable aryl iodine catalysts by utilization of (i) industrial waste (chloramphenicol base) as the scaffold and (ii) inexpensive amino acid residue (threonine) as the chiral source. Our chiral aryl iodine(III) catalysts bearing H-bond donors and a tunable chiral pocket have been successfully applied in diverse, robust asymmetric oxidative transformations, e.g., dearomatization, spirolactonization, direct C(sp2)–H/C(sp3)–H cross coupling, and fluoridation. Our processes feature a column isolation-free approach, easy-handling operation, and upscaling synthesis with the catalysts being facilely recycled, in particular via precipitation. [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]

Geminal‐difluoroalkanes featuring intriguing steric and electronic properties are of great significance in medicinal chemistry, and great progresses have been achieved for their synthesis. In recent years, iodine(III) reagent‐mediated migratory gem‐difluorination of alkenes has proved to be an efficient and powerful strategy to access to diverse gem‐difluoroalkanes, especially those bearing a readily transformable functionality (TF), which are important for rapid assembly of complex gem‐difluorinated molecules in a modular and diverse manner. In this review, we systematically summarize the recent development of iodine(III)‐mediated migratory gem‐difluorination reactions for the synthesis of gem‐difluoroalkanes bearing a synthetically versatile TF at the β position. The reaction mechanism and the utilities of the products are also discussed. This review is presented and grouped basically according to the types of transformable functionalities within the products. [ABSTRACT FROM AUTHOR]

Phase change memory (PCM) and ovonic threshold switching (OTS) materials using chalcogenide glass are essential elements in advanced 3D memory chips. The mid‐gap states, induced by the disorder and defects in the glass, are the physical mechanisms of the electrical switching behavior, while the origin of these trap states is still under debate and the medium‐range clusters that break the global octet rule, such as over‐coordinated atoms, are known to be responsible in various glass. Here, it is discovered that a large fraction of over‐coordinated clusters fails to generate mid‐gap states, which are probably caused by hypervalent bonding, a multi‐centered covalent bond participated by delocalized lone‐pair electrons. This is confirmed by the pressure‐driven simulations of amorphous GeSe models, in which it is found that octahedral motifs and hypervalent bonds prevent the over‐coordinated medium‐range clusters from providing excessive electrons. In practical applications, compatible dopants can be used to change the number of hypervalent bonds, thus controlling the number of mid‐gap states and consequently the performance of PCM and OTS materials. These results reveal the origin of mid‐gap states in chalcogenide glasses, enabling extensive control in the development of pioneering electrical switching materials. [ABSTRACT FROM AUTHOR]

Direct C−H bond oxygenation is a strong and useful tool for the construction of oxygen functional groups. After Chen and White's pioneering works, various non‐heme‐type iron and manganese complexes were introduced, leading to strong development in this area. However, for this method to become a truly useful tool for synthetic organic chemistry, it is necessary to make further efforts to improve site‐selectivity, and catalyst durability. Recently, we found that non‐heme‐type ruthenium complex cis‐1 presents efficient catalysis in C(sp3)−H oxygenation under acidic conditions. cis‐1‐catalysed C−H oxygenation can oxidize various substrates including highly complex natural compounds using hypervalent iodine reagents as a terminal oxidant. Moreover, the catalyst system can use almost stoichiometric water molecules as the oxygen source through reversible hydrolysis of PhI(OCOR)2. It is a strong tool for producing isotopic‐oxygen‐labelled compounds. Moreover, the environmentally friendly hydrogen peroxide can be used as a terminal oxidant under acidic conditions. [ABSTRACT FROM AUTHOR]

Presented herein is an approach for the synthesis of highly substituted tricyclic benzopyranoisoxazoles from the corresponding aldoximes via an intramolecular nitrile oxide cycloaddition (INOC) reaction using a hypervalent iodine reagent (Diacetoxyiodo)benzene (PIDA/DIB/(PhI(OAc)2) as the single inexpensive oxidizing agent. The key step involved in this reaction is a sequential intramolecular C−C and C−O bond formation. A variety of benzopyranoisoxazoles were constructed in moderate to high yields. In addition, some of the benzopyranoisoxazoles were converted to 4H‐chromeno[4,3‐c]isoxazol‐4‐ones via allylic oxidation using CrO3 as an oxidant. [ABSTRACT FROM AUTHOR]

[45][46][47] Herein, we report a visible-light-induced C(3) difluoroalkylation of quinoxalin-2(1 I H i )-ones B 1 b with these difluoroiodane(III) reagents under catalyst-free conditions (Scheme 1, equation 7). The readily accessible reagents and the mild reaction conditions make this reaction an alternative and practical strategy for the synthesis of C3-difluoroalkylated quinoxalin-2(1 I H i )-ones. Keywords: difluoroalkylation; quinoxalinones; hypervalent iodine reagents; photocatalysis; catalyst-free reaction EN difluoroalkylation quinoxalinones hypervalent iodine reagents photocatalysis catalyst-free reaction 2037 2041 5 10/09/23 20231024 NES 231024 Graph Quinoxalin-2(1 I H i )-ones have been recognized as a privileged class of structural motifs existing in various bioactive natural products and pharmaceutical compounds. Difluoroalkylation, quinoxalinones, hypervalent iodine reagents, photocatalysis, catalyst-free reaction. [Extracted from the article]

An introduction is presented in which the editor discusses articles in the issue on topics including "Polyrotaxane-Based Functional Materials Enabled by Molecular Mobility and Conformational Transition", and "AIE Star Polymer with Enhanced Co-Delivery of Drug and Gene for Synergistic Pest Control".

The tetrel bond between PhXF2Y(TF3) (T = C and Si; X = Cl, Br, and I; Y = F and Cl) and the electron donor MCN (M = Li and Na) was investigated at the M06-2X/aug-cc-pVDZ level of theory. As the electronegativity of the halogen atom X increases, the strength of the tetrel bond also increases, but as the electronegativity of the halogen atom Y increases, the strength of the tetrel bond decreases. The magnitude of the interaction energy in most –CF3 complexes was found to be less than 10 kcal/mol, but to exceed 11 kcal/mol for PhClF2Cl(CF3)⋯NCNa. The tetrel bond is greatly enhanced when the –SiF3 group interacts with LiCN or NaCN, with the largest interaction energy approaching 100 kcal/mol and displaying a covalent Si⋯N interaction. Along with this enhancement, the Si⋯N distance was found to be less than the X–Si bond length, the –SiF3 group to be closer to the N atom, and in most –SiF3 systems, the X–Si–F angle to be less than 90°; the –SiF3 group therefore undergoes inversion and complete transfer in some systems. [ABSTRACT FROM AUTHOR]

Iodine and its hypervalent derivatives have emerged as versatile and environmentally friendly oxidative reagents in organic synthesis, offering efficient ways to form new bonds. However, the use of hypervalent iodine reagents is challenging, as they are unstable, potentially explosive, and costly. Therefore, hypoiodite species derived from onium iodites using safe and inexpensive oxidants are considered more promising for facilitating oxidative transformations. Nevertheless, applications of such catalytic systems are still limited in scope, especially for asymmetric reactions. In this concept paper, we described recent progress in chiral hypoiodite‐catalyzed enantioselective oxidative bond‐forming reactions, focusing on carbon–oxygen, carbon–nitrogen, and carbon–carbon bond formation reactions using ammonium and guanidinium salts as onium iodites. [ABSTRACT FROM AUTHOR]

Below we present the results of these investigations organized by aryl iodide structure as follows: 1) 4-Substituted aryl iodides, 2) 2- and 3-substituted aryl iodides, 3) 2-substituted 4-iodoanisole derivatives, 4) 2-substituted iodoveratrole derivatives, and 5) additional miscellaneous electron-rich aryl iodides. E SB p/2 sb values are presented for all aryl iodides and I SB p sb values (in blue in the figures) are presented only for those aryl iodides that display quasireversible electrochemistry. Keywords: hypervalent iodine; electrochemistry; linear free-energy relationships; sustainable catalysis; oxidation EN hypervalent iodine electrochemistry linear free-energy relationships sustainable catalysis oxidation 3019 3025 7 08/31/23 20230915 NES 230915 Graph Aryl iodide electrocatalysis provides a conceptual platform to combine the inherent sustainability of electrochemical oxidation with the mechanistic diversity available to hypervalent iodine-mediated transformations. [4] As a result, the application of aryl iodide electrochemistry is often limited to ex-cell applications in which anodic aryl iodide oxidation is temporally separated from substrate functionalization, which prevents undesired side reactions but obviates the potential for electrocatalysis. [Extracted from the article]

The functionalization of unactivated substrates through the combination of copper catalysts and hypervalent iodine reagents represents a versatile tool in organic synthesis to access various classes of compounds. The hypervalent iodine derivatives can be used simply as oxidizing agents to regenerate the catalytic species or they can associate the functionalization of the starting material. In this review, special attention will be paid to methodologies which provide the introduction of nucleophiles into the reagent by use of suitable benziodoxol(on)es or iodonium salts. Many reactions concern C- and N-arylations, but may also involve formation of different carbon–carbon and carbon–nitrogen bonds, carbon–oxygen as well as carbon–halogen and carbon–phosphorus bonds. [ABSTRACT FROM AUTHOR]

The isoperfluoropropyl group (i-C3F7) is an emerging motif in pharmaceuticals, agrichemicals and functional materials. However, isoperfluoropropylated compounds remain largely underexplored, presumably due to the lack of efficient access to these compounds. Herein, we disclose the practical and efficient isoperfluoropropylation of aromatic C-H bonds through the invention of a hypervalent-iodine-based reagent-PFPI reagent, that proceeds via a Ag-X coupling process. The activation of the PFPI reagent without any catalysts or additives was demonstrated in the synthesis of isoperfluoropropylated electron-rich heterocycles, while its activity under photoredox catalysis was shown in the synthesis of isoperfluoropropylated non-activated arenes. Detailed mechanistic experiments and DFT calculations revealed a SET-induced concerted mechanistic pathway in the photoredox reactions. In addition, the unique conformation of i-C3F7 in products, that involved intramolecular hydrogen bond was investigated by X-ray single-crystal diffraction and variable-temperature NMR experiments. The isoperfluoropropyl group (i-C3F7) is an analogue of the trifluoromethyl group (CF3) featuring a stronger electron-withdrawing effect and more steric hindrance, giving it a unique role in synthetic chemistry, however, direct isoperfluoropropylation remains challenging. Here, the authors develop a highly reactive electrophilic hypervalent-iodine based i-C3F7 reagent and demonstrate its use for the efficient isoperfluoropropylation of aromatic C–H bonds. [ABSTRACT FROM AUTHOR]

Herein, we report a novel strategy for the modification of peptides based on the introduction of highly reactive hypervalent iodine reagents—ethynylbenziodoxolones (EBXs)—onto peptides. These peptide‐EBXs can be readily accessed, by both solution‐ and solid‐phase peptide synthesis (SPPS). They can be used to couple the peptide to other peptides or a protein through reaction with Cys, leading to thioalkynes in organic solvents and hypervalent iodine adducts in water buffer. Furthermore, a photocatalytic decarboxylative coupling to the C‐terminus of peptides was developed using an organic dye and was also successful in an intramolecular fashion, leading to macrocyclic peptides with unprecedented crosslinking. A rigid linear aryl alkyne linker was essential to achieve high affinity for Keap1 at the Nrf2 binding site with potential protein‐protein interaction inhibition. [ABSTRACT FROM AUTHOR]

The clean and facile electrochemical synthesis of hypervalent iodine reagents is a fast growing field. In the past 5 years, a diverse number of reaction types have been established, from fluorinations, oxidative cyclizations, C−N and C−H couplings and oxidations. Electrochemistry is beneficial in terms of sustainability as the requirement for chemical oxidants is eliminated. This contributes to cleaner processes with limited by‐product waste. Often, the purification of iodine(III) compounds is simple, since electrolysis is performed in the absence stoichiometric oxidants. Significant breakthroughs have been made recently, including the first asymmetric application, electrocatalytic applications, and even the synthesis of bromine(III) reagents using similar methodologies. [ABSTRACT FROM AUTHOR]

Herein, we report the α−C−H acyloxylation of sulfides and disulfides enabled by hypervalent iodine(III) reagents via photoredox catalysis. The methoxylbenziodoxole derivatives serve as the hydrogen atom transfer agent, the mild oxidant, and the acyloxylation source in the reaction. External nucleophiles can also be introduced to the α−C−H of sulfides. The reaction applies to various aryl and alkyl sulfides including methionine peptide derivatives. Disulfides are applicable for the first time with excellent chemoselectivity and functional group compatibility. [ABSTRACT FROM AUTHOR]

Hypervalent iodine compounds have found broad application in modern organic chemistry as reagents and catalysts. Cyclic hypervalent iodine reagents based on the benziodoxole heterocyclic system have higher stability compared to their acyclic analogues, which makes possible the preparation and safe handling of the reagents with special ligands such as azido, cyano, and trifluoromethyl groups. Numerous iodine‐substituted benziodoxole derivatives have been prepared and utilized as reagents for transfer of the substituent on hypervalent iodine to organic substrate. Reactions of these reagents with organic substrates can be performed under metal‐free conditions, in the presence of transition metal catalysts, or using photocatalysts under photoirradiation conditions. In this review, we focus on the most recent synthetic applications of cyclic hypervalent iodine(III) reagents with the following ligands: N3, NHR, CN, CF3, SCF3, OR, OAc, ONO2, and C(=N2)CO2R. The review covers literature published mainly in the last 5 years. [ABSTRACT FROM AUTHOR]

Diacetoxyiodobenzene (PhI(OAc)2), commonly referred to as DAIB or phenyliodine(III) diacetate (PIDA), is one of the most frequently used hypervalent iodines employed as an oxidizing agent in organic chemistry. In this review, PIDA is highlighted exclusively in relation to its applications in organic synthesis involving heterocyclic ring formations and is critically and in‐depth examined from the summer of 2015 to the present with a specific focus on the mechanistic pathway. [ABSTRACT FROM AUTHOR]

The quantitative Lewis acidity of N‐heterocyclic iod(az)olium salts is helpful for their further application in organic chemistry. The acidity scales of different N‐Heterocyclic iodonium salts (NHISs) in acetonitrile are investigated using Density functional theory (DFT) studies. There are a total of 121N‐Heterocyclic iodonium salts that have been designed by combining N‐heterocyclic and iodonium salt structures in this research. Theoretical calculations systematically established the 31P NMR chemical shifts of NHISs, and the relative Lewis acidity scale was derived. The Lewis acidity trend is analyzed and explained by the natural population analysis (NPA) charges, molecular electrostatic potential, and the interaction between the iodonium center and the N‐heterocyclic substituents. This study is expected to provide a practical quantitative theoretical scale for the understanding and design of hypervalent iodine(III) reagents with versatile Lewis acidity. [ABSTRACT FROM AUTHOR]

A catalytic enantioselective α‐azidation reaction of β‐ketoesters with an azidated hypervalent iodine reagent was achieved by using an (R)‐BINOL‐derived chiral tin dibromide possessing 4‐t‐butylphenyl groups at the 3‐ and 3'‐positions as the chiral precatalyst in the presence of sodium ethoxide and ethanol. Optically active α‐azido‐β‐ketoesters having a chiral tertiary carbon were obtained in moderate to high yields under the influence of the chiral tin diethoxide generated in situ. [ABSTRACT FROM AUTHOR]

A convenient and efficient metal‐free oxidative [3+2] cycloaddition reaction of N‐arylmaleimides with nitrile oxides generated in situ from the corresponding aldoximes using diacetoxyiodobenzene (DIB) as hypervalent iodine reagent under mild conditions has been established. The one‐pot oxidative cycloaddition afforded corresponding bioinspired bicyclic isoxazole/pyrrolo‐isoxazole derivatives in up to 91 % yield at room temperature. To demonstrate the efficacy of this methodology, the reaction was scaled up to the gram‐scale showing synthetic potential in industrial application. The one‐pot fashion makes the strategy highly time‐economic, atom‐economic and minimizes chemical waste by circumventing several purification steps. [ABSTRACT FROM AUTHOR]

Hypervalent iodine reagents have the ability of inverting the polarity of functional groups bound to iodine, a reactivity known as umpolung. This reactivity makes hypervalent iodine compounds highly attractive for the creation of electrophilic synthons of known nucleophiles, resulting in novel synthetic disconnections and the formation of new Nu(nucleophile)−N bond. Electrophilic sources of nitrogen‐based groups have been known for many decades and are of great synthetic importance. Traditionally, these reagents are limited to few examples. With the use of hypervalent iodine, the transfer of a wide diversity of nitrogen sources became a possibility. This review compiles the latest reported examples of hypervalent iodine reagents capable of electrophilic transfer of nitrogen‐based groups. It showcases the preparation of such reagents, their synthetic utility, and reaction mechanisms involving these group transfer reagents. [ABSTRACT FROM AUTHOR]

The chemistry of hypervalent iodine reagents has now become quite valuable due to the reactivity of these compounds under mild reaction conditions and their resemblance in chemical properties to transition metals. The environmentally friendly nature of these reagents makes them suitable for Green Chemistry. Reagents with a dual nature, such as iodine(III) reagents, are capable electrophiles, while iodine(V) reagents are known for their strong oxidant behavior. Various iodine(V) reagents including IBX and DMP have been used as oxidants in organic synthesis either in stoichiometric or in catalytic amounts. In this review article, we describe various oxidation reactions induced by iodine(V) reagents reported in the past decade. [ABSTRACT FROM AUTHOR]

Hypervalent iodine (III and V) compounds exhibit positional isomerization through pseudorotation or twisting; the latter have been invoked for the stability as well as the reactivity of λ3‐ and λ5‐iodanes. By judicious exploitation of sterics, the twisting process in iodanes can be facilitated to promote reactivity. For example, ortho‐substitution in λ3‐ and λ5‐iodanes accelerates α‐tosyloxylation of ketones and oxidation of alcohols. The enhancement of reactivity arises from sterically‐induced non‐planarity and the resultant weakening of the 3c–4e bonds involving the hypervalent iodine atom. The ortho‐substitution constitutes an important strategy to maneuver reactivity, control selectivity, and develop new catalysts, including chiral, for diverse reactions. This review entails coverage of the literature developments in regard to the effect of substituents and twisting/pseudorotation on the stability as well as the reactivity of hypervalent λ3‐ and λ5‐iodanes, and the application of the latter for synthetic transformations. [ABSTRACT FROM AUTHOR]