Ethyl Vinyl Ether Research Articles

Sodium salts of anionic chiral cobalt(III) complexes as catalysts of the enantioselective Povarov reaction.

The sodium salts of anionic chiral cobalt(III) complexes (CCC(-) Na(+) ) have been found to be efficient catalysts of the asymmetric Povarov reaction of easily accessible dienophiles, such as 2,3-dihydrofuran, ethyl vinyl ether, and an N-protected 2,3-dihydropyrrole, with 2-azadienes. Ring-fused tetrahydroquinolines with up to three contiguous stereogenic centers were thus obtained in high yields, excellent diastereoselectivities (endo/exo up to >20:1), and high enantioselectivities (up to 95:5 e.r.).

Effect of α-Heteroatoms on the Formation of Alkene-Derived Monolayers on H-Si(111): A Combined Experimental and Theoretical Study.

We investigate herein whether the reactivity and surface coverage of 1-alkenes toward hydrogen-terminated Si(111) surfaces [H-Si(111)] can be improved by introducing heteroatoms such as oxygen and sulfur at the α-position next to the alkene functional group. To this end, the reactivity of 1-pentene, 1-pentyne, vinyl ethyl ether, and vinyl ethyl sulfide toward H-Si(111) and the surface coverage of the resulting monolayers were studied and compared. All modified surfaces were characterized by static water contact angle measurements, ellipsometry, X-ray photoelectron spectroscopy (XPS), and infrared absorption reflection spectroscopy (IRRAS). Quantum chemical calculations were performed to calculate the activation barriers and driving forces for monolayer formation at the M11-L/6-311G(d,p) level of theory. Both experiments and theory indicate that the presence of α-heteroatoms next to the alkene function improved both the reactivity and surface coverage on H-terminated Si(111) surfaces.

Ethanol purification with ozonation, activated carbon adsorption, and gas stripping

Fermentation of sugar to produce ethanol also produces volatile byproducts. This study was aimed at purifying corn-based ethanol for industrial and pharmaceutical use. The research was on treatment for 10 impurities removal after distillation. The ethanol headspace was sampled with solid-phase microextraction and analyzed with gas chromatography–mass spectrometry. A 40mg/L ozone treatment resulted in >56% and >36% removal of styrene and 2-pentylfuran, respectively, without significant generation of byproducts. A 60g/L activated carbon (AC) treatment with 270min adsorption time resulted in 84%, >72%, and >78% removal of ethyl hexanoate, ethyl octanoate, and ethyl decanoate respectively. CO2-based stripping, at 675LStripping gas/LSample, removed 65%, >82%, and >83% acetaldehyde, ethyl vinyl ether, and 1,1-diethoxyethane respectively. A combination of three approaches effectively removes these 8 impurities.

Asymmetric Total Synthesis of (-)-Englerin A through Catalytic Diastereo- and Enantioselective Carbonyl Ylide Cycloaddition.

An asymmetric total synthesis of the guaiane sesquiterpene (-)-englerin A, a potent and selective inhibitor of the growth of renal cancer cell lines, was accomplished. The basis of the approach is a highly diastereo- and enantioselective carbonyl ylide cycloaddition with an ethyl vinyl ether dipolarophile under catalysis by dirhodium(II) tetrakis[N-tetrachlorophthaloyl-(S)-tert-leucinate], [Rh2 (S-TCPTTL)4 ], to construct the oxabicyclo[3.2.1]octane framework with concomitant introduction of the oxygen substituent at C9 on the exo-face. Another notable feature of the synthesis is ruthenium tetraoxide-catalyzed chemoselective oxidative conversion of C9 ethyl ether to C9 acetate.

Acetoxy-Substituted Cyclopropane Dicarbonyls as Stable Donor-Acceptor-Acceptor Cyclopropanes.

A study of cyclopropanations of oxy-substituted ethenes with ethyl α-diazoaroyl acetates is described. Whereas trimethylsilyl vinyl ether and ethyl vinyl ether gave dihydrofuran products, stable cyclopropanes were isolated when vinyl acetate was used. Yields ranged from 0-87%, depending on the nature and position of the aryl ring substituent.

ChemInform Abstract: A Facile One‐Pot Synthesis of 2‐(2‐Pyridyl)quinolines via Povarov Reaction.

AbstractThe title reaction starts from anilines, hetaryl aldehydes, and ethyl vinyl ether and is incompatible with sterically hindered or halogen‐containing anilines.

Synthesis of 1,2,3-Substituted Pyrroles from Propargylamines via a One-Pot Tandem Enyne Cross Metathesis-Cyclization Reaction.

Enyne cross metathesis of propargylamines with ethyl vinyl ether enables the one-pot synthesis of substituted pyrroles. A series of substituted pyrroles, bearing alkyl, aryl, and heteroaryl substituents, has been synthesized in good yields under microwave irradiation. The reactions are rapid and procedurally simple and also represent a facile entry to the synthetically challenging 1,2,3-substituted pyrroles. The value of the methodology is further corroborated by the conversion of pyrroles into 3-methyl-pyrrolines and the derivatization of the 3-methyl-substituent arising from the metathesis reaction.

Synthesis of poly(vinyl ether)-based, ABA triblock-type thermoplastic elastomers with functionalized soft segments and their gas permeability

The ABA-type triblock copolymers consisting of poly(2-adamantyl vinyl ether) [poly(2-AdVE)] as outer hard segments and poly(6-acetoxyhexyl vinyl ether) [poly(AcHVE)], poly(6-hydroxyhexyl vinyl ether) [poly(HHVE)], or poly(2-(2-methoxyethoxy)ethyl vinyl ether) [poly(MOEOVE)] as inner soft segments were synthesized by sequential living cationic polymerization. Despite the presence of polar functional groups such as ester, hydroxyl, and oxyethylene units in their soft segments, the block copolymers formed elastomeric films. The thermal and mechanical properties and morphology of the block copolymers showed that the two polymer segments of these triblock copolymers were segregated into microphase-separated structure. Effect of the functional groups in the soft segments on gas permeability was investigated as one of the characteristics of the new functional thermoplastic elastomers composed solely of poly(vinyl ether) backbones. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1114–1124

A comprehensive study of the solvent effects on the cycloaddition reaction of diethyl azodicarboxylate and ethyl vinyl ether: Efficient implementation of QM and TD-DFT study

In this work, quantum chemistry calculations performed to study the kinetics and thermodynamic parameters of [2+2] cycloaddition reaction of diethyl azodicarboxylate and ethyl vinyl ether in eighty-three solvents and gas phase. The solvent effect on the reaction path and electron density of the C2N6 critical bond as the reaction coordinate at the TS was investigated. Calculated rate constants in various solvents showed that increase in the activation dipole moment accelerates the reaction. Based on the time-dependent studies, using a conductor like polarizable continuum model solvation model, the solvent effects on the excitation energies of the reactants and transition states (TSs) and the corresponding chemical shifts were analyzed. Finally, some correlations between the rate constant and quantum reactivity indices such as electrophilicity index, chemical hardness, and electronic chemical potential were investigated. © 2014 Wiley Periodicals, Inc.

A facile one-pot synthesis of 2-(2-pyridyl)quinolines via Povarov reaction

An efficient synthesis of 2-(2-pyridyl)quinolines was achieved via a three-component Povarov reaction of aromatic aldehydes, anilines, and ethyl vinyl ether under boron trifluoride methyl etherate (BF3·O(CH3)2) acid catalysis. The developed methodology for the preparation of 2-(2-pyridyl)quinolines offers several advantages over previous methods including mild reaction conditions, easy work-up, a wide range of substrate applicability, and products in good yields.

ChemInform Abstract: Synthetic Utility of Propylphosphonic Anhydride—DMSO Media: An Efficient One‐Pot Three‐Component Synthesis of 2‐Arylquinolines.

Propylphosphonic anhydride (T3P®)–DMSO-mediated one-pot three-component synthesis which provides 2-arylquinolines in a single step from benzyl alcohols, anilines, and ethyl vinyl ether by the modif...

Synthesis of substituted-3-iodo-1H-pyrazole derivatives and their further modification under Sonogashira cross coupling reaction conditions

A convenient synthetic route for preparation of val uable synthetic intermediates - 1-(1- ethoxyethyl)-3-iodo-1H-pyrazole derivatives has been developed. During th is work protection reaction of N-H bond in substituted 3-iodo-1 H-pyrazole derivatives with ethyl vinyl ether and migration of ethoxyethyl protecting group was inves tigated. Synthetic possibilities of Sonogashira cross-coupling reactions of substituted 1-(1-ethoxy ethyl)-3-iodo-1H-pyrazole derivatives with phenylacetylene were studied and evaluated.

Rational Design of Oxirane Monomers for Efficient Crossover Reactions in Concurrent Cationic Vinyl-Addition and Ring-Opening Copolymerization with Vinyl Ethers

Rational structural design of oxirane monomers is demonstrated here to be highly conducive to crossover reactions in the concurrent cationic vinyl-addition and ring-opening copolymerization of alkyl vinyl ethers and oxiranes. The key to the efficient crossover reactions was the smooth transformation of the once-formed oxirane-derived oxonium ion into the ring-opened carbocation, which then reacted with a vinyl monomer. For example, oxiranes that form resonance-stabilized, allyl-type carbocations (i.e., isoprene monoxide and butadiene monoxide) were polymerized through efficient crossover reactions in copolymerization with isopropyl vinyl ether, yielding copolymers composed of relatively short monomer sequences. In particular, the copolymerization of isoprene monoxide and isopropyl vinyl ether generated random or alternating-rich copolymers. The reaction using an oxirane that forms tertiary carbocations (isobutylene oxide) also proceeded via crossover reactions; however, the crossover frequency was lower, which resulted in a multiblock-like copolymer. In contrast to the three oxiranes that yielded copolymers, oxiranes that possibly result in secondary carbocations from their ring-opening (3,3-dimethyl-1,2-butylene oxide and 1,2-butylene oxide) hardly induced crossover reactions. In addition to the ease of carbocation generation via ring-opening, the nucleophilicity of the monomer and the reactivity of the oxirane-derived carbocations were shown to substantially affect the copolymerization behavior. These factors are discussed on the basis of the monomer reactivity ratios that were determined for the copolymerization systems using vinyl ethers with different reactivities, i.e., isopropyl vinyl ether or ethyl vinyl ether, toward oxiranes.

Photo-induced living cationic copolymerization of isobutyl vinyl ether and vinyl ether with carbazolyl groups

In this work, a fluorescent monomer 2-(9-carbazolyl) ethyl vinyl ether (CEVE) was synthesized in our lab, and its photo-induced living cationic copolymerization behavior with isobutyl vinyl ether (IBVE) was investigated in detail using diphenyliodonium chloride (DPICl)/2,2-dimethoxy-2-phenylacetophenone (DMPA) and zinc bromide (ZnBr2) initiating system in dichloromethane solution at 5 °C, −5 °C, and −15 °C, respectively. The living nature of this copolymerization system was confirmed by adding fresh comonomer method after the copolymerization almost finished. In addition, the obtained fluorescent copolymer poly(IBVE-co-CEVE) has a low glass transition temperature (T g), below −10 °C.

Mechanism and selectivity of N-triflylphosphoramide catalyzed (3(+) + 2) cycloaddition between hydrazones and alkenes.

Brønsted acid catalyzed (3(+) + 2) cycloadditions between hydrazones and alkenes provide a general approach to pyrazolidines. The acidity of the Brønsted acid is crucial for the catalytic efficiency: the less acidic phosphoric acids are ineffective, while highly acidic chiral N-triflylphosphoramides are very efficient and can promote highly enantioselective cycloadditions. The mechanism and origins of catalytic efficiencies and selectivities of these reactions have been explored with density functional theory (M06-2X) calculations. Protonation of hydrazones by N-triflylphosphoramide produces hydrazonium-phosphoramide anion complexes. These ion-pair complexes are very reactive in (3(+) + 2) cycloadditions with alkenes, producing pyrazolidine products. Alternative 1,3-dipolar (3 + 2) cycloadditions with the analogous azomethine imines are much less favorable due to the endergonic isomerization of hydrazone to azomethine imine. With N-triflylphosphoramide catalyst, only a small distortion of the ion-pair complex is required to achieve its geometry in the (3(+) + 2) cycloaddition transition state. In contrast, the weak phosphoric acid does not protonate the hydrazone, and only a hydrogen-bonded complex is formed. Larger distortion energy is required for the hydrogen-bonded complex to achieve the "ion-pair" geometry in the cycloaddition transition state, and a significant barrier is found. On the basis of this mechanism, we have explained the origins of enantioselectivities when a chiral N-triflylphosphoramide catalyst is employed. We also report the experimental studies that extend the substrate scope of alkenes to ethyl vinyl ethers and thioethers.

β-Aryl-α-nitro-α,β-enals as heterodienes and dienophiles.

As demonstrated with the β-(2-furyl)-substituted analogue 1b, β-aryl-α-nitro-α,β-enals (1) behave as heterodienes against enamines and enol ethers using their enal unit (e.g., 1b → 12). α-Nitro-α,β-enals can act as well as highly reactive dienophiles to render adducts endowed with nitrogenated quaternary centers (e.g., 1b → 15a). A hetero-Diels-Alder (HDA)/Diels-Alder (DA) sequence from 1b also proved feasible on serial treatment with ethyl vinyl ether and Danishefsky's diene (1b → 14).

Improving Thermal and Optical Properties of Biodegradable Poly(ethyl vinyl ether-co-maleic anhydride) (PEVE/MA) Copolymer by Encapsulation of TiO2 Nanoparticles Via in situ Radical Polymerization

This study deals with the synthesis of alternative nanocomposite of poly (ethyl vinyl ether- maleic anhydride)/ titanium dioxide using maleic anhydride and ethyl vinyl ether as monomers, via a simple and cost-effective method of free-radical polymerization through simultaneous formation of the copolymer matrix and TiO2 nanoparticles networks. Investigations including FT-IR, XRD, SEM, UV-Vis and TGA demonstrated that distribution of TiO2 nanoparticles at polymer matrix was largely homogeneous and compared to the PEVE-MA copolymer, thermal stability of the PEVE-MA/TiO2 was considerably raised, especially in the 10%wt of TiO2 nanoparticles range. Moreover, optical properties of PEVE/MA copolymer were altered and shifted to the visible region.

An experimental and theoretical study of the hetero Diels–Alder reactions between (E)-2-aryl-1-cyano-1-nitroethenes and ethyl vinyl ether: one-step or zwitterionic, two-step mechanism?

The mechanistic aspects of the hetero Diels–Alder reactions between strongly electrophilic (E)-2-aryl-1-cyano-1-nitroethenes and ethyl vinyl ether have been analyzed on the basis of kinetic experimental results as well as quantum chemical simulations of reaction paths. These reactions may theoretically proceed via one step or stepwise, zwitterionic mechanism. It was found that the conversion of addends into adducts carried out via polar, but not zwitterionic mechanism. This is confirmed by kinetic substituent and solvent effects. Subsequently, a detailed analysis of internal reaction coordinate trajectories shows that the title reactions should be considered as examples of “two-stage one-step” cycloadditions according to Domingo terminology.

Convergence of products from Povarov and von Miller reactions: approaches to helquinoline

Yttrium triflate or triflic acid catalysed Povarov reaction of methyl anthranilate with ethyl vinyl ether, both as aldehyde surrogate and as alkene, gave the desired 2-methyl-4-ethoxytetrahydroquinoline diastereoisomers as the major products along with four component coupling von Miller adducts. A proton NMR-study, using yttrium triflate as catalyst, revealed that the cis-diastereoisomers were the initial major products in both the Povarov and von Miller reactions but that these isomerised to the trans-diastereoisomers under the reaction conditions. Two distinct pathways for forming von Miller adducts were uncovered with the initial Povarov products being converted to von Miller adducts under the reaction conditions. Replacement of the 4-ethoxy with a 4-methoxy group under acidic conditions gave predominantly the trans-diastereoisomer, which was subsequently converted to a cis/trans mixture of the tetrahydroquinoline antibiotic helquinoline. It was also possible to convert the von Miller products to Povarov products under acidic conditions.

Diels-Alder reactions of 4-halo masked o-benzoquinones. Experimental and theoretical investigations.

The studies on [4 + 2] cycloaddition of 4-halo derivatives of 6,6-dimethoxycyclohexa-2,4-dienones known as orthoquinone monoketals/masked o-benzoquinones are described. The 4-fluoro, 4-chloro- and 4-iodo-masked o-benzoquinones were stable enough for their isolation and characterization. These conjugated dienones cycloadded with several electron-deficient and electron-rich dienophiles in a highly regio- and stereo-selective manner to afford the corresponding halo bicyclo[2.2.2]octenone derivatives in high to excellent chemical yields. The halo masked o-benzoquinones did not undergo dimerization under the reaction conditions. To evaluate the observed selectivities of these Diels-Alder reactions, we have performed quantum mechanical calculations for the reactions between halo masked o-benzoquinones and methyl vinyl ketone and ethyl vinyl ether at the B3LYP/6-31G** theory level. The differences in HOMO and LUMO energy gaps suggest that these reactions can be classified as inverse electron-demand Diels-Alder reactions. The calculated transition state energies and global electronic indexes supported the experimentally observed selectivities of the reaction in many cases.