Reaction Of Furan Research Articles

A novel fluorinated monomer: Synthesis, characterization and ATRP of 5,6,7,8-tetrafluoronaphthalen-1-yl acrylate

A new fluorinated naphthyl-acrylate based monomer was synthesized in three steps, namely the addition reaction of furan via Diels Alder cycloaddition reaction, acid catalyzed aromatization reaction and Schotten-Baumann esterification reaction, respectively. The structure of the precursors and the target compound was characterized comprehensively by FT-IR, UV–vis, 1H NMR, 13C NMR, 19F NMR and LC–MS/MS measurements. Atom transfer radical polymerization (ATRP) was used for the polymerization of 5,6,7,8-tetrafluoronaphthalen-1-yl acrylate. The successful polymerization of this novel monomer was verified by FT-IR and GPC analyses. Particularly, DSC and TGA analyses showed that the poly(5,6,7,8-tetrafluoronaphthalen-1-yl acrylate) has a glass transition temperature of 105−110 °C and starts to degrade after 150 °C. The results showed that the proposed monomer can be synthesized in yields overpassing 80 % by using the aforementioned reaction sequence. Our results revealed that 5,6,7,8-tetrafluoro naphthalen-1-yl acrylate could be acceptable as a promising monomer candidate in the field of synthetic polymer chemistry.

Halogen Bond‐Catalyzed Friedel−Crafts Reactions of Furans Using a 2,2’‐Bipyridine‐Based Catalyst

AbstractA halogen bond donor based on a 2,2’‐bipyridine framework has been synthesized, and used to catalyze Friedel−Crafts reactions of furans. Electrophiles used successfully in these reactions included various enones, an aldehyde, and a carboxylic acid anhydride. The yields of the reactions were generally good using a moderate catalyst loading (0.025 or 0.1 equiv.) at a relatively low temperature (room temp. or 50 °C) in acetonitrile. The catalyst used was designed with a biaryl scaffold so that if it indeed proved to be an efficient halogen bond donor organocatalyst, an enantioenriched version of it could potentially serve as a stereoselective catalyst.magnified image

On the solvent‐ and temperature‐driven stereoselectivity of the Diels–Alder cycloaddition reactions of furan with maleic anhydride and maleimide

AbstractIn quantum chemical calculations, the Diels–Alder (DA) cycloaddition reaction of furan with maleic anhydride favors the endo‐isomer kinetically in the gas phase. This preference, however, changes in favor of the exo‐isomer on inclusion of solvent effects. For example, in acetonitrile, the exo‐isomer was calculated to form twice as fast as the endo‐isomer at room temperature, an observation that corroborates well with the experiments. The free energy change of the reaction is such that it allows faster reversal of the endo‐isomer to the reactants in an equilibrium process and, thus, the predominance of the more stable exo‐isomer eventually. The reaction of furan with maleimide is similar to that with maleic anhydride. However, it predominantly favors endo‐selectivity at temperatures below 320 K, which is also in excellent agreement with the experimental studies of temperature dependence of this DA reaction. Further, a gedanken calculation of the DA reaction of furan with cyclopropene has been investigated to delineate the effect of the retro‐pathway on stereoselectivity.

Development and Evaluation of a Detailed Mechanism for Gas-Phase Atmospheric Reactions of Furans

Furan and its alkyl derivatives (furans) are emitted to the atmosphere from multiple sources and can exist in sufficient quantities to affect atmospheric oxidant levels and secondary pollutant form...

Microwave Thermal Effect on Diels-Alder Reaction of Furan and Maleimide

Background: Higher temperature regions (hot spots) have been observed in organic reactions and are attributed to microwave selective heating. The accumulated heat in reaction systems accelerates certain reactions. Methods: The theoretical calculation was applied to select a suitable Diels-Alder reaction as a molecular probe to determine the microwave thermal effect on Diels-Alder reaction, one class of bimolecular reactions. The kinetic investigations were utilized to determine the reaction activation energies and further to calculate the actual reaction temperatures under different microwave conditions from the Arrhenius equation. Results: On the basis of the theoretical calculational results, Diels-Alder reaction of furan and maleimide was selected as a molecular probe to determine the microwave thermal effect in Diels- Alder reaction. Their activation energies under thermal conditions were determined from kinetic data by using the Arrhenius equation. The actual reaction temperatures under different microwave conditions were further deduced from their activation energies and the Arrhenius equation. Conclusion: Higher temperature regions (hot spots) were observed in Diels-Alder reaction, and they are more obvious in less polar solvents than those in more polar solvents in the microwave irradiated reactions.

Enhancing the aromatic hydrocarbon yield from the catalytic copyrolysis of xylan and LDPE with a dual-catalytic-stage combined CaO/HZSM-5 catalyst

The high concentration of oxygenated compounds in pyrolytic products prohibits the conversion of hemicellulose to important biofuels and chemicals via fast pyrolysis. Herein CaO and HZSM-5 was developed to convert xylan and LDPE to valuable hydrocarbons by thermogravimetric analysis (TGA) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and elucidate the reaction mechanism were also investigated in detail. The results indicated that xylan/LDPE copyrolysis was more complicated than pyrolysis of the individual components. LDPE hindered the thermal decomposition and aromatic hydrocarbon formation from xylan at temperatures under 350 °C and had a synergistic effect at high temperatures. 50% LDPE was proven to be more beneficial than other percentages for the formation of monocyclic aromatic hydrocarbons. Simultaneously, the addition of CaO/HZSM-5 significantly reduced the reaction Ea and increased the reaction rate. CaO can effectively improve the deoxygenation and aromatization reaction, enhancing the yield and selectivity of aromatics to a certain extent. The maximum yield of hydrocarbons (96.01%), mono-aromatic hydrocarbons (88.53%) and SBTXE (85.79%) were obtained at a CaO/HZSM-5 ratio of 1:2, a pyrolysis temperature of 450 °C, a catalytic temperature of 550 °C, a catalyst dose of 1:2 and a xylan-to-LDPE ratio of 1:1 via an ex situ process. The system was dominated by toluene, xylene and alkyl benzene. Diels-Alder reactions of furans and hydrocarbon pool mechanism of nonfuranic compounds improved aromatic formation. This study provides a fundamental for recovering energy and chemicals from pyrolysis of hemicellulose.

Iron-Catalysed C(sp2)-H Borylation Enabled by Carboxylate Activation.

Arene C(sp2)-H bond borylation reactions provide rapid and efficient routes to synthetically versatile boronic esters. While iridium catalysts are well established for this reaction, the discovery and development of methods using Earth-abundant alternatives is limited to just a few examples. Applying an in situ catalyst activation method using air-stable and easily handed reagents, the iron-catalysed C(sp2)-H borylation reactions of furans and thiophenes under blue light irradiation have been developed. Key reaction intermediates have been prepared and characterised, and suggest two mechanistic pathways are in action involving both C-H metallation and the formation of an iron boryl species.

Synthesis and biological evaluation of new chloro/acetoxy substituted isoindole analogues as new tyrosine kinase inhibitors.

We have developed a versatile synthetic approach for the synthesis of new isoindole derivatives via the cleavage of ethers from tricyclic imide skeleton compounds. An exo-cycloadduct prepared from the Diels-Alder reaction of furan and maleic anhydride furnished imide derivatives. The epoxide ring was opened with Ac2O or Ac2O/AcCl in the presence of a catalytic amount of H2SO4 in order to yield new isoindole derivatives 8a-d and 9a-d. The anticancer activity of these compounds was evaluated against the HeLa cell lines. The synthesized compounds showed inhibitory effects on the viability of HeLa cells and the degree of cytotoxicity was increased with the level of bigger branched isoindole derivatives. To better understand the acting mechanism of these molecules, western blot analysis was performed with using mTOR and its downstream substrates. In addition, human mTOR and ribozomal S6 kinase β1 (RS6Kβ1) have been investigated with molecular modelling studies as possible targets for compound series 8 and 9.

A First-Principles Investigation of Gas-Phase Ring-Opening Reaction of Furan over HZSM-5 and Ga-Substituted ZSM-5

The furan ring-opening reaction using three catalytic models, HZSM-5, the extra-framework sites [GaO]/ZSM-5, and [Ga(OH)2]/ZSM-5, was investigated using periodic density functional theory as a mode...

Asymmetric Vinylogous Mukaiyama‐Mannich Reactions of Heterocyclic Siloxy Dienes with Ellman's Fluorinated Aldimines

AbstractVinylogous Mukaiyama Mannich reactions of furan and pyrrole based dienoxy silanes with α‐fluoroalkyl sulfinyl imines provide a powerful synthetic access to a variety of amino fluoroalkyl γ‐butenolide‐type and butyrolactam frameworks with high regio‐ and diastereoselectivity. Anti‐configured adducts were obtained in all cases, independent of the nature of the heteroatom (O or N) present in the dienoxy silane. The absolute configuration of the adducts prepared was unequivocally established by X‐ray crystallographic analysis. It is noteworthy that the introduction of substituents at the γ‐position of the heterocyclic partner allows the generation of adducts bearing chiral quaternary centers.magnified image

Asymmetric Phosphoric Acid‐catalyzed Aza‐Friedel–Crafts Reaction of Furan with Cyclic N‐Sulfimines

Asymmetric Phosphoric Acid‐catalyzed Aza‐Friedel–Crafts Reaction of Furan with Cyclic <i>N</i>‐Sulfimines

Gold-Catalyzed Cascade Reactions of 4 H-Furo[3,2- b]indoles with Allenamides: Synthesis of Indolin-3-one Derivatives.

Merging the ability of cationic gold(I) catalysts to activate unsaturated π-systems with the electrophiles-driven ring-opening reactions of furans, we describe a new approach to synthesize 2-spiroindolin-3-ones from 4 H-furo[3,2- b]indoles. The reaction occurs through a cascade sequence involving addition of a gold-activated allene to the furan moiety of the starting furoindole followed by a ring-opening/ring-closing event affording 2-spirocyclopentane-1,2-dihydro-3 H-indolin-3-ones in moderate to good yields.

Mechanistic investigation of CO generation by pyrolysis of furan and its main derivatives.

A large amount of furan and its derivatives are contained in the biomass pyrolysis products, which mainly lead to the formation of combustible CO with an increase in the pyrolysis temperature; in this study, to illuminate the reaction mechanisms involved in the evolution of CO during the pyrolysis of furan and its main derivatives, quantum chemical theory has been adopted with the GGA-RPBE method, and nine possible reaction pathways have been investigated for the pyrolysis of furan, furfural (FF), furfuryl alcohol (FA) and 5-hydroxymethylfurfural (5-HMF) to generate CO. According to the calculation results, the optimal path for the pyrolysis of furan and its main derivatives to generate CO is as follows: at first, a ring opening reaction of furan occurs to form an aldehyde group, and then, decarbonylation occurs to form CO. Furthermore, the side chain functional groups on the furan ring can promote the ring opening reaction of the furan ring. In addition, the reaction energy barriers of the rate-determining step for the pyrolysis of furan, furfural, furfuryl alcohol and 5-hydroxymethylfurfural (5-HMF) to form CO have been determined as 343 kJ mol−1, 330 kJ mol−1, 317 kJ mol−1 and 363 kJ mol−1, respectively.

Total Synthesis of (±)-Prostratin

Summary Prostratin, a highly complex diterpene natural product, is a pre-clinical candidate in developing a cure for HIV-1 infection and also a potent and selective inhibitor of several tumors. Despite nearly 40 years of progress, prostratin and related natural products still present formidable challenges for synthetic chemists. Here, we report a total synthesis of (±)-prostratin that proceeds in 23 steps from cyclopentadiene. The synthetic strategy includes rapid assembly of the tricyclic core and highly controlled establishment of the densely functionalized C ring, featuring an array of stereoselective transformations including alkoxide-guided 1,4-additions and cyclopropane formation. This work should enable further explorations of chemical and biological spaces based on prostratin and related natural products.

Mechanistic study of silica-gel or FeCl3-promoted ring-opening aromatization of 7-oxanorborna-2,5-dienes affording 2-bromo-3-hydroxybenzoate derivatives

One-pot synthesis of 2-bromo-3-hydroxybenzoates by the Diels–Alder reaction of furans with bromoalkyne and the subsequent ring-opening aromatization was studied by means of deuterium-labeling experiments. The residual protons in silica gel were considered to be the hydrogen source of the hydroxy group of products under the silica gel-promoted condition. The deuterium-labeling experiment revealed a rapid equilibrium among the intermediates prior to the aromatization under FeCl3-catalyzed condition.

Synthetic Study toward the Total Synthesis of Taxezopidines A and B.

A concise synthetic approach to construct the [6,8,6]-tricyclic core of taxezopidines A and B, which contains a synthetically challenging bridged bicyclo[5.3.1]undecane ring system bearing most of the desired functionalized groups and stereocenters, has been established. This approach features a diastereoselective type II intramolecular Diels-Alder furan reaction. The stereochemistry of the acetoxy group at the allylic position of the dienophile alkene group, such as in 6a, was found to be critical for achieving the desired highly diastereoselective outcome.

Cure behaviors of furfuryl alcohol/epoxy/methyltetrahydrophthalic anhydride and their enhanced mechanical and anti-acid properties of basalt fiber reinforced composites

Catalyzing furfuryl alcohol and epoxy simultaneously with a suitable catalyst plays a key role in the preparation of high-performance blends. Herein, methyltetrahydrophthalic anhydride was utilized to cure furfuryl alcohol/epoxy resins, which reacted with epoxy firstly, then catalyzed the furan reaction and also linked furfuryl alcohol and epoxy. Moreover, partly ring-opened furan further catalyzed the curing reaction of epoxy. The addition content of methyltetrahydrophthalic anhydride affected the curing behaviors of furfuryl alcohol/epoxy blends, and their Tg and char yield at 700 °C reached the maxima of 140 °C and 16.79% respectively as the content increased to 50%. The mechanical and anti-acid properties of basalt fiber-reinforced composites were further studied. The mechanical properties of composites changed identically to those of the matrix did. Furfuryl alcohol improved the acid resistance of composites, probably because furan could be cured in acidic condition and basalt fiber was resistant to acid. All these changes were related to the curing mechanism and crosslinking density of furan/epoxy/methyltetrahydrophthalic anhydride blends.

Mechanistic and kinetic study on the reaction of Furan with O(3 P)

Mechanistic and kinetic study on the reaction of Furan with O(³ P)

Segmented catalytic co-pyrolysis of biomass and high-density polyethylene for aromatics production with MgCl2 and HZSM-5

For the catalytic co-pyrolysis of glucose and high-density polyethylene (HDPE) in a fixed-bed reactor, the effects of different layout schemes of feedstock and catalysts on bio-oil yield and aromatics selectivity were investigated based on the Diels-Alder reaction of furans and short-chain olefins on HZSM-5 for aromatics production. Experimental results showed that the arrangement (HDPE/HZSM-5/glucose/HZSM-5) had advantages on bio-oil yield and aromatics selectivity. A mixture of pine sawdust and MgCl2 as a glucose substitute that provided furan compounds (Furfural) reacted with short-chain olefins for aromatics production. We found that acquiring high selectivity of aromatic bio-oil from the catalytic co-pyrolysis of pine sawdust and HDPE with MgCl2 and HZSM-5 is feasible. The effects of co-pyrolysis temperature, biomass to HDPE ratio, and feedstock to catalyst ratio on bio-oil yield and chemical compositions were discussed. Notably, an appropriate ratio between the amounts of furans and short-chain olefins is necessary for increasing bio-oil yield and aromatics selectivity. Maximum oil phase product yield of 20.6% and aromatics selectivity (area %) of 95.9% were obtained when pyrolysis temperature, biomass to HDPE ratio, and feedstock to catalyst ratio were 600 ℃, 1:2, and 1:1, respectively.

The Aqueous Barbier Polycondensation of Biomass‐Derived 5‐Chloromethylfurfural: A Proof of Concept Study to Access Functional Polymers

AbstractThe versatility of the zinc‐mediated aqueous Barbier reaction in functional polymer synthesis is demonstrated in instance of a biomass‐derived bifunctional monomer, 5‐chloromethylfurfural (CMF). CMF is a renewable furan derivative that can be directly obtained from various sugars and cellulose in high yields and is a versatile precursor that can be converted into several valuable building blocks. In this study, CMF is utilized as a monomer in metal‐catalyzed conditions to access both furan and hydroxyl functional polymers. The effect of different reaction conditions on polymerization is explored. Polymers through Barbier polycondensation of bifunctional monomer are obtained with moderately good polymer conversions (54–89%) and molecular weights (8.7–15.1 kDa). The crosslinking of obtained functional polymers is studied by employing bismaleimide and dianhydride crosslinkers for possible application of synthesized polymers as hydrophilically modified membrane materials. The crosslinked materials are obtained by reaction of furan and alcohol groups through Diels–Alder and ester formation reactions, respectively. Synthesis and characterization procedures of linear and crosslinked polymers are described. The reported proof of concept study demonstrates the efficiency of aqueous Barbier reaction in functional polymer synthesis.