Furyl Groups Research Articles

1,2-Silyl Rearrangement in Gold Carbene Chemistry: Synthesis of Furyl-Decorated Tetrasubstituted Silylallene Derivatives.

The gold-catalyzed reaction of 2-en-4-ynones with alkynylsilanes provides fully substituted allene derivatives bearing furyl and silyl groups. This transformation would involve generation of a gold furyl carbene intermediate, which regioselectively undergoes a nucleophilic attack by the alkynylsilane at the electrophilic carbene carbon atom with the formation of a β-gold vinyl cation species. The subsequent release of the gold catalyst, accompanied by a 1,2-silyl shift, leads to the formation of tetrasubstituted allene products.

Pincer Nickel-Catalyzed Olefination of Alcohols with Benzylphosphine Oxides.

N,N,P-Pincer nickel complexes effectively catalyze reaction of alcohols with benzylphosphine oxides to form alkenes in good yields. The protocol suits for a wide scope of substrates and generates only E-configurated alkenes. The method also shows good compatibility of functional groups. Methoxy, methylthio, trifluoromethyl, ketal, fluoro, chloro, bromo, thienyl, and furyl groups are tolerated. The mechanism studies support that the reaction proceeds through catalytic dehydrogenation of alcohols to aldehydes or ketones followed by condensation with benzyldiphenylphosphine oxides in the presence of KOtBu.

Rational design of type-I photosensitizer molecules for mitochondrion-targeted photodynamic therapy.

Photodynamic therapy (PDT) has emerged as a promising approach for tumor treatment. However, traditional type II PDT faces limitations due to its oxygen-dependent nature. Type-I photosensitizers (PSs) exhibit superiority over conventional type-II PSs owing to their diminished oxygen dependence. Nevertheless, designing effective type-I PSs remains a significant challenge. In this work, we provide a novel strategy to tune the PDT mechanism of an excited photosensitizer through aryl substituent engineering. Using S-rhodamine as the base structure, three PSs were synthesized by incorporating phenyl, furyl, or thienyl groups at the meso position. Interestingly, furyl- or thienyl-substituted S-rhodamine are type-I-dominated PSs that produce O2˙-, while phenyl S-rhodamine results in O2˙- and 1O2 through type-I and type-II mechanisms, respectively. Experimental analyses and theoretical calculations showed that the introduction of a five-membered heterocycle at the meso position promoted intersystem crossing (ISC) and electron transfer, facilitating the production of O2˙-. Furthermore, furyl- or thienyl-substituted S-rhodamine exhibited high phototoxicity at ultralow concentrations. Thienyl-substituted S-rhodamine showed promising PDT efficacy against hypoxic solid tumors. This innovative strategy provides an alternative approach to developing new type-I PSs without the necessity for creating entirely new skeletons.

The effect of different cyclic substituents on the properties of recyclable acetal-containing epoxy resins

Vitrimers represent an emerging field warranting comprehensive investigation into fundamental aspects of dynamic covalent bond design. Herein, three acetal-containing cycloaliphatic epoxides (ACEs) with different cyclic substituents (cyclopentyl, furyl, and phenyl groups) were synthesized. These three liquid ACEs have different viscosities and refractive indices. After curing with anhydride, the cured ACEs show elevated glass transition temperature of up to 189 °C, and superior tensile strengths of up to 71 MPa. Interestingly, the dangling groups attached to the acetal bonds have a significant impact on the structure dynamics, reprocessability, degradation rates and hot wet aging resistance of cured ACEs. The effect of different dangling groups on the dynamic behaviors of acetal bonds was verified by small molecular modeling reactions. Among them, the epoxy resin containing the furyl group shows the fastest stress relaxation rate at the same temperature. The epoxy resin containing the phenyl group has the highest retention of tensile strength after reprocessing or hot wet aging, while the epoxy resin containing the cyclopentyl group exhibits the fastest degradation rate in various acid solutions. These cured ACEs can also be effectively repaired and welded owing to their dynamic structures. These noteworthy discoveries provide essential insights for understanding the structure-property relationship of acetal-containing recyclable thermosetting polymers.

Rapid Reassembly, Biomass-Derived Adhesive Based on Soybean Oil and Diels-Alder Bonds.

Synthetic adhesives play a crucial role in holding together solid materials through interfacial interactions. Thermoplastic and thermosetting adhesives are important types of synthetic adhesives, with thermoplastic adhesives being reassemblable and thermosetting adhesives exhibiting high adhesive strength and creep resistance. However, there is a need to combine the advantages of both types and develop high bonding strength, reassemblable adhesives. Here, epoxidized soybean oil (ESO) was used to prepare adhesive networks and Diels-Alder bonds were incorporated to enhance reassembly ability. The ESO was functionalized with furyl groups and cross-linked via the reaction between furyl and imide groups to involve the Diels-Alder bonds. The resulting adhesive exhibited good solvent resistance and mechanical properties, which could be regulated by adjusting the quantity of cross-linker. The prepared adhesives also demonstrated self-healing capabilities, as the scratch on the surface gradually diminished with heating. Additionally, the adhesives showed the ability to undergo recycling without significant changes in properties. The prepared adhesives exhibited hydrophilicity and the flow characteristics during reassembly were characterized by a decrease in torque. This study provides a promising approach for the development of synthetic adhesives with reassembly ability, which has important implications for the field of bonding.

Reprocessable polyhydroxyurethane networks crosslinked with trifunctional polyhedral oligomeric silsesquioxanes via Diels-Alder reaction

In this contribution, we reported the polyhydroxyurethane (PHU) networks crosslinked with trifunctional polyhedral oligomeric silsesquixanes (POSS) via Diels-Alder (D-A) reaction. First, a linear PHU was synthesized via the step-growth polymerization of a difunctional six-membered bicyclic carbonate (6BCC) with an α,ω-diamino-terminated polytetrahydrofuran (NH2-PTHF-NH2) as well as 2,5-diaminomethylfuran. Second, an incompletely-condensed POSS macromer carrying three maleimido groups was synthesized via the multiple reactions involving silylation, Heck and imidization. The linear PHU was crosslinked with the POSS macromer via the D-A reaction of furyl groups in the main chain of PHU with maleimido groups of the POSS macromer. The morphological investigation showed that the PHU-POSS networks displayed the microphase-separated nanostructures, in which the POSS cages were self-assembled into the spherical aggregates with the diameter of 20–30 nm. Compared to the linear PHU, the PHU-POSS networks displayed the improved thermomechanical properties. Thanks to the introduction of D-A linkages, more importantly, the networks possessed the excellent recycling (or reprocessing) and reconfigurable shape memory properties.

Di-indenopyridines as topoisomerase II-selective anticancer agents: Design, synthesis, and structure–activity relationships

Topoisomerases are key molecular enzymes responsible for altering DNA topology, thus they have long been considered as attractive targets for novel chemotherapeutic agents. Topoisomerase type II (Topo II) catalytic inhibitors embrace a fresh perspective meant to get beyond drawbacks caused by topo II poisons, such as cardiotoxicity and secondary malignancies. Based on previously reported 5H-indeno[1,2-b]pyridines, here we presented new twenty-three hybrid di-indenopyridines along with their topo I/IIα inhibitory and antiproliferative activity. Most of the prepared 11-phenyl-diindenopyridines showed negligible topo I inhibitory activity, showing selectivity over topo II. Among the series, we finally selected compound 17, which displayed 100 % topo IIα inhibition at 20 μM concentration and comparable antiproliferative activity against the tested cell lines. Through competitive EtBr displacement assay, cleavable complex assay, and comet assay, compound 17 was finally determined as a non-intercalative catalytic topo IIα inhibitor. The findings in this study highlight the significance of phenolic, halophenyl, thienyl, and furyl groups at the 4-position of the indane ring in the design and synthesis of di-indenopyridines as potent catalytic topo IIα inhibitors with remarkable anticancer effects.

Synthesis and structure-activity relationship of new nicotinamide phosphoribosyltransferase inhibitors with antitumor activity on solid and haematological cancer

Cancer cells are highly dependent on Nicotinamide phosphoribosyltransferase (NAMPT) activity for proliferation, therefore NAMPT represents an interesting target for the development of anti-cancer drugs. Several compounds, such as FK866 and CHS828, were identified as potent NAMPT inhibitors with strong anti-cancer activity, although none of them reached the late stages of clinical trials. We present herein the preparation of three libraries of new inhibitors containing (pyridin-3-yl)triazole, (pyridin-3-yl)thiourea and (pyridin-3/4-yl)cyanoguanidine as cap/connecting unit and a furyl group at the tail position of the compound. Antiproliferative activity in vitro was evaluated on a panel of solid and haematological cancer cell lines and most of the synthesized compounds showed nanomolar or sub-nanomolar cytotoxic activity in MiaPaCa-2 (pancreatic cancer), ML2 (acute myeloid leukemia), JRKT (acute lymphobalistic leukemia), NMLW (Burkitt lymphoma), RPMI8226 (multiple myeloma) and NB4 (acute myeloid leukemia), with lower IC50 values than those reported for FK866. Notably, compounds 35a, 39a and 47 showed cytotoxic activity against ML2 with IC50 = 18, 46 and 49 pM, and IC50 towards MiaPaCa-2 of 0.005, 0.455 and 2.81 nM, respectively. Moreover, their role on the NAD+ synthetic pathway was demonstrated by the NAMPT inhibition assay. Finally, the intracellular NAD+ depletion was confirmed in vitro to induced ROS accumulation that cause a time-dependent mitochondrial membrane depolarization, leading to ATP loss and cell death.

Photophysical properties of furan-bridged dimeric boron-dipyrromethene derivatives (BODIPYs)

In order to investigate the changes in the spectroscopic properties of dimeric boron-dipyrromethenes (BODIPYs), four BODIPY derivatives are synthesized, including a monomer BODIPY in which a furyl group is substituted at the meso position and a dimer BODIPY with a furan group as a bridge. The four synthesized BODIPY derivatives are characterized through nuclear magnetic resonance and mass spectrometry. Photophysical properties such as ultraviolet–visible absorbance and the fluorescence emission of monomers (mT1 and mT2) and dimers (biT1 and biT2) are studied in eight different solvents. In addition, the relationship of their structural properties and optical properties are also considered through density functional theory calculations. The covalent link between the two BODIPY units using a furan group has a profound effect on the optical properties of the dimeric BODIPYs. We believe that an understanding of the synthesis and physical properties of dimeric BODIPYs will have a promising perspective in designing new BODIPY derivatives and predicting their spectroscopic characteristics in the future.

Molecular Tuning in Diaryl-Capped Pyrrolo[2,3-d:5,4-d']bisthiazoles: Effects of Terminal Aryl Unit and Comparison to Dithieno[3,2-b:2',3'-d]pyrrole Analogues.

A series of six conjugated oligomers consisting of a central pyrrolo[2,3-d:5,4-d′]bisthiazole (PBTz) end-capped with either thienyl, furyl, or phenyl groups have been prepared from N-alkyl-and N-aryl-pyrrolo[2,3-d:5,4-d′]bisthiazoles via Stille and Negishi cross-coupling. The full oligomeric series was thoroughly investigated via photophysical and electrochemical studies, in parallel with density functional theory (DFT) calculations, in order to correlate the cumulative effects of both aryl end-groups and N-functionalization on the resulting optical and electronic properties. Through comparison with the analogous dithieno[3,2-b:2′,3′-d]pyrrole (DTP) materials, the effect of replacing DTP with PBTz on the material HOMO energy and visible light absorption is quantified.

Substituent effects on the stretching vibration frequencies of C=C bridge bond in aryl ethylene with furyl or thienyl group

AbstractTo explore the substituent effects on the stretching vibration frequencies νC=C of C=C bridge bond in 1‐furyl/thienyl‐2‐aryl ethylene XCH=CHArYs, 60 samples of XCH=CHArYs were synthesized, and their infrared absorption spectra were recorded. The regression analyses between the νC=C values of XCH=CHArYs and the substituent parameters of X and Y were made in detail. Finally, an optimality equation (shown as Equation 3) quantifying the νC=C values of XCH=CHArYs was obtained. It shows that the substituent effects on the νC=C values of XCH=CHArYs mainly reflect in Hammett constant of X and the excited‐state substituent constants of X and Y. Among the parameters in Equation (3), the excited‐state substituent constant of X contributes the most to the νC=C values of XCH=CHArYs as seen from the fraction contributions. On the whole, the contribution of X to the νC=C values of XCH=CHArYs is larger than that of Y.

Ethynyl and Furyl Functionalized Porphyrin Complexes as New Organic Cathodes Enabling High Power Density and Long-Term Cycling Stability.

Organic cathode materials have recently attracted abundant attention due to their flexible structural tunability and recyclability. However, the low intrinsic electrical conductivity and high solubility in electrolytes of organic electrode materials have significantly limited their practical application. Herein, we present [5,15-bis(ethynyl)-10,20-difurylporphinato] copper(II) (CuDEOP) as a new cathode for rechargeable organic lithium batteries (ROLBs). The combination of both ethynyl and furyl groups of the CuDEOP cathode with a nanorod structure renders it with enhanced structural stability and an extended delocalized π-electron system to deliver excellent cycling stability (capacity retention of 76% after 6000 cycles) and a high power density (16 kW kg-1). The furyl electroactive groups participate in charge storage contribution to achieve a reversible six-electron-transfer redox reaction in a specific voltage range. The mechanism characterizations indicate that the nitrogen atoms on the porphyrin ring act as active sites to alternatively store both PF6- anions and Li+ cations, and the charge storage process is a pseudocapacitive-dominated reaction. This observation will offer a new avenue for designing functionalized molecules for electrochemical energy-storage (EES) systems.

Effect of Meso-Thienyl and Meso-Furyl Groups on the Electronic Properties of Aromatic 14π Triphyrin(2.1.1)s.

A series of triphyrin(2.1.1)s containing five membered heterocycles such as thienyl and furyl groups in place of six membered aryl groups at two or four meso-positions were synthesized by [2+1] condensation of appropriate dipyrroethene diols with pyrrole under acid catalyzed conditions. The meso-thienyl and meso-furyl triphyrin(2.1.1)s were characterized and studied by HR-MS, 1D & 2D NMR spectroscopy, X-ray crystallography, absorption, cyclic voltammetry and DFT/TD-DFT studies. The X-ray structure obtained for one of the meso-thienyl trirphyrins indicated that the macrocycle was nearly planar and showed strong intramolecular hydrogen bonding. The spectral and electrochemical studies revealed that in meso-thienyl and meso-furyl triphyrin(2.1.1)s, the resonances of triphyrin core protons downfield shifted in 1 H NMR, the absorption bands bathochromically shifted and redox potentials shifted cathodically and anodically compared to meso-tetra(p-tolyl) triphyrin(2.1.1). These observations indicated that the thienyl/furyl groups at meso-positions alter the electronic properties of triphyrin(2.1.1)s significantly and the maximum effects were noted in meso-tetra(2-thienyl) triphyrin(2.1.1) and meso-tetra(2-furyl) triphyrin(2.1.1)s. The DFT and TD-DFT studies corroborated experimental observations.

Novel Galactosyl Moiety-Conjugated Furylchalcones Synthesized Facilely Display Significant Regulatory Effect on Plant Growth.

The expansion of weed infestation has increased the demand on new herbicides. A series of novel galactosyl moiety-conjugated furylchalcones was facilely synthesized in which the furyl group (A ring) was combined with the substituted benzene group (B ring), and a galactosyl moiety was introduced. All these galactosyl furylchalcones were predicted to be phloem-mobile. Most of the galactosyl furylchalcones significantly promoted early seedling growth of sorghum and barnyardgrass under dark conditions, but all of them revealed considerable anti-growth ability on illuminated pot plants; especially, 1-(3'-(4″-O-β-d-galactopyranosyl)furyl)-3-(4″-nitrophenyl)-2-en-1-one (B11) had a better herbicidal activity against rapeseed and Chinese amaranth than haloxyfop-R-methyl. The median efficient concentrations (EC50) of compound B11 against cucumber and wheat were 9.55 and 26.97 mg/L, respectively, also showing a stronger suppressing capacity than 2,4-D. Molecular docking with phosphoenolpyruvate carboxylase protein showed a stable binding conformation in which the galactosyl group interacted with LYS363 and GLU369, the furan ring and carbonyl bound with ARG184, and the crosslink of the nitro group with GLU240 formed a salt bridge. The results demonstrate that galactosyl furylchalcones possess the great potential as new herbicides for weed management, and further evaluations on more weeds are required for practical application.

Simulation and analysis of the relaxation dynamics of a photochromic furylfulgide.

Furylfulgides, a class of photochromic organic compounds, show a complex system of photoinduced reactions. In the present study, the excited-state dynamics of the Eα and Eβ isomers of a representative furylfulgide is modelled with the use of nonadiabatic molecular dynamics simulations. Moreover, a pattern recognition algorithm is employed in order to automatically identify relaxation pathways, and to quantify the photoproduct distributions. The simulation results indicate that, despite differing only in the orientation of the furyl group, the two isomers show markedly different photochemical behaviour. The predominant Eα isomer undergoes photocyclisation with a quantum yield (QY) of 0.27 ± 0.10. For this isomer, the undesired E → Z photoisomerisation around the central double bond represents a minor side reaction, with a QY of 0.09 ± 0.07. In contrast, the minority Eβ isomer, which is incapable of photocyclisation, undergoes efficient E → Z photoisomerisation, with a QY as high as 0.56 ± 0.14. The relaxation kinetics and the photoproduct distributions are interpreted in the light of the available experimental data.

Enhancing the Photoelectric Properties of Zinc Porphyrin Dyes by Introducing Five-Membered Heterocyclic Rings into the Electron Donor: A Density Functional Theory and Time-Dependent Density Functional Theory Study.

To fabricate highly efficient dye sensitizers for dye-sensitized solar cells, new zinc porphyrin dye sensitizers were designed based on one of the most efficient dyes, YD2-o-C8, by introducing electron-rich heterocyclic rings into the electron donor. Five potentially efficient dyes, Dye1–5, were obtained by replacing the phenyl group of the donor in YD2-o-C8 with pyrrolyl, furyl, and thienyl groups. The electronic structures, absorption spectra, intramolecular charge-transfer characteristics, and excited-state lifetimes of the designed dyes were investigated using the density functional theory and time-dependent density functional theory methods. All the designed dyes exhibit better photoelectric properties than those of YD2-o-C8. Compared with YD2-o-C8, the designed new dyes have smaller frontier molecular orbital energy gaps and obvious red-shifting absorption spectra in the Q band. The analyses of charge density difference plots and intramolecular charge-transfer characteristics indicated that the designed dyes can better promote intramolecular charge transfer and electron–hole separation. Among the five designed dyes, Dye1 with a pyrrolyl group exhibits the best performance. Dye3 and Dye5 with methyl-furyl and methyl-thienyl groups, respectively, exhibit the next best performance. Dye2 and Dye4 with furyl and thienyl groups, respectively, are the worst performers. The introduced methyl group can further improve the electron-donating ability of heterocyclic rings and promote the red shift of the Q bands and intramolecular charge transfer of dyes. The excited-state lifetimes of the new dyes were in the following order: YD2-o-C8 < Dye4 < Dye2 < Dye5 < Dye3 < Dye1, which shows their stronger abilities to inject electrons into semiconductor films.

Partially bio‐based furyl‐functionalized organosoluble poly(ether ether ketone)s

AbstractA new series of partially bio‐based (co)poly(ether ether ketone)s bearing pendent furyl groups was synthesized by nucleophilic aromatic substitution polycondensation of varying molar proportions of 4,4′‐(furan‐2‐ylmethylene)bis(2‐methoxyphenol) and bisphenol‐A with 4,4′‐difluorobenzophenone. The chemical structures, compositions and random nature of (co)poly(ether ether ketone)s were confirmed by NMR spectroscopy. Inherent viscosities and number‐average molecular weights of the (co)poly(ether ether ketone)s were in the range 0.74–2.90 dL g−1 and 33 500–46 300 g mol−1, respectively, indicating the formation of reasonably high molecular weight polymers. (Co)poly(ether ether ketone)s were readily soluble in common organic solvents and could be cast into tough, transparent and flexible films from chloroform solutions. (Co)poly(ether ether ketone)s exhibited 10% weight loss and glass transition temperatures in the range 429–464 and 152–156 °C, respectively. A representative copoly(ether ether ketone) was crosslinked with 1,1′‐(methylenedi‐1,4‐phenylene)bismaleimide via Diels–Alder reaction to form a crosslinked polymer which showed improved mechanical properties and was recycled twice without significant loss of mechanical properties. Diels–Alder/retro Diels–Alder reaction was demonstrated by studies of sol–gel transformation, solubility tests, DSC and stress–strain measurements. © 2020 Society of Chemical Industry

Radical-Mediated Hetaryl Functionalization of Nonactivated Alkenes through Distal ipso-Migration of O- or S-Hetaryls

AbstractA radical-mediated hetaryl functionalization of nonactivated alkenes through distal ipso-migration of O- or S-containing hetaryls was developed. Furyl, benzofuryl, thienyl, and benzothienyl groups showed satisfactory migratory abilities. A variety of heteroatom-centered radicals, including azido, trifluoromethylsulfanyl, and silyl radicals readily trigger the migration cascade, and a new C–heteroatom and C–C bond are concomitantly constructed in the reaction. This method provides an efficient approach to the synthesis of high-valued complex O- or S-hetaryl compounds.

Chiral Cobalt(II) Complex Catalyzed Asymmetric [2,3]-Sigmatropic Rearrangement of Allylic Selenides with α-Diazo Pyrazoleamides

Organoselenium compounds, due to their high structural diversity, special function, and biological activities, have drawn attention in synthetic chemistry. Herein, a novel example of chiral N,N′-di...

Photochromism and Fluorescence Switch of Furan-Containing Tetraarylethene Luminogens with Aggregation-Induced Emission for Photocontrolled Interface-Involved Applications.

It is extremely challenging to design photocontrolled molecular switches with absorption and fluorescence dual-mode outputs that are suited for a solid surface and interface. Herein, we report a group of furan-containing tetraarylethene derivatives with unique photophysical behavior of aggregation-induced emission (AIE) and distinct photochemical reaction-triggered photochromic behaviors by combining a photoactive furan or benzofuran group and an AIE-active triphenylethene molecule. The introduction of a furyl or benzofuryl group into the AIE luminogen endows the molecules with significant reversible photochromism and solid-state fluorescence. The coloration and decoloration of these molecules can be switched by respective irradiation of UV and visible light in a reversible way, and the photochromic changes are accompanied by a switch-on and switch-off of the solid-state fluorescence. It is revealed that the photocontrolled cyclization and cycloreversion reactions are responsible for the reversible photochromism and fluorescence switching based on experimental data and theoretical analysis. Both the position and conjugation of the introduced photoactive units have significant influence on the color and strength of the photochromism, and the simultaneous occurrence of photoinduced fluorescence change in the solid state is perfectly suited for surface-involved applications. The demonstrations of dual-mode signaling in photoswitchable patterning on a filter paper and anti-counterfeiting of an anti-falsification paper strongly highlight the unique advantage of these photochromic molecules with an aggregation-induced emission characteristic in various practical applications. This work proposes a general strategy to design photochromic molecules with AIE activity by introducing photoactive functionals into an AIEgen and demonstrates incomparable advantage in dual-mode signaling and multifunctional applications of these molecules.