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A direct α‐alkenylation of nitrile compounds was realized with a palladium complex. This method exhibited excellent tolerance toward a variety of α‐aryl alkyl nitriles and vinyl bromides, leading to the formation of a series of α‐quaternary nitriles containing vinyl groups. Further manipulations of the obtained products were demonstrated, highlighting the potential synthetic utility of this method. [ABSTRACT FROM AUTHOR]

The process of Infrared Multiphoton Dissociation (IRMPD) was studied in a mixture of vinyl bromide/chlorodifluoromethane (VBr, C2H3Br/CF2HCl) using single and double infrared pulsed transverse excitations atmospheric CO2 laser beams. The dissociation of VBr was investigated using FTIR, and the product composition was analysed, and various dissociation routes were proposed. The study found that the VBr molecules were more heavily dissociated when exposed to the CF2HCl environment than without it. By using a time-resolved LIF, the kinetics reactions with CF2HCl were explored under pseudo-first-order conditions, and the quenching rate constant for the interaction between CF2HCl and C 2 d 3 Π g was published using the classical Stern–Volmer model. The impact of pulsed laser heating on the generation of C 2 a 3 Π u radicals was also observed. The decrease in the intensity of the C 2 (a 3 Π u) LIF signal was due to faster recombination of the C 2 a 3 Π u radicals, together with a decrease in V - V ′ energy transfer and the pressure oscillations produced by the effect of pulsed laser heating in the irradiated volume and the experimental conditions. [ABSTRACT FROM AUTHOR]

The Pd‐catalyzed vinylation reactions of aryl iodides using 1,2‐dibromoethane is developed for the synthesis of styrenes and stilbenes. In these reactions, vinyl bromide is generated from 1,2‐dibromoethane and then undergoes reductive cross‐coupling with aryl iodides, affording styrene products. Under slightly modified reaction conditions, styrenes can continue reacting with vinyl bromide to form E‐stilbenes, which provides a one‐pot synthetic method for stilbenes. Alcohols, including iso‐propanol and methanol, are employed as the reductant in these reductive cross‐coupling reactions. [ABSTRACT FROM AUTHOR]

This review summarizes the applications of vinyl sulfonate and vinyl acetate as green alternatives for vinyl bromide in cross-coupling reactions. In the first part, the preparation of vinyl sulfonates and their cross-coupling reactions are briefly discussed. Then, a brief review of vinyl acetate cross-coupling reactions, including cyclization reactions, the Fujiware–Moritani reaction, and transvinylation reactions are described. [ABSTRACT FROM AUTHOR]

The enantioselective reductive coupling of oxabenzonorbornadiene with vinyl bromide is developed with earth‐abundant nickel catalyst with copper as Lewis acid co‐catalyst. The asymmetric reductive coupling is applicable with a wide range of azabenzonorbornadienes and vinyl bromides under nickel/copper co‐catalytic system, affording the cis ring‐opening vinylation products in good yields with high optical purities. The present study has enabled straightforward stereoselective preparation of chiral 2‐vinyl‐tetrahydronaphthalens from vinyl halides. [ABSTRACT FROM AUTHOR]

The radical bromoallylation of alkynes, allenes, and vinylidene cyclopropanes proceeds efficiently in the presence of a radical initiator to give 2-bromo-substituted 1,4-, 1,5-, and 1,6-diene derivatives, respectively. Three-component reactions comprised of allenes, electron-deficient alkenes, and allyl bromides give 1,7-dienes in good yields. The bromoallylation of an arylalkene can override β-scission of the bromine radical from β-bromoalkyl radicals to give 5-bromoalkenes, whilst the bromoallylation of vinylcyclopropanes is accompanied by 5- exo ring closure to give 1-(bromomethyl)-2-vinylcyclopentane derivatives in good yields. All of the products contain a reactive vinyl bromide moiety, which can be readily functionalized by Pd-catalyzed cross-coupling and radical cascade reactions. 1 Introduction 2 Synthesis of 1,4-Dienes by Bromoallylation of Acetylenes 3 Synthesis of 1,5-Dienes by Bromoallylation of Allenes 4 Synthesis of 1,6-Dienes by Bromoallylation of Methylenecyclopropanes 5 Synthesis of 1,7-Dienes by Bromoallylation of Allenes and Electron-Deficient Alkenes 6 Bromoallylation of Arylalkenes and Vinylcyclopropanes 7 Conclusion [ABSTRACT FROM AUTHOR]

Herein, an efficient strategy to synthesize 2‐unsubstituted terminal 1, 3‐enynes in high yields by bimetallic Pd/Cu‐catalyzed Sonogashira coupling‐elimination reaction of iodobenzenes with 4‐bromobut‐1‐yne was reported. To our knowledge, this is the first report of 4‐bromobut‐1‐yne as an efficient 1, 3‐enynes reagent, and the method is more convenient and cost‐effective than other reported synthetic methods, which are hindered by the laborious preparation of starting materials, the high cost of bromoethene, and the inconvenient handling of gas acetylene. [ABSTRACT FROM AUTHOR]

An efficient [3 + 2] cycloaddition reaction involving vinyl acetates with tri/difluoroacetohydrazonoyl bromides has been established. This reaction provides an efficient method for synthesis of highly valuable ring-fused fluoroalkyl pyrazoles in moderate to good yields under mild reaction conditions, exhibiting remarkable regioselectivity and broad substrate scopes. The strategy further demonstrated that tri/difluoroacetohydrazonoyl bromides are effective tri/difluoromethyl building blocks for synthesis of fluoroalkyl heterocycle compounds. [Display omitted] • Tri/difluoromethyl pyrazoles were synthesized using tri/difluoromethylacetohydrazonoyl bromides as building blocks. [ABSTRACT FROM AUTHOR]

Annulation reactions of pyridine-2-sulfenyl bromide with vinyl and allyl ethers proceeded regioselectively, but with opposite regiochemistry. Reactions with vinyl ethers led to 3-organyloxy-2,3-dihydro[1,3]thiazolo[3,2-a]pyridin-4-ium bromides (91–99% yields), while allyl ethers gave 2-substituted derivatives of 2,3-dihydro[1,3]thiazolo[3,2-a]pyridin-4-ium (90–98% yields). Tricyclic condensed compounds were synthesized by reactions of pyridine-2-sulfenyl bromide with cyclic ethers (2,3-dihydrofuran, 3,4-dihydro-2H-pyran and 2,5-dihydrofuran). [ABSTRACT FROM AUTHOR]

A Grubbs II catalyst mediated ring-closing metathesis (RCM) of monobrominated dienes is reported to proceed in moderate to good yields (40–80%) where the linking chain contains five atoms, leading to carbocyclic and heterocyclic seven-membered bromoolefins. Notably, RCM to form five-, six-, or eight-membered bromoolefins was unsuccessful, with the exception of one example where RCM afforded diethyl 3-bromocyclohex-3-ene-1,1-dicarboxylate. In this case, a bromomethyl-substituted cyclohexene was obtained as a byproduct. The utility of selected bromoolefin RCM products was demonstrated through their participation in Suzuki–Miyaura reactions. Vinylic halide exchange (Br → Cl) was noted as a side reaction under RCM conditions. [ABSTRACT FROM AUTHOR]

Thiazole or 1,3-thiazole is a distinct heterocyclic compound which incorporates sulphur and nitrogen atoms. It is a vital framework present in numerous pharmacologically active compounds, be it of natural origin or of synthetic nature. Many thiazoles having antitumor and antiviral activities, originate from microbes and marine organisms. A variety of synthetic drugs, having thiazole group, like antimicrobial sulfathiazole, antibiotic penicillin, antidepressant pramipexole, antineoplastic agent bleomycin, antiretroviral drug ritonavir, histamine H2 receptor antagonist nizatidine, anti-inflammatory drug meloxicam, antifungal stilbene derivatives have been in the markets for quite some time. Hofmann and Hantzsch laid the groundwork for further development in the field of thiazole chemistry. The interaction of α-haloketones or α-halogenaldehyde and thioamide to obtain thiazoles is beautifully described by Hantzsch. Various studies have reported methods for the synthesis of the thiazoles; thioforamide, thiourea, α-thiocyanotoketones, and vinyl bromide have been extensively employed to synthesize thiazoles. The thiazoles have immense potential and this study tries to enlighten the crucial role of thiazoles for the betterment of society. The review provides different directions in the synthesis of novel thiazoles and also reveals diverse targets for augmentation in the field of designing of novel thiazoles. [ABSTRACT FROM AUTHOR]

A nickel-catalyzed cross-electrophile coupling is disclosed in which a range of vinyl bromides were utilized as electrophiles with oxalates derived from α-hydroxy carbonyls as precursors to carbonyl radical coupling partners. This method is compatible with a broad range of functional groups, providing a complementary solution for the construction of β,γ-unsaturated carbonyl compounds. [ABSTRACT FROM AUTHOR]

Even at low concentrations, poly-aromatic hydrocarbons found in soot have substantial health implications. Soot deposits have been reported and studied using FTIR and Raman spectroscopy. Using a CO2 photolysis laser, the samples were obtained via infrared multiphoton dissociation (IRMPD) of vinyl bromide (VBr, C2H3Br) molecules. The solid deposit formed in the IRMPD of VBr when a relatively high fluence of the order of 204 J.cm−2 was analyzed by FTIR, and it was discovered that the majority of its composition is aromatic and aliphatic hydrocarbons. Significant fullerene-type carbonaceous soot particles are also found, which could correspond to C60 and C70 or other carbonaceous agglomerates of a higher order; however, the disappearance of this fullerene on Raman spectra cast doubt on this explanation. Our samples' Raman spectroscopy has been compared to Tamor and Vassell's research, which may indicate that they have a lesser degree of hardness and density than these authors' results, indicating a larger hydrogen content in our samples. The optical gap has been calculated, yielding a very limited range of values ranging only between 1.0 and 1.2 eV, resulting in a crystalline size of 0.58 to 1.12 nm. [ABSTRACT FROM AUTHOR]

The 4‐exo‐dig cyclocarbopalladation of vinyl bromides substituted with a triple or double bond resulted in impressive cascade reactions leading to different compounds under Suzuki cross‐coupling conditions upon a slight modification of the starting material. When the starting compound carries a triple bond, a single cascade occurs providing a structure containing an allene, a tetrasubstituted cyclopropane, and a cyclobutene with complete stereoselectivity. When the related starting material possessing a double bond is reacted under the same conditions in the presence of various vinyl boronic esters or acids, an efficient 8π‐electrocyclization provides tricyclic systems comprised of a cyclobutene unit, as well as a cyclooctatriene. Five carbons of the latter can be selectively decorated with different substituents depending on the choice of the starting material and the boronic coupling partner. [ABSTRACT FROM AUTHOR]

An O2‐assisted, four‐component reaction has been developed to synthesize a wide range of syn‐1,3‐amino alcohols in one step. The reaction proceeds by oxygenation of vinyl magnesium bromide (component‐I) with O2 (component‐II) to give a magnesium enolate of acetaldehyde, which undergoes addition to a chiral N‐tert‐butanesulfinyl imine (component‐III) followed by a sequential addition with excess vinyl magnesium bromide (component‐IV). The approach allows diastereoselective synthesis of anti/syn‐ and syn/syn‐3‐amino‐1,5‐diols in good yields with high diastereoselectivity. The method was illustrated in an efficient, four‐step synthesis of piperidine alkaloid (−)‐2′‐epi‐ethylnorlobelol. [ABSTRACT FROM AUTHOR]

2,3-Dibromo-2-methylpropanamides with different substituents on the nitrogen atom were synthe-sized, and their transformations by the action of potassium tert-butoxide in THF were studied. 2,3-Dibromo-N-(4-methoxyphenyl)-2-methylpropanamide and 2,3-dibromo-N-(2,5-dibromo-4-methoxyphenyl)-2-methyl-propan-amide reacted with 1–2 equiv of t-BuOK to give the corresponding N-substituted 3-bromo-3-methyl- and 3-methylideneazetidin-2-ones with acceptable yields and selectivity. Increase of the amount of t-BuOK to 3–5 equiv led to significant reduction of the yield of vinyl bromides and 3-methylideneazetidin-2-ones. On the other hand, the reaction of 2,3-dibromo-N-(tert-butyl)-2-methylpropanamide with t-BuOK afforded 3-(tert-bu-toxymethyl)-1-tert-butylazetidin-2-one with a good yield and selectivity. [ABSTRACT FROM AUTHOR]

Aliphatic bromide was used as a halogenation reagent in the presence of DMSO, resulting in 2,2-diarylvinyl bromides from the corresponding 1,1-diarylethylenes. This protocol not only provides a convenient and straightforward strategy for the rapid construction of various 2,2-diarylvinyl bromides without bromine and extra oxidants, but also can improve the atom economy of Kornblum oxidative reaction. [ABSTRACT FROM AUTHOR]

An enantioselective synthetic approach for preparing manginoids and guignardones, two types of biogenetically related meroterpenoids, is reported. This bioinspired and divergent synthesis employs an oxidative 1,3‐dicarbonyl radical‐initiated cyclization and cyclodehydration of the common precursor to forge the central ring of the manginoids and guignardones, respectively, at a late stage. Key synthetic steps include silica‐gel‐promoted semipinacol rearrangement to form the 6‐oxabicyclo[3.2.1]octane skeleton and the Suzuki–Miyaura reaction of vinyl bromide to achieve fragment coupling. This synthesis protocol enables the asymmetric syntheses of four fungal meroterpenoids from commercially available materials. [ABSTRACT FROM AUTHOR]

Attosecond extreme ultraviolet (XUV) and soft x-ray sources provide powerful new tools for studying ultrafast molecular dynamics with atomic, state, and charge specificity. In this report, we employ attosecond transient absorption spectroscopy (ATAS) to follow strong-field-initiated dynamics in vinyl bromide. Probing the Br M edge allows one to assess the competing processes in neutral and ionized molecular species. Using ab initio non-adiabatic molecular dynamics, we simulate the neutral and cationic dynamics resulting from the interaction of the molecule with the strong field. Based on the dynamics results, the corresponding time-dependent XUV transient absorption spectra are calculated by applying high-level multi-reference methods. The state-resolved analysis obtained through the simulated dynamics and related spectral contributions enables a detailed and quantitative comparison with the experimental data. The main outcome of the interaction with the strong field is unambiguously the population of the first three cationic states, D1, D2, and D3. The first two show exclusively vibrational dynamics while the D3 state is characterized by an ultrafast dissociation of the molecule via C–Br bond rupture within 100 fs in 50% of the analyzed trajectories. The combination of the three simulated ionic transient absorption spectra is in excellent agreement with the experimental results. This work establishes ATAS in combination with high-level multi-reference simulations as a spectroscopic technique capable of resolving coupled non-adiabatic electronic-nuclear dynamics in photoexcited molecules with sub-femtosecond resolution. [ABSTRACT FROM AUTHOR]

Strong-field induced ionization and dissociation dynamics of vinyl bromide, CH2=CHBr, are probed using femtosecond extreme ultraviolet (XUV) transient absorption spectroscopy. Strong-field ionization is initiated with an intense femtosecond, near infrared (NIR, 775 nm) laser field. Femtosecond XUV pulses covering the photon energy range of 50-72 eV probe the subsequent dynamics by measuring the time-dependent spectroscopic features associated with transitions of the Br (3d) inner-shell electrons to vacancies in molecular and atomic valence orbitals. Spectral signatures are observed for the depletion of neutral C2H3Br, the formation of C2H3Br+ ions in their ground (X ) and first excited (à ) states, the production of C2H3Br++ ions, and the appearance of neutral Br (2P3/2) atoms by dissociative ionization. The formation of free Br (2P3/2) atoms occurs on a timescale of 330 ±150 fs. The ionic à state exhibits a time-dependent XUV absorption energy shift of ∼0.4 eV within the time window of the atomic Br formation. The yield of Br atoms correlates with the yield of parent ions in the à state as a function of NIR peak intensity. The observations suggest that a fraction of vibrationally excited C2H3Br+ (à ) ions undergoes intramolecular vibrational energy redistribution followed by the C-Br bond dissociation. The C2H3Br+ (X) products and the majority of the C2H3Br++ ions are relatively stable due to a deeper potential well and a high dissociation barrier, respectively. The results offer powerful new insights about orbital-specific electronic processes in high field ionization, coupled vibrational relaxation and dissociation dynamics, and the correlation of valence hole-state location and dissociation in polyatomic molecules, all probed simultaneously by ultrafast table-top XUV spectroscopy. [ABSTRACT FROM AUTHOR]

The transition-metal-catalyzed carboxylation of aryl and vinyl chlorides with CO2 is rarely studied, and has been achieved only with a Ni catalyst or combination of palladium and photoredox. In this work, the cobalt-catalyzed carboxylation of aryl and vinyl chlorides and bromides with CO2 has been developed. These transformations proceed under mild conditions and exhibit a broad substrate scope, affording the corresponding carboxylic acids in good to high yields. [ABSTRACT FROM AUTHOR]

The transition-metal-catalyzed carboxylation of aryl and vinyl chlorides with CO2 is rarely studied, and has been achieved only with a Ni catalyst or combination of palladium and photoredox. In this work, the cobalt-catalyzed carboxylation of aryl and vinyl chlorides and bromides with CO2 has been developed. These transformations proceed under mild conditions and exhibit a broad substrate scope, affording the corresponding carboxylic acids in good to high yields. [ABSTRACT FROM AUTHOR]

A mild and useful nickel‐catalyzed electrochemical phosphonylation of aryl and vinyl bromides is described. We show that alkyl H‐phenylphosphinates can be coupled electrochemically with functionalized aryl and vinyl bromides using very simple conditions (Fe/Ni anode, bench‐stable nickel pre‐catalyst, undivided cell, galvanostatic electrolysis) to furnish the corresponding aryl and vinyl phosphinates in satisfactory to good yields. Couplings can also be applied to heteroaromatic bromides with some limitations like increased propensity to hydro‐dehalogenation. [ABSTRACT FROM AUTHOR]

The synthesis of vinyl sulfones via silver-promoted cross-coupling of vinyl bromides with sulfonyl hydrazides was realized. Water was used as the sole solvent. Multisubstituted vinyl sulfones were easily prepared with excellent alkyl group tolerance. A mechanism involving nucleophilic attack of a sulfinate anion was proposed. [ABSTRACT FROM AUTHOR]

3‐(Hetero)aryl propenals or propenones are efficiently prepared by a Heck reaction of (hetero)aryl bromides and acrolein or vinyl ketones using Beller's CataCXium® Ptb ligand under Jeffery's and Fu's conditions. The formation of these three‐carbon building blocks is embedded into consecutive three‐ and pseudo‐four‐component syntheses of 3‐(hetero)aryl and 3,5‐diarylpyrazoles with a broad substitution pattern in moderate to excellent yield. [ABSTRACT FROM AUTHOR]

A novel fluorinated reagent for the synthesis of gem‐difluorostyrenes and their heterocyclic analogues – 2,2‐difluorovinyl pinacolborane (CF2=CHBPin) was developed. In particular, borylation of 1,1‐difluoroethylene with isopropoxy pinacolborane afforded the title compound on a multigram scale as stable, easy‐to‐handle liquid which can be stored at +4 °C for months. The Pd(dppf)Cl2‐catalyzed cross‐coupling of this reagent with (het)aryl and vinyl bromides works well with broad spectrum of substrates and is characterized by good yields, functional group tolerance, sufficient reproducibility, as well as scalability. [ABSTRACT FROM AUTHOR]

The synthesis of a C1–C14 fragment of the macrolide antibiotic gulmirecin B through formation of the C7–C8 bond by addition of a vinyllithium intermediate to a C1–C7 aldehyde was investigated. This crucial coupling was successful with a vinyllithium reagent corresponding to a C8–C12 fragment. The C8–C12 vinyl bromide was prepared from l -malic acid. The C1–C7 aldehyde building block was synthesized from hex-5-enoic acid by using an Evans alkylation, a cross-metathesis, and an asymmetric dihydroxylation as key steps. [ABSTRACT FROM AUTHOR]

Hexabromocyclododecanes (HBCDs) have been frequently detected in environment. The isomerization between HBCDs and thermodynamic properties of unimolecular and bimolecular decomposition reactions of (−)-α-HBCD and (−)-γ-HBCD have been investigated using the quantum chemical method. The results show that isomerization via 1,2-shift of Br atoms occurs between the (−)-α/(−)-γ, (+)-α/(+)-γ, and (+)-β/(−)-β counterparts of HBCDs. Self-decomposition of HBCDs to pentabromocyclododecenes and HBr progresses slowly at low temperature but becomes competitive with the isomerization reactions at high temperature. The generated products are also toxic pollutants to the aquatic organisms. The reaction of two commonly detected HBCDs, (−)-γ-HBCD and (−)-α-HBCD, with OH radical and H atom have been studied. (−)-γ-HBCD has bigger rate constants in the reaction with OH radical and H atom than (−)-α-HBCD all over studied temperature. After a series of unimolecular or bimolecular reactions, the formed pentabrominated intermediate can decompose into ethane, vinyl bromide, and 1,2-dibromoethylene after sufficient heat adsorption. [ABSTRACT FROM AUTHOR]

Furthermore, the cross-couplings of the cyclic vinyl bromides, such as 3-bromo-1,2-dihydronaphthalene and 3-bromo-3-fluoro-1,2-dihydronaphthalene, with B 1-ZnCl b also proceeded smoothly to yield the corresponding -boryl-substituted allylic boronate esters B 3k b and B 3l b in 90% and 65% yields, respectively. Keywords: Palladium; Negishi coupling; Allylboronate ester; gem-diborylalkane; Cross-coupling EN Palladium Negishi coupling Allylboronate ester gem-diborylalkane Cross-coupling 499 501 3 03/22/21 20210301 NES 210301 We have developed Pd-catalyzed Negishi cross-coupling of diborylmethylzinc chloride with vinyl bromides. GLO:1CJF/01mar21:bkcs12212-fig-0003.jpg PHOTO (COLOR): 3 Further transformations of -boryl-substituted allylic boronate ester 3m. gl In conclusion, we have reported the Pd-catalyzed cross-coupling of vinyl bromides with diborylmethylzinc halides B 1-ZnX b . As depicted in Scheme 2, the coupling reactions of ( I E i )-vinyl bromides bearing various alkyl substituents at the -position proceeded without difficulties, giving -boryl-substituted allylic boronate esters B 3a b - B 3e b in good-to-moderate yields. [Extracted from the article]

The synthesis of di-cationic surfactants were occurred by the reaction of three straight-chain amide derivatives with (2-bromoethyl)trimethylammonium bromide. After characterization of these di-cationic surfactants using FT-IR and NMR, the corrosion inhibition tests were performed at room temperature (25°C) in 1.0, 2.0 and 4.0 M of HCl solutions for different immersion times. Over 92% of corrosion inhibition efficiencies were obtained from the weight loss measurements. As evidence for the preventing of the oxidation on carbon steel, very small amount of corrosion rates were measured from the weight loss values. To establish the inhibition efficiency results in 1.0, 2.0 and 4.0 M of HCl solutions, SEM analysis of the metal coupons used were performed. [ABSTRACT FROM AUTHOR]

A new fluorosulfonylation reagent 1-bromoethene-1-sulfonyl fluoride was developed (1-Br-ESF). This unique reagent possesses three addressable handles (vinyl, bromide, and sulfonyl fluoride) and has great potential to function as a tris-electrophile and as a sulfur(vi) fluoride exchange (SuFEx) clickable material to enrich the SuFEx tool cabinet. The application of this reagent for regioselective synthesis of 5-sulfonylfluoro isoxazoles has been realized through a [3+2] cycloaddition with N-hydroxybenzimidoyl chlorides. This practical protocol provides a general and direct route to functionalized isoxazoles possessing sulfonyl fluoride moieties. [ABSTRACT FROM AUTHOR]

The depletion of ethene, C 2 H 4 , dispersed in solid neon was measured upon irradiation with ultraviolet light from a synchrotron source. The threshold for the dissociation of solid ethene is wavelength 210 ± 5 nm, corresponding to energy 5.90 ± 0.13 eV. We recorded emission spectra for the transition T → N of ethene dispersed in solid neon, dinitrogen and water, excited at 220 nm; the band origins are 286.5, 289.8 and 290.0 nm, respectively. This investigation of the depletion of icy ethene with UV light enhances our understanding of its photochemistry in astronomical environments. This emission feature of solid ethene can provide a new means of identification for its observation in space. [ABSTRACT FROM AUTHOR]

An N-vinylation of imidazole and benzimidazole with a paramagnetic vinyl bromide was investigated. Among the tested procedures, Pd-catalyzed reaction was the most powerful one. The N-vinylation of 2-aminobenzimidazole with a β-bromo-α,β-unsaturated pyrroline nitroxide aldehyde offered 1,1,3,3-tetramethyl-1H-benzimidazo[1,2-a]pyrrolo[3,4-e]pyrimidin-2(3H)-yloxyl radical and the corresponding non-cyclized Schiff base. The reaction of a β-bromo-α,β-unsaturated pyrroline nitroxide aldehyde with imidazole gave β-imidazo-α,β-unsaturated pyrroline nitroxide aldehyde, which was reduced to the alcohol and converted to an unstable allyl chloride. [ABSTRACT FROM AUTHOR]

Abstract: Vinyl‐Bor‐At‐Komplexe, hergestellt aus Enantiomeren‐angereicherten Alkylpinakolboronsäureestern, durchlaufen stereospezifische, radikalisch induzierte 1,2‐Wanderungen in radikalisch/ionischen Kreuzungsreaktionen. In dieser Dreikomponentenreaktion können verschiedene kommerziell erhältliche Alkyliodide als Radikalvorstufen verwendet werden, und Licht fungiert als Ketteninitiator. Eine nachfolgende Oxidation oder Protodeborylierung führt zu wertvollen α‐chiralen Ketonen und chiralen Alkanen mit exzellenten Enantiomerenreinheiten. [ABSTRACT FROM AUTHOR]

The synthesis of highly substituted 1,3-dienes from the coupling of vinyl bromides with vinyl triflates is reported for the first time. The coupling is catalyzed by a combination of (5,5'-bis(trifluoromethyl)-2,2'-bipyridine)NiBr2 and (1,3-bis(diphenylphosphino)-propane)PdCl2 in the presence of a zinc reductant. This method affords tetra- and penta-substituted 1,3-dienes that would otherwise be difficult to access and tolerates electron-rich and -poor substituents, heterocycles, an aryl bromide, and a pinacol boronate ester. Mechanistically, the reaction appears to proceed by an unusual zinc-mediated transfer of a vinyl group between the nickel and palladium centers. [ABSTRACT FROM AUTHOR]

The potential of compound-specific stable isotope analysis (CSIA) to characterize biotransformation of brominated organic compounds (BOCs) was assessed and compared to chlorinated analogues. Sulfurospirillum multivorans and Desulfitobacterium hafniense PCE-S catalyzed the dehalogenation of tribromoethene (TBE) to either vinyl bromide (VB) or ethene, respectively. Significantly lower isotope fractionation was observed for TBE dehalogenation by S. multivorans (ε C = −1.3 ± 0.2‰) compared to D. hafniense (ε C = −7.7 ± 1.5‰). However, higher fractionation was observed for dibromoethene (DBE) dehalogenation by S. multivorans (ε C = −16.8 ± 1.8‰ and −21.2 ± 1.6‰ for trans - and cis -1,2- (DBE) respectively), compared to D. hafniense PCE-S (ε C = −9.5 ± 1.2‰ and −14.5 ± 0.7‰ for trans -1,2-DBE and cis- 1,2-DBE, respectively). Significant, but similar, bromine fractionation was observed for for S. multivorans (ε Br = −0.53 ± 0.15‰, −1.03 ± 0.26‰, and −1.18 ± 0.13‰ for trans -1,2-DBE, cis- 1,2-DBE and TBE, respectively) and D. hafniense PCE-S (ε Br = −0.97 ± 0.28‰, −1.16 ± 0.36‰, and −1.34 ± 0.32‰ for cis -1,2-DBE, TBE and trans- 1,2 - DBE, respectively). Variable C Br dual-element slopes were estimated at Λ (ε C /ε Br ) = 1.03 ± 0.2, 17.9 ± 5.8, and 29.9 ± 11.0 for S. multivorans debrominating TBE, cis- 1,2-DBE and trans- 1,2-DBE, respectively, and at 7.14 ± 1.6, 8.27 ± 3.7, and 8.92 ± 2.4 for D. hafniense PCE-S debrominating trans- 1,2-DBE, TBE and cis- 1,2-DBE, respectively. A high variability in isotope fractionation, which was substrate property related, was observed for S. multivorans but not D. hafniense , similar as observed for chlorinated ethenes, and may be due to rate-limiting steps preceding the bond-cleavage or differences in the reaction mechanism. Overall, significant isotope fractionation was observed and, therefore, CSIA can be applied to monitor the fate of brominated ethenes in the environment. Isotope effects differences, however, are not systematically comparable to chlorinated ethenes. [ABSTRACT FROM AUTHOR]

The electron-induced reaction of physisorbed vinyl bromide (ViBr) and allyl bromide (AllBr) on Cu(110) at 4.6 K was studied experimentally by scanning tunneling microscopy and theoretically by molecular dynamics. ViBr and AllBr were found to react by two pathways: "Direct", in which the molecule reacted under the tip, and "Delayed", in which reaction occurred spontaneously after the molecule had diffused across the surface away from the tip. The novel pathway of Delayed reaction constituted a major route for both vinyl bromide (68%) and allyl bromide (53%). The observed reaction dynamics for ViBr and AllBr gave evidence of a long-lived vibrationally excited intermediate for both Direct and Delayed reactions. Molecular dynamics simulations with reagent excitation by way of selected vibrational normal modes resulted in either Direct or Delayed reaction, depending on the vibrational mode. [ABSTRACT FROM AUTHOR]

Herein, a general procedure to access CF2PO(OEt)2-containing molecules is reported. The reagent CuCF2PO(OEt)2 is accessible by a simple protocol and a broad range of substrates can be functionalised. The procedure allows the conversion of aryl diazonium salts, as well as aryl, heteroaryl, vinyl and alkynyl iodonium salts, into the corresponding fluorinated molecules at room temperature. Mechanistic studies were performed to gain a better understanding of the reaction pathway. Under similar conditions, vinyl and aryl iodides, allyl halides, and benzyl bromides were also functionalised, and the scope and limitations of the reaction were studied. Finally, the procedure was extended to disulfides to offer new access to SCF2PO(OEt)2-containing molecules. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Mizoroki-Heck coupling based new method of polymerization of a-bromostyrene derivatives is developed to synthesize substituted poly(phenylacetylene)s. • Branched poly(phenylacetylene)s are synthesized by using bifunctional vinyl halide monomers. • End-group functionalization of synthetic poly(phenylacetylene)s is achieved via Mizoroki-Heck coupling reaction of terminal vinyl bromide and alkene functionalities. Polyacetylene and its derivatives are a class of traditional conjugated polymers that started the era of conducting plastics. In this paper, we develop a new approach of synthesizing substituted poly(phenylacetylene)s through Mizoroki-Heck coupling of vinyl bromides. A series of α-bromostyrene derivatives are synthesized and used as the monomers for the polycoupling reaction. It is found that K 2 CO 3 is the effective base while Et 3 N shows almost no catalytic reactivity. Gel permeation chromatography (GPC) results indicate that the molecular weight distribution is broad, which is typical for step growth polymerization. A kinetic study shows that electron withdrawing group on the phenyl ring increase the polymerization rate of the corresponding monomer. Furthermore, incorporating both aryl and vinyl halides into a single vinyl monomer allows the synthesis of branched polyacetylene possessing oligo(phenylene vinylene) at the branch points. The current approach may serve as a new tool for the molecular engineering of substituted polyacetylene materials. [ABSTRACT FROM AUTHOR]

Ortho-alkynylated α-bromocinnamates can be converted by a visible-light-mediated photocascade reaction with molecular oxygen into either indenones or dihydroindeno[1,2-c]chromenes. The one-step process features key photochemical steps, that is, the initial activation of vinyl bromides through energy transfer to give α-ketoradicals in a reaction with molecular oxygen, followed by α-oxidation of an arene moiety by 6-π electrocyclization, and subsequent hydroxylation by an electron-transfer process from the same photocatalyst leads to the dihydroindeno[1,2-c]chromenes. [ABSTRACT FROM AUTHOR]

A series of new 3-substituted-4-iodo-(2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-1-yl)oxidanyl compounds is synthesized to achieve NH2- and SH-specific spin labels. The new vinyl iodides are tested in Sonogashira and Buchwald-Hartwig cross-coupling reactions to produce a paramagnetic ß-amino acid ester, pyrroline nitroxidecondensed heterocycles, including a paramagnetic a,a'-dipyridyl ligand and a spin-labeled sulfonamide. [ABSTRACT FROM AUTHOR]

An efficient method for the stereoselective synthesis of vinyl iodides is described. The reactions of vinyl bromides with potassium iodide proceed smoothly in the presence of a copper catalyst under mild reaction conditions to produce the corresponding vinyl iodides stereospecifically and in satisfactory to excellent yields. [ABSTRACT FROM AUTHOR]

The use of pyridine as the sole ligand for the reductive vinylation of unactivated secondary alkyl halides under Ni-catalyzed conditions has been developed. Both alkyl- and aryl-substituted vinyl bromides are suitable, in which alkyl-decorated α-alkenyl bromides resulted in the α-products in good results. [ABSTRACT FROM AUTHOR]

A molecularly imprinted mesoporous silica-based fluorescent sensor was prepared using a tetraphenylethene derivative (TBPE) as a signal transducer. Diethylstilbestrol (DES) was chosen as a target molecule and was connected to two triethoxysilane groups via thermally reversible urethane bonds. DES imprinted cavities with two-point binding sites were formed between the pores of the mesoporous silica by the sol-gel reaction and subsequent removal of DES. TBPE was selectively introduced to the pore surface. TBPE-grafted, DES imprinted mesoporous silica nanoparticle (TBPE-DIMSNP) showed a specific binding ability for the target template. The degree of fluorescence quenching of TBPE-DIMSNP was proportional to the concentration of DES. The sensitivity and selectivity of TBPE-DIMSNP were estimated by the Stern-Volmer equation. TBPE-DIMSNP displayed a much larger Stern-Volmer quenching constant for DES than for DES analogs with a high molecular imprinting factor. TBPE-DIMSNP also exhibited a great recovery of its initial fluorescence intensity even after several extraction and rebinding cycles. [ABSTRACT FROM AUTHOR]

This work presents experimental results on the inhibition performance of kinetic hydrate inhibitors (KHIs) of structure-II hydrates. The studied KHIs, namely derivatives of copolymers of N -vinylcaprolactam (VCap) and alkylimidazolium salts, were synthesized at the Mexican Petroleum Institute with the objective of producing copolymers with higher cloud points than that exhibited by the poly( N -vinylcaprolactam) homopolymer. Three experimental methods were used to evaluate the hydrate inhibition performance of the synthesized copolymers: the capacity to inhibit the formation of tetrahydrofuran (THF) hydrates (under atmospheric pressure and at a temperature of −0.5 °C; i.e., a subcooling for THF hydrates of about 3.4 °C); the capacity to inhibit the formation of natural gas hydrates under high pressure (about 6 MPa) and low temperature conditions (about 1 °C; i.e. a subcooling of 16 °C for the studied natural gas sample); and the determination of the cloud point temperature of the studied copolymers in aqueous systems of varying salinity (under atmospheric pressure and temperatures ranging from 2 to 81 °C). The inhibition performance and the high solubility (in highly saline aqueous systems) of the synthesized copolymers seems to indicate that these compounds can be considered as promising low dosage inhibitors to prevent or delay the formation of hydrates during the production and transport of hydrocarbons. [ABSTRACT FROM AUTHOR]