Diene Component Research Articles

ChemInform Abstract: Synthesis of Novel and Complex Tetrahydroquinazolinedione and Dihydropyrido[2,3‐d]pyrimidine Derivatives via a One‐Pot [4 + 2]‐Cycloaddition Strategy.

AbstractUracil derivatives (I) and (IV) are employed as diene components for the reaction with aromatic nitroalkenes.

Regiospecific Normal Diels-Alder Reaction of trans-1,2-Biscoumarinylethenes

The reaction of different 7,8-substituted coumarin 4-acetic acids with 7-diethylaminocoumarin-3-carbaldehyde in the presence of piperidine in methanol gives 1,2-biscoumarinylethenes. These compounds undergo regiospecific Diels–Alder reactions at their electron-rich diene components C₃–C₄–C₁₀–C₉, with electron-deficient dienophiles. The feasibility of normal electron-demand Diels–Alder reactions could be explained on the basis of the HOMO–LUMO gap. All the compounds are new and are intensely colored.

Effect of Epoxidation of Diene Component of SBS Block Copolymer on Morphology and Mechanical Properties

AbstractIn this work, the polybutadiene (PB) block of an asymmetric lamellae forming polystyrene/polybutadiene based triblock copolymer was epoxidized to different extent in order to study its effect on morphology and mechanical behaviour of the copolymer. The products were analyzed by means of different microscopic techniques, Fourier transform infrared (FTIR) spectroscopy and microhardness measurements. It was found that the microphase separation behavior and hence the mechanical properties of the materials were drastically altered through epoxidation of the diene block of the styrene/diene triblock copolymer. With the increase in the extent of epoxidation the lamellar structure changed to distorted lamellae and then to disordered domains. Consequently, inhomogeneous mechanical performance of the samples was observed at higher degree of chemical modification.

Photo Retro-Diels–Alder Reactions

Photo-retro-Diels-Alder (PrDA) reactions of a variety of Diels-Alder (DA) adducts were studied. Experimental results showed that the photoreactivity (quantum yield) depends on the electron-donating ability of the diene component and the electron-withdrawing ability of the dienophile component. The mechanism was studied by trapping the reaction intermediate, O(2) quenching, time-resolved absorption, and fluorescence spectroscopy. All the results support a mechanism that involves a charge-separated intermediate generated from a singlet excited state. The PrDA reaction may find applications in photoresponsive materials, photolithography, drug delivery, and mechanistic research.

A Metathesis Approach to Volatile Olefins: Synthesis of 18O‐Allyl Alcohol

A neat reaction: A ring-closing metathesis (RCM) strategy is presented in which the two termini of a light, and thus volatile, isotopically labelled olefin are held separate by way of a higher molecular weight diene component, allowing synthetic manipulations to be conducted without difficulty. Using simple laboratory apparatus, a solvent-free catalytic RCM process can be achieved that avoids side reactions and allows isolation of the alkene in high purity.

Intramolecular Diels–Alder chemistry of 4-vinylimidazoles

An investigation of 4-vinylimidazoles as diene components in the intramolecular Diels-Alder reaction is described. In the course of these studies several parameters affecting the cycloaddition were evaluated including the nature of the imidazole protecting group, the type of dienophile and the linking group. These investigations established that amino linkers were generally more effective than either ethers or esters. In most cases, the cycloadditions were highly stereoselective, resulting in the formation of products derived from an anti transition state. The polysubstituted tetrahydrobenzimidazole core of the pyrrole-imidazole alkaloid ageliferin can be constructed through the use of pseudo dimeric 4-vinylimidazoles.

A density functional theory study on the Diels-Alder reactions with vinylallenes as dienes

The Diels-Alder (DA) reactions of vinylallenes (VA) with ethylenes were investigated using the global electrophilicity and nucleophilicity of the corresponding reactants as global reactivity indexes defined within the conceptual density functional theory. The reactivity and regioselectivity of these reactions were predicted by analysis of the energies, geometries, and electronic nature of the transition-state structures. In general, substitution by the electron-accepting acetyl group favors the reaction, whereas substitution by the electron-releasing methoxy group provides the opposite effect, regardless of being on VA or ethylene. However, the substitution effect in ethylene is apparently greater than that in VA. It has also been disclosed that substitution by electron-accepting group on both reactants accelerates the reaction, and the reaction may give different regioselectivity from that between VA and acetyl-substituted ethylene. This has also been verified by our experiments. It seems that the DA reactions with VAs as the diene components can generally be classified as nonpolar asynchronous with the endo product formation (wherever possible) being more pronounced. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011

Catalytic Asymmetric Formation of δ‐Lactones from Unsaturated Acyl Halides

Previously unexplored enantiopure zwitterionic ammonium dienolates have been utilized in this work as reactive intermediates that act as diene components in hetero-Diels-Alder reactions (HDAs) with aldehydes to produce optically active delta-lactones, subunits of numerous bioactive products. The dienolates were generated in situ from E/Z mixtures of alpha,beta-unsaturated acid chlorides by use of a nucleophilic quinidine derivative and Sn(OTf)(2) as co-catalyst. The latter component was not directly involved in the cycloaddition step with aldehydes and simply facilitated the formation of the reactive dienolate species. The scope of the cycloaddition was considerably improved by use of a complex formed from Er(OTf)(3) and a simple commercially available norephedrine-derived ligand that tolerated a broad range of aromatic and heteroaromatic aldehydes for a cooperative bifunctional Lewis-acid-/Lewis-base-catalyzed reaction, providing alpha,beta-unsaturated delta-lactones with excellent enantioselectivities. Mechanistic studies confirmed the formation of the dienolate intermediates for both catalytic systems. The active Er(III) complex is most likely a monomeric species. Interestingly, all lanthanides can catalyze the title reaction, but the efficiency in terms of yield and enantioselectivity depends directly on the radius of the Ln(III) ion. Similarly, use of the pseudolanthanides Sc(III) and Y(III) also resulted in product formation, whereas the larger La(III) and other transition metal salts, as well as main group metal salts, proved to be inefficient. In addition, various synthetic transformations of 6-CCl(3)- or 4-silyl-substituted alpha,beta-unsaturated delta-lactones, giving access to a number of valuable delta-lactone building blocks, were investigated.

First example of Diels–Alder reaction in the 2,3,4,4a-tetrahydroquinoline series. Synthesis of hydrogenated 5,8-ethanoquinolines

Diels–Alder reactions in the 2,3,4,4a-tetrahydroquinolines series were studied for the first time. It was shown that these dienes demonstrate only moderate reactivity. [4+2] Cycloaddition occurs stereo- and regioselectively only for alkenes bearing an electron-withdrawing group (acrylonitrile, maleic anhydride, dimethyl acetylene dicarboxylate, methyl propiolate). In this case, endo-Diels–Alder adducts, spiroannelated 5,8-ethanoquinolines, are formed in a high yield. Cyclopentadiene, being a highly reactive diene component, reacts with 2,3,4,4a-tetrahydroquinolines as the dienophile. Electron-rich unsaturated compounds ( N-vinylpyrrolidone, vinylethyl ether, phenylacetylene) are inert to this cycloaddition reaction.

Thermal and mechanical properties of in situ polymerized PS/EPDM blends

In situ polymerized PS/EPDM blends were prepared by dissolving poly(ethylene-co-propylene-co-2-ethylidene-5-norbornene) (EPDM) in styrene monomer, followed by bulk polymerization at 60 °C and 80 °C . EPDM has excellent resistance to such factors as weather, ozone and oxidation, attributed to its non-conjugated diene component, and it could be a good alternative for substituting polybutadiene-based rubbers in PS toughening. The in situ polymerized blends were characterized by dynamic mechanical analysis, thermogravimetric analysis, gel permeation chromatography, and tensile and Izod impact resistance tests. The PS/EPDM blends are immiscible and present two phases, a dispersed elastomeric phase (EPDM) in a rigid PS matrix whose phase behavior is strongly affected by the polymerization temperature. Mechanical properties of the blends are influenced by the increase in the average size of EPDM domains with the increase in the polymerization temperature and EPDM content. The blends polymerized at 60 °C containing 5 wt% of EPDM presents an increase in the impact resistance of 80% and containing 17 wt% of EPDM presents an increase in the strain at break of 170% in comparison with the value of PS. The blend polymerized at 80 °C containing 17 wt% of EPDM presents an increase in the strain at break of 480% and in impact resistance of 140% in comparison with the value of PS.

Total Synthesis of Epoxyquinols A (I), B (II), and C (III) and Epoxytwinol A (IV) and the Reactivity of a 2H‐Pyran Derivative as the Diene Component in the Diels—Alder Reaction.

ChemInformVolume 36, Issue 23 Natural Products Total Synthesis of Epoxyquinols A (I), B (II), and C (III) and Epoxytwinol A (IV) and the Reactivity of a 2H-Pyran Derivative as the Diene Component in the Diels—Alder Reaction. Mitsuru Shoji, Mitsuru Shoji Dep. Ind. Chem., Fac. Eng., Sci. Univ. Tokyo, Shinjuku, Tokyo 162, JapanSearch for more papers by this authorHiroki Imai, Hiroki Imai Dep. Ind. Chem., Fac. Eng., Sci. Univ. Tokyo, Shinjuku, Tokyo 162, JapanSearch for more papers by this authorMakoto Mukaida, Makoto Mukaida Dep. Ind. Chem., Fac. Eng., Sci. Univ. Tokyo, Shinjuku, Tokyo 162, JapanSearch for more papers by this authorKen Sakai, Ken Sakai Dep. Ind. Chem., Fac. Eng., Sci. Univ. Tokyo, Shinjuku, Tokyo 162, JapanSearch for more papers by this authorHideaki Kakeya, Hideaki Kakeya Dep. Ind. Chem., Fac. Eng., Sci. Univ. Tokyo, Shinjuku, Tokyo 162, JapanSearch for more papers by this authorHiroyuki Osada, Hiroyuki Osada Dep. Ind. Chem., Fac. Eng., Sci. Univ. Tokyo, Shinjuku, Tokyo 162, JapanSearch for more papers by this authorYujiro Hayashi, Yujiro Hayashi Dep. Ind. Chem., Fac. Eng., Sci. Univ. Tokyo, Shinjuku, Tokyo 162, JapanSearch for more papers by this author Mitsuru Shoji, Mitsuru Shoji Dep. Ind. Chem., Fac. Eng., Sci. Univ. Tokyo, Shinjuku, Tokyo 162, JapanSearch for more papers by this authorHiroki Imai, Hiroki Imai Dep. Ind. Chem., Fac. Eng., Sci. Univ. Tokyo, Shinjuku, Tokyo 162, JapanSearch for more papers by this authorMakoto Mukaida, Makoto Mukaida Dep. Ind. Chem., Fac. Eng., Sci. Univ. Tokyo, Shinjuku, Tokyo 162, JapanSearch for more papers by this authorKen Sakai, Ken Sakai Dep. Ind. Chem., Fac. Eng., Sci. Univ. Tokyo, Shinjuku, Tokyo 162, JapanSearch for more papers by this authorHideaki Kakeya, Hideaki Kakeya Dep. Ind. Chem., Fac. Eng., Sci. Univ. Tokyo, Shinjuku, Tokyo 162, JapanSearch for more papers by this authorHiroyuki Osada, Hiroyuki Osada Dep. Ind. Chem., Fac. Eng., Sci. Univ. Tokyo, Shinjuku, Tokyo 162, JapanSearch for more papers by this authorYujiro Hayashi, Yujiro Hayashi Dep. Ind. Chem., Fac. Eng., Sci. Univ. Tokyo, Shinjuku, Tokyo 162, JapanSearch for more papers by this author First published: 11 May 2005 https://doi.org/10.1002/chin.200523228Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume36, Issue23June 7, 2005 RelatedInformation

Total Synthesis of Epoxyquinols A, B, and C and Epoxytwinol A and the Reactivity of a 2H-Pyran Derivative as the Diene Component in the Diels−Alder Reaction

Full details of two versions of the total synthesis of epoxyquinols A, B, and C and epoxytwinol A (RKB-3564D) are described. In the first-generation synthesis, the HfCl(4)-mediated diastereoselective Diels-Alder reaction of furan with Corey's chiral auxiliary has been developed. In the second-generation synthesis, a chromatography-free preparation of an iodolactone, by using acryloyl chloride as the dienophile in the Diels-Alder reaction of furan, and the lipase-mediated kinetic resolution of a cyclohexenol derivative have been developed. This second-generation synthesis is suitable for large-scale preparation. A biomimetic cascade reaction involving oxidation, 6pi-electrocyclization, and then Diels-Alder dimerization is the key reaction in the formation of the complex heptacyclic structure of epoxyquinols A, B, and C. Epoxytwinol A is synthesized by the cascade reaction composed of oxidation, 6pi-electrocyclization, and formal [4 + 4] cycloaddition reactions. A 2H-pyran, generated by oxidation/6pi-electrocyclization, acts as a good diene, reacting with several dienophiles to afford polycyclic compounds in one step. An azapentacyclic compound is synthesized by a similar cascade reaction composed of the four successive steps: oxidation, imine formation, 6pi-azaelectrocyclization, and Diels-Alder dimerization.

Efficient method to locate double bond positions in conjugated trienes

The double bond positions of 11 conjugated trienes were unambiguously located through a simple derivatization method amenable to nanogram-scale analyses. The trienes were reacted with the powerful dienophile 4-methyl-1,2,4-triazoline-3,5-dione (MTAD), and the mass spectra of the resulting cycloadducts exhibited large diagnostic fragments which allowed the unequivocal location of the double bonds in the parent triene in most cases. Catalytic hydrogenation of the cycloadducts produced saturated compounds with characteristic mass spectral fragments from which the positions of the trienes in the parent compounds could be readily confirmed. Application of the method was demonstrated by the microscale identification of two conjugated triene and one conjugated diene components from extracts of the sex pheromone gland of the saturniid moth Automeris cecrops pamina.

Efficient method to locate double bond positions in conjugated trienes

The double bond positions of 11 conjugated trienes were unambiguously located through a simple derivatization method amenable to nanogram-scale analyses. The trienes were reacted with the powerful dienophile 4-methyl-1,2,4-triazoline-3,5-dione (MTAD), and the mass spectra of the resulting cycloadducts exhibited large diagnostic fragments which allowed the unequivocal location of the double bonds in the parent triene in most cases. Catalytic hydrogenation of the cycloadducts produced saturated compounds with characteristic mass spectral fragments from which the positions of the trienes in the parent compounds could be readily confirmed. Application of the method was demonstrated by the microscale identification of two conjugated triene and one conjugated diene components from extracts of the sex pheromone gland of the saturniid moth Automeris cecrops pamina.

A Diels–Alder approach for the synthesis of highly functionalized benzo-annulated indane-based α-amino acid derivatives via a sultine intermediate

The synthesis of various highly functionalized benzo-annulated indane-based α-amino acid (AAA) derivatives are reported via a [4+2] cycloaddition strategy using a sultine derivative, containing an AAA moiety, as a reactive diene component. By adopting this strategy, a new α,α-dialkylated indane-based C 60 fullerene containing a constrained AAA unit is reported.

The hetero Diels–Alder reaction featuring 2-phenyl-4-dimethylamino-1-thia-3-azabuta-1,3-diene as diene component: a clear example of a thermodynamically-controlled process

Cycloaddition reactions of diene 1a with various dienophiles lead to trans 4,5-disubstituted dihydro-1,3-thiazine adducts. We demonstrate that a thermodynamically-controlled process, in which the adduct N-3 nitrogen plays a prominent role, accounts for the observed trans relative configuration.

Electron spin resonance study on chemical crosslinking reaction mechanisms of polyethylene using a chemical agent. V. Comparison with polypropylene and ethylene‐propylene copolymer

We studied the chemical reaction process of polypropylene (PP), ethylene-propylene copolymer (EPM), and ethylene-propylene-diene copolymer (EPDM) crosslinking induced by dicumyl peroxide (DCP) using electron spin resonance (ESR). Free radicals appeared at an elevated temperature of around 120 °C and the behavior and kinetics of the reaction process were observed at 180 °C. The radical species detected in PP were alkyl type radicals, formed by the abstraction of hydrogen atoms from the tertiary carbon of polymer chains. For EPDM containing a diene component, the radicals were trapped at double bonds in this diene component to form allyl radicals. The resolutions of these spectra were extremely clear; hence, isotropic spectra of these polymer radicals were obtained. We measured the ESR at high temperatures and confirmed that the process of crosslinking induced by DCP was a free radical reaction. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3383–3389, 2000

Electron spin resonance study on chemical crosslinking reaction mechanisms of polyethylene using a chemical agent. V. Comparison with polypropylene and ethylene-propylene copolymer

We studied the chemical reaction process of polypropylene (PP), ethylene-propylene copolymer (EPM), and ethylene-propylene-diene copolymer (EPDM) crosslinking induced by dicumyl peroxide (DCP) using electron spin resonance (ESR). Free radicals appeared at an elevated temperature of around 120 °C and the behavior and kinetics of the reaction process were observed at 180 °C. The radical species detected in PP were alkyl type radicals, formed by the abstraction of hydrogen atoms from the tertiary carbon of polymer chains. For EPDM containing a diene component, the radicals were trapped at double bonds in this diene component to form allyl radicals. The resolutions of these spectra were extremely clear; hence, isotropic spectra of these polymer radicals were obtained. We measured the ESR at high temperatures and confirmed that the process of crosslinking induced by DCP was a free radical reaction. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3383–3389, 2000

On the Specificity of Reactions Catalysed by the Antibody H11

The substrate specificity and the stereochemical course of the reactions catalysed by the antibody H11 (which was raised to a protein conjugated derivative of the adduct of 1-acetoxy-buta-1,3-diene 1) have been investigated. The antibody shows high selectivity for acetoxybutadiene which it hydrolyses to the corresponding dienol, the major diene component of the cycloaddition reactions observed. However, it tolerates a range of N-alkylmaleimides. The stereochemical course of cycloaddition is shown to produce a significant enantiomeric excess of the 3a R, 4 S, 7a R- endo-diastereoisomer by analysis with Mosher's ester derivatives. This study also revealed that H11 is capable of slowly catalysing the hydrolysis of N-alkylmaleimide substrates. The implications for the mechanism of action of H11 are discussed.

ChemInform Abstract: Diethylaluminum Ethoxide Mediated Stereoselective Diels—Alder Reaction of α,β‐Unsaturated Ketones and Acetoxy‐1,3‐butadienes as Diene Components.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.