Allyl Ethers Research Articles

Enantioselective Synthesis of Alkyl Allyl Ethers via Palladium-Catalyzed Redox-Relay Heck Alkenylation of O-Alkyl Enol Ethers.

Herein we report a transformation that generates an array of enantiomerically enriched, alkyl allyl ethers. Cyclic, acyclic, and heteroatom-bearing alkenyl triflates undergo an enantioselective, palladium-catalyzed C-C bond formation with diverse acyclic O-alkyl enol ethers in good yields and excellent enantioselectivities.

Rapid detection of CO in vitro and in vivo with a ratiometric probe showing near-infrared turn-on fluorescence, large Stokes shift, and high signal-to-noise ratio

A new near-infrared (NIR) fluorescent probe was developed for the detection of CO in living systems. This probe is based on a unique cyanine fluorophore and uses an allyl ether moiety as the reaction site. Optical studies in solution show that this probe has good water solubility and possesses desirable sensing properties for CO including rapid response, high selectivity and sensitivity, large Stokes shift (123 nm), distinct colorimetric changes, and significant turn-on NIR fluorescence changes at 715 nm with high signal-to-noise ratio. Ratiometric fluorescent detection of CO with this probe at 715 and 570 nm is also applicable. The sensing mechanism was proven to be a process of recovery of the fluorophore by removing the allyl group via Tsuji-Trost reaction. Furthermore, this probe was applied for detecting CO in living cells and animals with good bioimaging performance. Moreover, indicated by this probe, more CO could be produced under oxidative stress conditions. All the results indicate that this probe can be applied as a promising new tool for in vitro and in vivo detection of CO.

Photochemical Behavior of Allyl ethers of Vicinal Hydroxynaphthophenones

In this research work, hitherto unreported photochemical studies on allyl ethers of 1-hydroxy-2-naphthophenone, 2-hydroxy-1-naphthophenone and 3-hydroxy-2-naphthophenone are presented. While allyl ethers of 1-hydroxy-2-naphthophenone were photoactive at 330 nm and the other two ethers were photostable

Palladium/Benzoic Acid-Catalyzed Regio- and Stereoselective Polymerization of Internal Diynes and Diols through C(sp3)-H Activation.

The C-H activation has been a hot research area in organic chemistry, and the most difficult one is the C(sp3)-H activation. Although the C-H activation has been introduced to the research of synthetic polymer chemistry, the polymerization developed based on C(sp3)-H activation is rarely reported, which will enrich the tools for the preparation of functional polymers. In this work, palladium/benzoic acid catalyzed polymerization of internal diynes and diols through C(sp3)-H activation was successfully established. Regio- and stereoregular functional poly(allylic ether)s with 100% E-isomers and high weight average molecular weights (Mw up to 33200) were prepared in excellent yield (98%). The reaction mechanism was unveiled with the assistance of density functional theory calculations. Furthermore, the thin films of polymers display high refractive indices and low optical dispersions. The polymer containing tetraphenylethene moiety displays the aggregation-enhanced emission feature and could be used to generate 2D fluorescent photopattern. Thus, this work not only establishes a powerful polymerization based on C(sp3)-H activation, but also furnishes functional polymers for diverse applications.

Highly branched phenolic resin‐grafted silicone rubber copolymer for high efficiency ablation thermal protection coating

ABSTRACTHighly branched phenolic resin‐grafted silicone rubber (PGS) was synthesized by grafting allyl ether phenolic resin onto silicone rubber with Si─H groups via hydrosilylation. The chemical structure of the copolymer was characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and gel permeation chromatography, and its microphase morphology was observed via scanning electron microscopy (SEM). The mechanical properties and thermal stability of the material were also characterized. Thereafter, an ablation thermal protection coating (ATPC) based on PGS as the polymer matrix was prepared. In comparison with silicone rubber‐based ATPC, the PGS‐based ATPC showed better thermal stability and a stronger char layer. After oxygen–acetylene testing, the micromorphology and chemical composition of the PGS‐based ATPC were characterized via SEM, energy‐dispersive spectrometry, and X‐ray diffraction. Finally, the PGS‐ and silicone rubber‐based ATPCs were subjected to a heat flow of 370 kW m−2 for 70 s, the background temperature of the PGS‐based ATPC was only 70 °C. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48353.

Zwitterionic amino acid-based Poly(ester urea)s suppress adhesion formation in a rat intra-abdominal cecal abrasion model

Hernia repair outcomes have improved with more robust material options for surgeons and optimized surgical techniques. However, ventral hernia repairs remain challenging with an inherent risk of post-surgical adhesions in the peritoneal space which can occur regardless of interventional material or its surgical placement. Herein, amino acid-based poly(ester urea)s (PEUs) with varied amount of an allyl ether side chains were modified post polymerization modification with the zwitterionic sulfnate group (3-((3-((3-mercaptopropanoyl)oxy)propyl) dimethylammonio)propane-1-sulfonate) to promote anti-adhesive properties. These alloc-PEUs were processed using roll-to-roll fabrication methods to afford films that were amenable to surface functionalization via a zwitterion-thiol. Functional group availability on the surface was confirmed via fluorescence microscopy, x-ray photoelectron spectroscopy (XPS), and quartz crystal microbalance (QCM) measurements. Zwitterionic treated PEUs exhibited reduced fibrinogen adsorption in vitro when compared to unfunctionalized control polymer. A rat intrabdominal cecal abrasion adhesion model was used to assess the extent and tenacity of adhesion formation in the presence of the PEUs. The 10% alloc-PEU zwitterion functionalized material was found to reduce the extent and tenacity of adhesions when compared to adhesion controls and the unfunctionalized PEU controls.

A Modified Cationic Mechanism for PdCl2-Catalyzed Transformation of a Homoallylic Alcohol to an Allyl Ether

Density functional theory calculations were utilized to investigate a PdCl2-catalyzed transformation involving double-bond migration (alkene isomerization), followed by condensation with methanol s...

Rational design of stable near-infrared cyanine-based probe with remarkable large Stokes Shift for monitoring Carbon monoxide in living cells and in vivo

Carbon monoxide (CO) is an important kind of gasotransmitter associated closely with pathogenesis of inflammation and detection of CO in living systems is of great attraction in recent years. To data, accurate fluorescent detection of CO in vivo is still challenging. In this study, we reported for a new simple NIR fluorescent probe CO–B with stable allyl ether as the specific CO-reactive site. The detection mechanism of this probe has been proven through the rearrangement of conjugated π-electron system. CO–B featured large Stokes shift (135 nm), low toxicity, good sensitivity (detection limit of ∼110 nM) and selectivity for CO detection. CO–B successfully served as an indicator for imaging CO in Heme-stimulation inflammation model. Finally, CO–B was also employed for in vivo imaging CO in living mice with low background interference. All together, probe CO–B was potentially valuable as a promising tool for monitoring and tracking CO in preclinical applications.

Research of N,N-diallyl (3-arylisoxasol-5-yl)-methylenesulfonylamides as additives for increasing the load carryng capacity of syntetic oil based on the pentaerythritol esther and butyric acid

The object of research is N,N-diallyl (3-arylisoxasol-5-yl)-methylenesulfonylamides (Ar: C6H5 (1); C6H4–4–CH3 (2); C6H4–4–OC2H5 (3)) as antiwear additives to oils that are derived from the corresponding sulfonyl chloride and dialylamine. The industrial additive DF-11 (zinc dialkyldithiophosphate) (4) was used as a reference in action, and the 2-mercaptobenzthiazole allyl ether was used as a structural standard (5). As a synthetic oil, pentaerythritol and n-butyric acid ester, which is obtained by the esterification reaction, is used.Some physical characteristics (relative viscosity and refractive index) of the obtained oil were studied with and without the addition of sulfonylamides (1)–(3).The effect of the addition of N, N-diallyl (3-arylisoxasol-5-yl)-methylenesulfonylamides (Ar: C6H5 (1); C6H4–4–CH3 (2); C6H4–4–OC2H5 (3)) on the dynamic strength of the test oil was evaluated by ASTM D2783 (GOST 9490-75) on the four ball friction machine in terms of critical load. The tests were carried out by friction in the corresponding liquids of standardized metal balls made of ShKh 15 steel (microhardness – 64–66 HRC, stiffness parameter – Ra<0.25 μm). The rotation frequency of the upper loaded balls in relation to three stationary balls is 1500 × 1, the oil temperature is 20 °C. The test time at each load is 10 s, the experiment repeatability is three tests for each load.The study of changes in the diameter of the wear spot Dw of metal balls during friction in the initial oil without adding compound (3) and in accordance with the addition was carried out at revolutions of 1500 rpm, an initial temperature of 25 °C, a load of 98 N, and a study time of 1:00. The results obtained indicate that Dw of the oil without making the specified compound was 0.75 mm, and when it was added (0.1 wt. %) – 0.67 mm, that is, the reduction in wear is 10.67 %.It is found that the presence of the studied additives (1)–(3) in low concentrations in a synthetic oil based on pentaerythritol and n-butyric acid can significantly increase its bearing capacity. The most effective compound (3), which at a concentration of 0.1 % of the mass exceeds the bearing capacity in comparison with (4) by 1.38 times, and with (5) – by 1.37 times. The specified compound is more effective in concentration, 10–20 times less in comparison with known additives.Thus, the use of N,N-diallyl (3-arylisoxasol-5-yl)-methylenesulfonylamides as additives to increase the bearing capacity of synthetic oils based on pentaerythritol and synthetic fatty acids, allows to increase the antiwear activity of lubricants. Therefore, they can be used to create new effective compositions for oils and petroleum products.

Synthesys and properties of allyl ethers of phenolphthalein-containing novolacs

The paper presents the results of investigations on the production of allyl ethers of phenolphthalein-containing novolacs, curable without release of low molecular weight substances, and cross-linked copolymers based on them.

Asymmetric Allylic C-H Alkylation of Allyl Ethers with 2-Acylimidazoles.

An asymmetric allylic C-H alkylation of allyl ethers has been established by chiral phosphoramidite-palladium catalysis, affording a wide variety of functionalized chiral 2-acylimidazoles in moderate to high yields and with high levels of enantioselectivity. Moreover, this protocol could be applied to a concise asymmetric synthesis of a tachykinin receptor antagonist.

A fluorescent probe for carbon monoxide based on allyl ether rather than allyl ester: A practical strategy to avoid the interference of esterase in cell imaging

Pd0-mediated Tsuji-Trost reaction is a practical strategy to design fluorescent probes for carbon monoxide (CO) sensing, and in such reaction CO can reduce Pd2+ to Pd0 in-situ and remove allyl groups on fluorophores. In most of these probes, esters are commonly used to link allyl on fluorophores. We found that the ester groups could be hydrolyzed by esterase activity of fetal bovine serum (FBS), while FBS is a requisite in cell culture, and the hydrolysis could interfere the Pd0-mediated Tsuji-Trost reaction. In this study, we synthesized a fluorescent probe (Cou-CO) using allyl ether as reaction site rather than allyl ester. Cou-CO is non-fluorescence, and could react with CO under the presence of Pd0 to form Cou with strong fluorescence, and the maximum excitation and emission wavelengths of Cou are 464 nm and 495 nm respectively. Cou-CO shows excellent selectivity to CO and could avoid the effect of FBS with the limit of detection for CO is 78 nm. Finally, Cou-CO was successfully applied for imaging of CO in living cells.

Cross-Coupling Reaction of Allylic Ethers with Aryl Grignard Reagents Catalyzed by a Nickel Pincer Complex

A cross-coupling reaction of allylic aryl ethers with arylmagnesium reagents was investigated using β-aminoketonato- and β-diketiminato-based pincer-type nickel(II) complexes as catalysts. An β-aminoketonato nickel(II) complex bearing a diphenylphosphino group as a third donor effectively catalyzed the reaction to afford the target cross-coupled products, allylbenzene derivatives, in high yield. The regioselective reaction of a variety of substituted cinnamyl ethers proceeded to give the corresponding linear products. In contrast, α- and γ-alkyl substituted allylic ethers afforded a mixture of the linear and branched products. These results indicated that the coupling reaction proceeded via a π-allyl nickel intermediate.

Difluorophosphonylated Allylic Ether Moiety as a 2'-Modification of RNA-Type Molecules: Synthesis, Thermal, and Metabolic Studies.

The first synthesis of oligonucleotides incorporating URF, a uridine modified with a difluorophosphonylated allylic ether onto the 2'-position, is described. Fluorinated homouridylates and miR-342-3p analogues are efficiently prepared. UV-melting experiments and enzymatic degradation studies indicate this new series of fluorinated oligonucleotides exhibit good and thermal metabolic stability as well as an increased lipophilicity. Comparison with oligonucleotides containing 2'- O-allyluridine instead of URF reveals improvement of these chemical properties is related to the presence of the difluoromethylphosphonate group.

Synthesis of Terpolymers at Mild Temperatures Using Dynamic Sulfur Bonds in Poly(S-Divinylbenzene).

Elemental sulfur (S8) is a byproduct of the petroleum industry with millions of tons produced annually. Such abundant production and limited applications lead to sulfur as a cost-efficient reagent for polymer synthesis. Inverse vulcanization combines elemental sulfur with a variety of monomers to form functional polysulfides without the need for solvents. Short reaction times and straight forward synthetic methods have led to rapid expansion of inverse vulcanization. However, high reaction temperatures (>160 °C) limit the types of monomers that can be used. Here, the dynamic sulfur bonds in poly(S-divinylbenzene) are used to initiate polymerization at much lower temperatures. The S-S bonds in the prepolymer are less stable than S-S bonds in S8, allowing radical formation at 90 °C rather than 159 °C. A variety of allyl and vinyl ethers have been incorporated to form terpolymers. The resulting materials were characterized by 1H NMR, gel permeation chromatography, and differential scanning calorimetry, as well as examining changes in solubility. This method expands on the solvent-free, thiyl radical chemistry utilized by inverse vulcanization to create polysulfides at mild temperatures. This development broadens the range of monomers that can be incorporated thus expanding the accessible material properties and possible applications.

A New Strategy to Synthesize α,ω-Dihydroxy Multiblock Copolymers via [CpRu(CH3 CN)3 ]PF6 /Quinaldic Acid Catalyst.

In this study, a new strategy to synthesize random and alternating multiblock copolymers (MBCs) by the polycondensation of macromonomers' terminal hydroxyl groups with [CpRu(CH3 CN)3 ]PF6 /quinaldic acid as the catalyst is reported, which is often used for the preparation of a variety of biological small molecules via the reaction of allyl ethers. The degrees of hydroxyl functionality (Fn ) of the MBCs are assessed by titration, and the presence of hydroxyl on both the ends of MBCs is also confirmed by a chain-extension experiment of the ring-opening polymerization of D,L-lactide.

Spiro Indane-Based Phosphine-Oxazolines as Highly Efficient P,N Ligands for Enantioselective Pd-Catalyzed Allylic Alkylation of Indoles and Allylic Etherification.

A series of indane-based phosphine-oxazoline ligands with a spirocarbon stereogenic center were examined for palladium-catalyzed asymmetric allylic alkylation of indoles. Under optimized conditions, high yields (up to 98%) and enantioselectivities (up to 98% ee) were obtained with a broad scope of indole derivatives. The ligand was determined to be the most efficient P,N-ligand for this reaction. Moreover, the ligand was also efficient for Pd-catalyzed asymmetric allylic etherification with hard aliphatic alcohols as nucleophiles.

Hydroaminoalkylation/Buchwald-Hartwig amination sequences for the synthesis of benzo-annulated seven-membered nitrogen heterocycles

Reaction sequences consisting of an initial intermolecular titanium-catalyzed hydroaminoalkylation of a suitably ortho-bromophenyl-substituted alkene and a subsequent intramolecular Buchwald-Hartwig amination are used for the synthesis of benzazepine, benzoxazepine, and benzothiazepine derivatives. While in the latter two cases, the hydroaminoalkylation products obtained from an allyl (2-bromophenyl) ether or an allyl (2-bromophenyl) thioether must be purified prior to the subsequent palladium-catalyzed amination step, both reactions can be combined to an efficient one-pot procedure for the synthesis of 2,3,4,5-tetrahydrobenzo[b]azepines when 4-(2-bromophenyl)-1-butene and various N-methylanilines are used as the starting materials.

Gold(I)‐Catalyzed Ring Expansion of Alkynylcyclopropyl Allyl Ethers to Construct Tetrasubstituted Methylenecyclobutanones: A Mechanistic Investigation about the Character of Catalytic Amount of Water

AbstractA gold(I)‐catalyzed ring expansion of alkynylcyclopropyl allyl ethers to produce tetrasubstituted methylenecyclobutanones in moderate to good yields has been disclosed in this paper. This reaction proceeded through an intramolecular [3,3]‐sigmatropic rearrangement followed by [1,2]‐allyl shift pathway in the presence of catalytic amount of water upon gold(I) catalysis. The intriguing reaction mechanism has been proposed on the basis of deuterium and 18O‐labeling experiments, Mass spectroscopic analysis, 1H and 13C nuclear magnetic resonance (NMR) spectroscopic tracking and density functional theory (DFT) calculations. The further transformation of these methylenecyclobutanones into polycyclic skeleton has been realized by a practical three‐step synthetic procedure. Several other transformations have been also indicated.magnified image

Evaluation of mechanical properties and shrinkage stress of thiol-ene-methacrylate dental composites with synthesized fluorinated allyl ether

It has already been reported that incorporation of thiol-ene into methacrylate resin could reduce shrinkage stress significantly. However, the mass fraction of thiol-ene in thiol-ene-methacrylate resin system should be limited because of deterioration of mechanical properties. In order to increase mass fraction of thiol-ene in thiol-ene-methacrylate ternary resin system, a new fluorinated ally ether (FUAE) was synthesized and mixed with pentaerythritol tetra (3-mercaptopropionate) (PETMA) at molar ratio of 1:1 to form new thiol-ene resin system, and then the thiol-ene resin was incorporated into Bis-GMA/TEGDMA resin to prepare thiol-ene-methacrylate resin system. The results of neat resin system showed that incorporation of new thiol-ene resin into methacrylate resin could increase degree conversion of methacrylate functional group and decrease volumetric shrinkage. In order to achieve the similar mechanical properties as methacrylate resin, mass fraction of thiol-ene in ternary resin system should not exceed 30 wt%. Thiol-ene-methacrylate resin systems with 10 wt% to 30 wt% were chosen to prepare dental resin composites, and physiochemical properties such as degree of conversion, volumetric shrinkage, shrinkage stress, flexural properties, and water sorption and solubility of these composites were investigated. The results showed that, compared with methacrylate resin-based dental composite, ternary resin-based dental composites had several advantages, such as higher DC% of methacrylate functional group, lower volumetric shrinkage, lower shrinkage stress, lower water sorption and solubility. The flexural properties of ternary resin-based dental composites were comparable or even better than those of methacrylate resin-based dental composite.