Diene Structure Research Articles

Macrolide Synthesis through Intramolecular Oxidative Cross‐Coupling of Alkenes

AbstractA RhIII‐catalyzed intramolecular oxidative cross‐coupling between double bonds for the synthesis of macrolides is described. Under the optimized reaction conditions, macrocycles containing a diene moiety can be formed in reasonable yields and with excellent chemo‐ and stereoselectivity. This method provides an efficient approach to synthesize macrocyclic compounds containing a 1,3‐conjugated diene structure.

Development of Novel Chemical Probes for Examining Triplet Natural Organic Matter under Solar Illumination.

Excited triplet states of chromophoric dissolved organic matter (3CDOM*) are critical transient species in environmental photochemistry. In the present study, sorbic amine (2,4-hexadien-1-amine) and sorbic alcohol were employed as new probe molecules for triplet measurements and compared to the results measured from sorbic acid under identical conditions. Unlike sorbic acid, sorbic amine and sorbic alcohol were not directly photolyzed under solar irradiation. Photosensitized isomerization of the probes with the conjugated diene structure could yield four geometrical isomers. The separation and quantitative determination of the geometrical isomers were accomplished using HPLC and high-resolution NMR analyses. When photoirradiated Suwannee River natural organic matter (SRNOM) was employed as a source of 3CDOM*, significantly different photosensitized isomerization rates were observed for the diverse charged probes. The bimolecular reaction rate constants between 3SRNOM* and the probes were calculated as (0.42 ± 0.1) × 109 M-1 s-1 for sorbic acid, (1.1 ± 0.1) × 109 M-1 s-1 for sorbic alcohol, and (5.2 ± 0.4) × 109 M-1 s-1 for sorbic amine, respectively. The average apparent Φtriplet was (0.96 ± 0.03)% based on an irradiation range of 290 to 400 nm. We developed highly selective and efficient probes for triplet determination and elucidated the different reaction behaviors of these conjugated dienes containing different charged substituents within the photochemical energy transfer process.

Synthesis, structure, and photoreactions of fluorinated 2,11‐diaza[32]paracyclophane: Photochemical formation of cage‐diene type benzene dimer

AbstractAn octafluorinated 2,11‐diaza[32]paracyclophane derivative 12 was prepared, and its photochemical reaction was investigated. Upon irradiation at 300 nm, the fluorinated azacyclophane 12 underwent efficient photodimerization of the benzene cores to afford the corresponding photoisomer 13, which possessed cage diene benzene dimer structure (pentacyclo[6.4.0.0.2,70.3,1206,9]dodeca‐4,10‐diene skeleton). The cage diene structure was established by single‐crystal X‐ray diffraction analysis. The cage diene 13 thermally isomerized to a syn‐o,o′‐dibenzene isomer 22. The activation parameters for the thermal isomerization were determined to be Ea = 121 kJ mol−1, ΔH≠ = 118 kJ mol−1, ΔS≠(293 K) = 22 J mol−1 K−1, and ΔG≠(293 K) = 111 kJ mol−1. It was revealed that, by photoirradiation at 300 nm, the syn‐o,o′‐dibenzene isomer 22 underwent facile intramolecular [π4s + π4s] cycloaddition to reproduce the cage diene isomer 13.

1,1-Difluoronaphthalene-2(1H)-ones in Diels-Alder reaction

1,1-Difluoronaphthalene-2(1H)-ones were proposed as novel fluorinated dienophiles for the Diels-Alder reaction. The influence of the diene structure, reaction conditions on the rate and diastereoselectivity of the Diels-Alder cycloaddition was studied. For the reaction of 1,1-difluoronaphthalene-2(1H)-one with cyclopentadiene a good correlation of the logarithm of endo/exo ratio vs solvent polarity parameters were obtained. The role of diene structure and solvent effects were rationalized on the basis of DFT calculations. The factors influencing the reaction energetics were elucidated by distortion-interaction model approach. Cycloaddition-aromatization sequence was developed for the synthesis of annulated naphthalene derivatives.

An unexplored pathway for degradation of cholate requires a 7α-hydroxysteroid dehydratase and contributes to a broad metabolic repertoire for the utilization of bile salts in Novosphingobium sp. strain Chol11.

Bile salts such as cholate are surface-active steroid compounds with functions for digestion and signaling in vertebrates. Upon excretion into soil and water bile salts are an electron- and carbon-rich growth substrate for environmental bacteria. Degradation of bile salts proceeds via intermediates with a 3-keto-Δ1,4 -diene structure of the steroid skeleton as shown for e.g. Pseudomonas spp. Recently, we isolated bacteria degrading cholate via intermediates with a 3-keto-7-deoxy-Δ4,6 -structure of the steroid skeleton suggesting the existence of a second pathway for cholate degradation. This potential new pathway was investigated with Novosphingobium sp. strain Chol11. A 7α-hydroxysteroid dehydratase encoded by hsh2 was identified, which was required for the formation of 3-keto-7-deoxy-Δ4,6 -metabolites. A hsh2 deletion mutant could still grow with cholate but showed impaired growth. Cholate degradation of this mutant proceeded via 3-keto-Δ1,4 -diene metabolites. Heterologous expression of Hsh2 in the bile salt-degrading Pseudomonas sp. strain Chol1 led to the formation of a dead-end steroid with a 3-keto-7-deoxy-Δ4,6 -diene structure. Hsh2 is the first steroid dehydratase with an important function in a metabolic pathway of bacteria that use bile salts as growth substrates. This pathway contributes to a broad metabolic repertoire of Novosphingobium strain Chol11 that may be advantageous in competition with other bile salt-degrading bacteria.

Continuous Gradient Temperature Raman Spectroscopy of Oleic and Linoleic Acids from -100 to 50°C.

We analyzed the unsaturated fatty acids oleic (OA, 18:1n-9) and linoleic (LA, 18:2n-3), and a 3:1 LA:OA mixture from -100 to 50°C with continuous gradient temperature Raman spectroscopy (GTRS). The 20Mb three-dimensional data arrays with 0.2°C increments and first/second derivatives allowed rapid, complete assignment of solid, liquid, and transition state vibrational modes. For OA, large spectral and line width changes occurred in the solid state γ to α transition near -4°C, and the melt (13°C) over a range of only 1°C. For LA, major intensity reductions from 200 to 1750cm-1 and some peak shifts marked one solid state phase transition at -50°C. A second solid state transition (-33°C) had minor spectral changes. Large spectral and line width changes occurred at the melt transition (-7°C) over a narrow temperature range. For both molecules, melting initiates at the diene structure, then progresses towards the ends. In the 3:1 LA:OA mixture, some less intense and lower frequencies present in the individual lipids are weaker or absent. For example, modes assignable to C8 rocking, C9H-C10H wagging, C10H-C11H wagging, and CH3 rocking are present in OA but absent in LA:OA. Our data quantify the concept of lipid premelting and identify the flexible structures within OA and LA, which have characteristic vibrational modes beginning at cryogenic temperatures.

ChemInform Abstract: Synthesis of Oxazoles by Tandem Cycloisomerization/Allylic Alkylation of Propargyl Amides with Allylic Alcohols: Zn(OTf)2 as π Acid and σ Acid Catalyst.

A Zn(OTf)2-catalyzed tandem cycloisomerization/allylic alkylation of N-(propargyl)arylamides and allylic alcohols to produce oxazole derivatives has been successfully developed. The zinc catalyst served as π acid and also σ acid in this reaction. The target allylic oxazoles have been transformed into multisubstituted diene structures, which are potential aggregation-induced emission active optical materials.

Kinetic Analysis of the Concentration of Conjugated Diene Structures in Glyceryl Trilinoleate During Oxidation

Kinetic Analysis of the Concentration of Conjugated Diene Structures in Glyceryl Trilinoleate During Oxidation

Synthesis of Oxazoles by Tandem Cycloisomerization/Allylic Alkylation of Propargyl Amides with Allylic Alcohols: Zn(OTf)2 as π Acid and σ Acid Catalyst.

A Zn(OTf)2-catalyzed tandem cycloisomerization/allylic alkylation of N-(propargyl)arylamides and allylic alcohols to produce oxazole derivatives has been successfully developed. The zinc catalyst served as π acid and also σ acid in this reaction. The target allylic oxazoles have been transformed into multisubstituted diene structures, which are potential aggregation-induced emission active optical materials.

Role of Acrylic Copolymers in Designing Environmentally Friendly Technologies for Finishing Textile Materials

We present the results of studies aimed at designing environmentally friendly technologies for printing and final finishing of textile materials. The technologies are based on the specific properties of carboxylated acrylic copolymers that can increase the viscosity in an alkaline medium. The obvious connection between negative changes in nature and the anthropogenic impact of industrial plants on the environment has raised general concerns, and requires solving a number of problems involved in the indicated issue. The negative impact of industrial activity on natural processes and living organisms is due not only to its wasteful management but also to shortcomings in the production processes employed [1]. Within the broad range of sectors in the national economy, the textile industry makes an appreciable contribution to environmental pollution and pollution of water and air basins. Considering this fact, improving processes in dyeing-and-finishing departments and designing environmentally friendly technologies for finishing textile materials is a timely and important direction in solving the important problem of reducing the level of toxicological and ecological stress on the environment and designing environmentally friendly textiles meeting international safety and quality standards. In this paper, we present the results of studies to develop environmentally friendly printing and final finishing using acrylic latexes and water-soluble copolymers of domestic manufacture (Nord Sintez LLC). In this case, improvement of the environmental situation is achieved as a result of the following: – using few-component pigment compositions, not containing toxic crosslinking agents; – improving the degree of utilization of reactive dyes and reducing their desorption during washing of printed material, with a corresponding decrease in their input into wastewaters from the dye-and-finishing plant; – designing low-formaldehyde and formaldehyde-free coupling agents, ensuring permanence and high resistance of the effects of final finishing to organic solvents. In the first step, we evaluated the properties of aqueous dispersions of acrylic and styrene-acrylic latexes of domestic manufacture, with the objective of using them as binders in the composition of pigment printing inks. The acrylic latex recommended for use is a copolymer of butyl acrylate, methyl methacrylate, acrylonitrile, and acrylic acids with the optimal ratio of “hard” and “soft” monomer units in the macromolecular chain, which ensures the needed combination of strength and elasticity of the polymer film. Such films are distinguished by high weathering resistance and form coatings that do not yellow over time, in contrast to films based on diene structures which tend to oxidize [2]. We established that an aqueous dispersion of acrylic carboxyl-containing latex MN-10 has low surface tension (36.7 mN/m), comparable with its value for divinyl nitrile latexes BNK 40/4 and BNK 20/35 (respectively 38.4 and 33.1 mN/m). The effective wettability and penetration of cellulose-containing fabrics by printing compositions based on this latex promotes stronger fixation of the pigment particles to the fiber substrate. The light scattering method has shown (Fig. 1) that the average size of MN-10 latex globules is not more than 100 nm, which is responsible for the high degree of homogeneity of the films and their stronger fixation to the polymer substrate [3].

Facile Preparation of α-Cyano-α,ω-Diaryloligovinylenes: A New Class of Color-Tunable Solid Emitters.

An efficient Knoevenagel condensation reaction was used to construct a series of α-cyano-α,ω-diaryloligovinylenes, which show prominent fluorescence emission in the solid state. On investigating the effect of conjugation length on fluorescent properties, we found that the diene structure showed superior solid-state luminescence. Furthermore, the emission color could be adjusted by introducing donor or acceptor functional groups at the terminal aryl groups. Full-color emission in the visible region can be achieved by adding different functional groups to the α-cyano-α,ω-diaryldivinylene moiety. The structure-property relationships were elucidated and some observations such as the substitution position effects were discussed. These compounds have potential applications as full-color solid emissive candidates in material science and their simple structures allow them to be easily modified resulting in further interesting properties.

Molecular design of diene monomers containing an ester functional group for the synthesis of poly(diene sulfone)s by radical alternating copolymerization with sulfur dioxide

ABSTRACTFunctional poly(diene sulfone)s are prepared by the radical alternating copolymerization of 1,3‐diene monomers containing an ester substituent with sulfur dioxide. Methyl 3,5‐hexadienoate (MH) and methyl 5,7‐octadienoate (MO) with both an alkylene spacer and a terminal diene structure are suitable to produce a high‐molecular‐weight copolymer in a high yield, while the copolymerization of 5,7‐nonadienoic acid, ethyl 2,4‐pentadienoate, and ethyl 4‐methyl‐2,4‐pentadienoate including either an alkylene spacer or a terminal diene structure lead to unsuccessful results. The 13C NMR chemical shift values of MH and MO suggest a high electron density at their reacting α‐carbon for exhibiting a high copolymerization reactivity. Fluorene‐containing diene monomers, 9‐fluorenyl 3,5‐hexadienoate (FH) and 9‐fluorenyl 5,7‐octadienoate (FO), are also prepared and copolymerized with sulfur dioxide. The thermal and optical properties of the poly(diene sulfone)s containing the methyl and fluorenyl ester substituents in the side chain are investigated. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1000–1009

Radical Alternating Copolymerization of Twisted 1,3-Butadienes with Maleic Anhydride as a New Approach for Degradable Thermosetting Resin

We report a novel approach for the synthesis of a readily curable and degradable resin by the radical alternating copolymerization of 1,3-diene monomers with maleic anhydride. 2,4-Dimethyl-1,3-pentadiene predominantly produced an alternating copolymer rather than a Diels–Alder adduct during the reaction with maleic anhydride. We revealed the most stable conformation as a twisted diene structure of 2,4-dimethyl-1,3-pentadiene and the other methyl-substituted dienes by DFT calculations, while a completely planar structure was preferred for the s-cis and s-trans conformers of the nonsubstituted butadiene. The highly alternating repeating structure of the produced copolymers was revealed based on the NMR analysis and copolymerization reactivity ratios. The alternating copolymers including an anhydride moiety and a carbon-to-carbon double bond in each repeating unit was conveniently used for the thermosetting, subsequent degradation, and polymer–surface modification by postpolymerization reactions such as epox...

Metabolic Interactions between Vitamin A and Conjugated Linoleic Acid

Lipid-soluble molecules share several aspects of their physiology due to their common adaptations to a hydrophilic environment, and may interact to regulate their action in a tissue-specific manner. Dietary conjugated linoleic acid (CLA) is a fatty acid with a conjugated diene structure that is found in low concentrations in ruminant products and available as a nutritional supplement. CLA has been shown to increase tissue levels of retinol (vitamin A alcohol) and its sole specific circulating carrier protein retinol-binding protein (RBP or RBP4). However, the precise mechanism of this action has not been elucidated yet. Here, we provide a summary of the current knowledge in this specific area of research and speculate that retinol and CLA may compete for catabolic pathways modulated by the activity of PPAR-α and RXR heterodimer. We also present preliminary data that may position PPAR-α at the crossroads between the metabolism of lipids and vitamin A.

Evidence of distinct pathways for bacterial degradation of the steroid compound cholate suggests the potential for metabolic interactions by interspecies cross‐feeding

The distribution and the metabolic pathways of bacteria degrading steroid compounds released by eukaryotic organisms were investigated using the bile salt cholate as model substrate. Cholate-degrading bacteria could be readily isolated from freshwater environments. All isolated strains transiently released steroid degradation intermediates into culture supernatants before their further degradation. Cholate degradation could be initiated via two different reaction sequences. Most strains degraded cholate via a reaction sequence known from the model organism Pseudomonas sp. strain Chol1 releasing intermediates with a 3-keto-Δ(1,4) -diene structure of the steroid skeleton. The actinobacterium Dietzia sp. strain Chol2 degraded cholate via a different and yet unexplored reaction sequence releasing intermediates with a 3-keto-Δ(4,6) -diene-7-deoxy structure of the steroid skeleton such as 3,12-dioxo-4,6-choldienoic acid (DOCDA). Using DOCDA as substrate, two Alphaproteobacteria, strains Chol10-11, were isolated that produced the same cholate degradation intermediates as strain Chol2. With DOCDA as substrate for Pseudomonas sp. strain Chol1 only the side chain was degraded while the ring system was transformed into novel steroid compounds accumulating as dead-end metabolites. These metabolites could be degraded by the DOCDA-producing strains Chol10-11. These results indicate that bacteria with potentially different pathways for cholate degradation coexist in natural habitats and may interact via interspecies cross-feeding.

Anionic Polymerization of 2-Phenyl[3]dendralene and 2-(4-Methoxyphenyl)[3]dendralene

Anionic polymerization of two phenyl-substituted trienes containing cross-conjugated carbon–carbon double bonds, 2-phenyl[3]dendralene (P3D) and 2-(4-methoxyphenyl)[3]dendralene (MP3D), was carried out in THF under a variety of different conditions. Poly(P3D) of controlled molecular weight with a narrow molecular weight distribution was obtained when the polymerization reaction was carried out at −78 °C for 30 min. Broadening of the molecular weight distribution to the higher-molecular-weight side was observed if the polymerization mixture was left to stand for 20 h at −78 °C, presumably because of the attack of the propagating chain-end carbanion at the conjugated diene structure in the polymer chain. Similar broadening occurred if the polymerization was performed at a higher temperature. However, under identical conditions, no such a broadening was observed in the polymerization of MP3D. Block copolymers of predictable molecular weights and compositions containing a poly(2-vinylpyridine) segment were obtained by the sequential addition of P3D and/or MP3D to potassium naphthalenide and then 2-vinylpyridine. Only the conjugate addition structure was found in the resulting polymers.

Morphological structure and surface properties of maleated ethylene propylene diene monomer/organoclay nanocomposites

AbstractThe phase morphology and surface properties of some maleated ethylene propylene‐diene/organoclay nanocomposites (EPDM‐g‐MA/OC) were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle measurements. The effect of organoclay and/or compatibilizing agent [maleic anhydride‐grafted polypropylene (PP‐g‐MA)] on the properties of the EPDM‐g‐MA nanocomposites was investigated. The quality and uniformity of nanoclay dispersion were analyzed by SEM and AFM images. The experimental results showed an intercalate structure and biphasic morphology for the binary blends based on EPDM and clay. The surface properties of the studied composites are significantly influenced by the presence of a compatibilizing agent—PP‐g‐MA. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

ChemInform Abstract: Regioselective Radical Bromoallylation of Allenes Leading to 2‐Bromo‐Substituted 1,5‐Dienes.

AbstractThe process is applied to various substrates to produce highly functionalized diene structures of synthetic importance.

Acid‐Catalyzed Furfuryl Alcohol Polymerization: Characterizations of Molecular Structure and Thermodynamic Properties

AbstractThe liquid‐phase polymerization of furfuryl alcohol catalyzed by sulfuric acid catalysts and the identities of molecular intermediates were investigated by using Raman spectroscopy and density functional theory calculation. At room temperature, with an acid catalyst, a vigorous furfuryl alcohol polymerization reaction was observed, whereas even at a high water concentration, furfuryl alcohol was very stable in the absence of an acid catalyst. Theoretical studies were carried out to investigate the thermodynamics of protonation of furfuryl alcohol, initiation of polymerization, and formation of conjugated dienes and diketonic species by using the B3LYP level of theory. A strong aliphatic CC band observed in the calculated and measured Raman spectra provided crucial evidence to understand the polymerization reaction mechanism. It is confirmed that the formation of a conjugated diene structure rather than a diketone structure is involved in the furfuryl alcohol polymerization reaction.

ChemInform Abstract: Synthesis of Highly Functionalized Biaryls by Condensation of 2‐Fluoro‐1,3‐bis(silyloxy) 1,3‐Dienes with 3‐Cyanochromones and Subsequent Domino “Retro‐Michael/Aldol/Fragmentation”.

AbstractTmsOTf‐mediated coupling is followed by treatment with NEt3 to provide azaxanthones and/or highly functionalized biaryls depending on the diene structure.