Reaction Of Iodine Research Articles

Hypervalent iodine reactions utilized in carbon-carbon bond formations.

Advances in hypervalent iodine chemistry have put the field on the precipice of a second golden age; the first being pioneered in the 1990s. During that period, C-C bond forming reactions would be published but rarely with the intended goal of developing a C-C bond forming methodology. More recently, the development of hypervalent iodine-guided electrophilic substitution, arylations using hypervalent iodine, and photoredox reactions with hypervalent iodine have shown great progress in the area of C-C bond formation.

An intramolecular C(sp3)-H imination using PhI-mCPBA.

Herein, a highly exothermic primary amine-polyvalent iodine reaction has been used successfully for selective functionalization of acidic C(sp3)-H groups for a dehydrogenative C-H imination reaction by 4H elimination. Overall, C(sp3)-H imination at 1,5 distances was readily done via organocatalysis using PhI (10 mol%)-mCPBA under ambient conditions.

Metal-Free Synthesis of Functionalized Tetrasubstituted Alkenes by Three-Component Reaction of Alkynes, Iodine, and Sodium Sulfinates.

An operationally simple, efficient, and metal-/peroxide-free three-component reaction of alkynes, iodine, and sodium sulfinates has been developed for the construction of highly functionalized tetrasubstituted alkenes. Iodo- and sulfonyl-containing tetrasubstituted alkenes, such as vinyl ketones, allylic alcohols, and conjugated enynes, could be obtained regio- and stereoselectively in up to 96% yield.

Structural and Electrical Properties of Nb3I8 Layered Crystal

Centimeter‐size single‐crystalline Nb3I8, a new family of two‐dimensional materials, is first synthesized by a vapor transport reaction of niobium and iodine. Through the mechanical exfoliation method, the bulk Nb3I8 crystal is cleaved to monolayer and multi‐layered flakes. It is confirmed to consist of numerous monolayers of Nb3I8 bonded by weak van der Waals interaction. By utilizing atomic force microscopy (AFM) and scanning Kelvin probe microscopy (SKPM), the information on structure and electrical properties is obtained at the same time. The analysis results show that the surface potential difference and the work function tend to increase as the Nb3I8 becomes thicker due to the interlayer screening effect. The results for the work function variation dependence on thickness are useful for selecting a suitable metal electrode for future Nb3I8‐based nano‐devices which can have a significant impact on performance.

SHELLFISH ALLERGY & RISK FOR IODINATED RADIOCONTRAST REACTIONS: A PERPETUATED MYTH

Introduction We assessed whether patients are still asked about prior reactions to shellfish during screening for radiocontrast media (RCM) administration, if providers are still misinformed about the relationship between shellfish allergy, iodine reactions, and reactions to RCM, and if subsequent management is altered. Methods From 2016-2018, 191 providers responded to a 14-question survey (Survey Monkey) sent to cardiologists, radiologists and anesthesiologists throughout the United States, representing a mix of academic, community hospital, and private practice settings. Three main questions were: (1) Before procedures, do you ask about reactions to shellfish; (2) Why do you ask this; (3) If a patient reports a history of adverse reaction to shellfish, what additional precautions are taken. Results 159 responders completed the survey. 33% of providers asked about reactions to shellfish when screening patients before procedures. 48% of providers responded they do this due to: “prior reactions to shellfish may increase the risk for iodine reactions”. Providers reported that management could be impacted based on patient reports of a prior shellfish reaction (see Figure) including: giving premedication, choosing a low iodinated contrast, avoiding the use of povidone-iodine, or withholding contrast altogether. Conclusions Despite clear evidence that shellfish allergy is unrelated to risk for RCM reactions, its pre-procedure screening is still performed in the United States. Patient management is unnecessarily impacted based on the results of such screening and a medical myth is subsequently perpetuated. As allergy care providers, we must educate those involved in RCM screening to close a knowledge gap that continues to persist. Figure. If a patient reports a history of reacting to shellfish, what additional precautions are taken? (Check all that apply)

Valence band offsets for CuI on (-201) bulk Ga2O3 and epitaxial (010) (Al0.14Ga0.86)2O3

Thin films of copper iodide (CuI) were grown on (-201) bulk Ga2O3 and (010) epitaxial (Al0.14Ga0.86)2O3 using a copper film iodination reaction method. The valence band offsets for these heterostructures were measured by X-ray photoelectron spectroscopy (XPS). High resolution XPS data of the O 1s peak and onset of elastic losses were used to establish the (Al0.14Ga0.86)2O3 bandgap to be 5.0 ± 0.30 eV. The valence band offsets were −0.25 eV ± 0.07 eV and 0.05 ± 0.02 eV for CuI on Ga2O3 or (Al0.14Ga0.86)2O3, respectively. The respective conduction band offsets were 1.25 ± 0.25 eV for Ga2O3 and 1.85 ± 0.35 eV for (Al0.14Ga0.86)2O3. Thus, there is a transition from type-II to type-I alignment as Al is added to β-Ga2O3. The low valence band offsets are ideal for hole transport across the heterointerfaces.

Iodine(III)-Enabled Distal C-H Functionalization of Biarylsulfonanilides.

Here we report a metal-free C-N coupling reaction for carbazole synthesis by distal (- meta) C-H bond functionalization. Nitrenium ion, a potential synthetic intermediate, was generated in situ from reactions of iodine(III) reagents and biarylsulfonanilides. Following, nitrenium ions were used for intramolecular dehydrogenative C-N coupling reactions via 1,2-alkyl (methyl or ethyl) migration by the expense of C-H bond functionalization at the distal position toward synthesis of 1,2,4-trialkyl-substituted carbazoles. The iodine(III) condition was either maintained by using a stoichiometric amount of phenyliodine diacetate (PIDA) or in-situ generated from iodobenzene (PhI)- meta-chloroperbenzoic acid ( mCPBA) combination.

Bridgehead-Modified NBEs: A Solution to ortho-Constraint in Catellani-type Reactions

Recent work published by Dong and co-workers in Nature Chemistry addresses the long-standing "ortho-constraint" in Catellani-type reactions by employing a new class of bridgehead-modified norbornenes as the mediator. The previously unsuccessful ortho-unsubstituted aryl iodides are well tolerated in current reaction systems in that they deliver a wide range of mono ortho-C‒H-functionalized products with high efficiency.

Tuning Lewis Acidity of Metal-Organic Frameworks via Perfluorination of Bridging Ligands: Spectroscopic, Theoretical, and Catalytic Studies.

The Lewis acidity of metal-organic frameworks (MOFs) has attracted much research interest in recent years. We report here the development of two quantitative methods for determining the Lewis acidity of MOFs-based on electron paramagnetic resonance (EPR) spectroscopy of MOF-bound superoxide (O2•-) and fluorescence spectroscopy of MOF-bound N-methylacridone (NMA)-and a simple strategy that significantly enhances MOF Lewis acidity through ligand perfluorination. Two new perfluorinated MOFs, Zr6-fBDC and Zr6-fBPDC, where H2fBDC is 2,3,5,6-tetrafluoro-1,4-benzenedicarboxylic acid and H2fBPDC is 2,2',3,3',5,5',6,6'-octafluoro-4,4'-biphenyldicarboxylic acid, were shown to be significantly more Lewis acidic than nonsubstituted UiO-66 and UiO-67 as well as the nitrated MOFs Zr6-BDC-NO2 and Zr6-BPDC-(NO2)2. Zr6-fBDC was shown to be a highly active single-site solid Lewis acid catalyst for Diels-Alder and arene C-H iodination reactions. Thus, this work establishes the important role of ligand perfluorination in enhancing MOF Lewis acidity and the potential of designing highly Lewis acidic MOFs for fine chemical synthesis.

Strategies, Setbacks, and Successes in the Synthesis of (-)-Spiroleucettadine.

Various strategies toward the synthesis of the marine natural product (-)-spiroleucettadine are described. In the original strategy, a biomimetic inspired oxidation of a 2-imidazoline scaffold uncovered unexpected reactivity, where benzylic oxidation followed by a Baeyer-Villiger reaction was observed. The second generation approach examined oxidative dearomatization of the phenol ring system first, where a competing spirocyclization process was uncovered. Efforts to forge the scaffold via a carbocation mediated benzyl migration were unsuccessful. Highlights of the successful synthesis include two consecutive hypervalent iodine reactions: the first formed the spirocyclic center and the second facilitated installation of an acetate group at the C-5 position to allow for subsequent introduction of the methyl amine side chain.

Weinreb Amide Directed Versatile C-H Bond Functionalization under (η5 -Pentamethylcyclopentadienyl)cobalt(III) Catalysis.

The (η5 -pentamethylcyclopentadienyl)cobalt(III) (Cp*CoIII )-catalyzed C-H bond functionalization of aromatic, heteroaromatic, and α,β-unsaturated Weinreb amides was explored. C-H allylation reactions with the use of allyl carbonate and a perfluoroalkene, oxidative alkenylation reactions with the use of ethyl acrylate, iodination reactions with the use of N-iodosuccinimide, and amidation reactions with the use of dioxazolones were catalyzed by Cp*Co(CO)I2 in the presence of a cationic Ag salt and AgOAc to afford various synthetically useful building blocks. Mechanistic studies of the C-H allylation disclosed that the C-H activation step was rate determining and virtually irreversible.

Two-Step Continuous Synthesis of Dicarbonyl Indoles via I2/DMSO-Promoted Oxidative Coupling: A Green and Practical Approach to Valuable Diketones from Aryl Acetaldehydes

A green and practical method for the synthesis of C-3 dicarbonyl indoles from aryl acetaldehydes and indoles was developed under I2/DMSO conditions, employing an assembled two-step continuous flow system. Moderate to good yields of dicarbonyl indole derivatives have been achieved by consuming a lower dosage of iodine and shorter reaction time without amine catalysts added, which presents major advantages over reactions in a traditional batch. Moreover, this method was also compatible with the synthesis of α-ketoamides and α-ketoesters by adjusting the reaction parameters of a continuous flow system, which indicates its good universality. And a possible mechanism was proposed based on DMSO18 isotopic labeled experiments.

Formation of CH3I in a NaI and methyl alkyl ketone solution under gamma irradiation conditions

We investigated the effects of concentrations of NaI and methyl alkyl ketone on the formation of methyl iodide under gamma irradiation conditions. Without irradiation, the formation of methyl iodide does not occur. For the formation of methyl iodide, the solution pH should be brought to lower than 6 by radiolytic decomposition of ketones and air. At a pH below 6, the iodide was oxidized into iodine, allowing for the formation of CH3I from the reaction of iodine and the CH3 radical. When the concentrations of NaI and methyl alkyl ketone were similar, the concentration of methyl iodide was generally at its highest, and as the gamma dose increased, the concentration of methyl iodide increased.

Iodine Activation of Alcohols: A Computational Study

A DFT study aimed at unravelling the origin of catalytic activity of iodine in reaction with alcohols is presented. Computed free energies for generation of the O–I complexes from the separated reactants are around 3 kcal/mol and solvation increases endoergicity by ca. 1 kcal/mol. Calculations suggest that halogen bond formation between I2 and alcohols does not lead to strong activation of the hydroxyl as a leaving group, although solvent has a notable effect in lowering endoergicity for carbocation formation. Model tertiary alcohols exhibited β-proton abstraction following breaking of the C–O bond, while model secondary and primary alcohols experienced an earlier β-proton abstraction, synchronic with the C–O bond cleavage. Consistent with computed natural bond orbital charges, benzylic and propargylic alcohols underwent iodide anion quenching at the para position of phenyl and C-3, respectively.

A Convenient One-Pot Synthesis of 1-Aryl-Substituted 4-Iodopyrazol-3-Ols via Aromatisation and Oxidative Iodination Reactions

A convenient and economical one-pot synthesis of a series of new 1-aryl-substituted 4-iodopyrazole-3-ols from easily available pyrazolidin-3-ones in the presence of sodium iodide, 30% solution of hydrogen peroxide and a catalytic amount of sulfuric acid in dichloromethane via aromatisation and oxidative iodination reactions are described. This protocol has the advantages of high atom economy, cost-effectiveness, short reaction time and environmental friendliness.

Copper-Catalyzed Decarboxylative Iodination Reaction in the Gas Phase

Copper-Catalyzed Decarboxylative Iodination Reaction in the Gas Phase

A convenient one-pot synthesis of 1-aryl-substituted 4-iodopyrazole-3-ols via aromatization and oxidative iodination reactions_ESI

A convenient one-pot synthesis of 1-aryl-substituted 4-iodopyrazole-3-ols <i>via</i> aromatization and oxidative iodination reactions_ESI

In situ chemical vapor deposition of metals on vapor-grown carbon fibers and fabrication of aluminum-matrix composites reinforced by coated fibers

Aluminum, nickel, silicon, and titanium were deposited onto the surfaces of vapor-grown carbon fibers (VGCFs) using a simple and cost-effective in situ chemical vapor deposition method. This process began with the in situ reaction of metal powders and iodine in heated quartz tubes, leading to the formation of metallic iodide vapors. Aluminum was deposited by annealing at 500 °C, forming almost homogeneous metallic aluminum layers on VGCFs. Aluminum-matrix composites reinforced by aluminum-coated VGCFs were fabricated by powder metallurgy. The tensile strength of these composites was improved by the aluminum-coating treatment. Nickel was deposited by annealing at 600 °C. The coating layer consisted of grains smaller than 5 nm. Molten aluminum was dropped on sheets comprising nickel-coated VGCFs, and the contact angle was measured; the wettability was found to be clearly improved. Composites containing nickel-coated VGCFs were fabricated via hot extrusion of a mixture of Al–7Si alloy and VGCFs at semisolid temperature. Vickers microhardness values of the composites were improved by nickel-coating treatment because of improved interaction of the aluminum matrix and VGCFs at the interface. A metallic silicon-coating layer was formed by annealing at 1100 °C. For titanium coating, the reaction of VGCFs with titanium and conversion of the VGCF surface into titanium carbide was confirmed. In the case of titanium, metallic titanium could be deposited without the use of iodine.

Spectrophotometric Micro Determination of Tretinoin, Isotretinoin using Iodine and Tazarotene micro determination via Reaction with Rose-Bengal Reagent

THE reactions of Iodine or Rose-Bengal (Rbng) reagents with three of retinoid drugs Tretinoin (Tret), Isotretinoin (Itret) and Tazarotene (Taz) had been studied for the development of simple, rapid, sensitive spectrophotometric methods for micro-determining of these drugs in pure and in their pharmaceutical formulation. These methods are based on the formation of reaction product between the drugs and iodine or rose -bengal reagent. The spectra of the formed reaction products were measured at selected proper conditions of time, temperature, pH and selected wavelength. The analytical parameters such as standard deviation (SD), relative standard deviation (RSD), Sandell’s sensitivity (S), LOQ and LOD were calculated in order to check accuracy, sensitivity and precision of the given procedures. The values of SD = 0.1312 - 1.100, RSD = 0.5556 - 1.946 %, S = 0.0229 – 0.0508 μg cm-2, LOQ = 13.17 – 17.45 μg mL-1, LOD = 4.347 – 5.757 μg mL-1 obtained of these parameters refer to the accuracy and sensitivity of the suggested procedures and can be applied for analyses of these drugs in their pharmaceutical formulations. Beer's law was valid in the range 9.041 – 29.71, 35.75 – 119.6 and 10.48 – 71.11 μg mL-1 with recovery of (97.84 - 102.8 %), (98.67 - 101.8 %), (98.32 - 102.0 %) for Tretinoin, Isotretinoin and Tazarotene respectively, The importance of this research stems from applications of these retinoid derivatives in skin improvements. They are always used as creams and found to be effective for photo-damage and for protection from skin irritation. Therefore, the proposed methods had been applied successfully for the analysis of the studied drugs in pure forms and pharmaceutical formulations. The results obtained were found to be in good agreement with those obtained by official methods. This evaluation had been done by F- and t- tests

Enantiospecific Semisynthesis of Puupehedione-Type Marine Natural Products.

An enantiospecific semisynthesis of puupehedione was achieved from sclareolide in only 7 steps with an overall yield of 25%. The key drimanal trimethoxystyrene skeleton was constructed by the palladium-catalyzed cross-coupling reaction of an aryl iodine and a drimanal hydrazone. An in situ CAN-oxidation/intramolecular oxa-Stork-Danheiser transposition tandem reaction was used as a powerful tool to install concurrently the C and D rings of puupehedione in a one-pot fashion. Its applicability was also showcased by the semisynthesis of puupehenone and puupehenol.