Addition of Nitrile Oxides to Aryl Allyl Ethers

3,5-Disubstituted isoxazolines with an aryloxymethyl group in position 5 have been synthesized. The [2+3] cycloaddition reaction of benzonitrile oxide to a 5-chlorosalicylic acid derivative containing two allyl groups occurs to give a compound with an oxazolinylmethyl fragment both in the ester and the ether parts of the molecule. The addition of nitrile oxides to the aryl allyl ethers occurs regiospecifically to give the 5-substituted isomer.     

Living cationic polymerization of isobutyl vinyl ether using a variety of metal oxides as heterogeneous catalysts: Robust,reusable, and environmentally benign initiating systems

Cationic polymerization of isobutyl vinyl ether (IBVE) was examined using a variety of metal oxides in conjunction with IBVE–HCl adduct as a cationogen in toluene at 0 °C. Iron oxides (α‐Fe₂O₃, γ‐Fe₂O₃, and Fe₃O₄) induced living polymerization in the presence of an added base, ethyl acetate or 1,4‐dioxane, to give polymers with very narrow molecular weight distributions (MWDs). Conversely, with other metal oxides such as Ga₂O₃, In₂O₃, ZnO, Co₃O₄, and Bi₂O₃, polymers with bimodal MWDs, including long‐lived species along with uncontrolled higher molecular weight portions, were produced in the presence of an added base. A small amount of nBu₄NCl or 2,6‐di‐tert‐butylpyridine (DTBP) suppressed the uncontrolled portion to induce controlled reactions with Ga₂O₃, In₂O₃, and ZnO. The roles of these reagents are discussed in terms of the nature of the active sites of the catalyst surface and the polymerization mechanisms. In addition, the reusability of the catalyst, the effect of stirring before and during polymerization, and the estimation of the number of active sites are also described. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 916–926, 2010     

Twenty-five Years of "Crowning" Around: Synthesis of Crown Ethers at Brigham Young University

A review of the synthesis of crown ethers at Brigham Young University ispresented. Topics include: thiacrown ethers, diestercrown ethers,proton-ionizable crown ethers, chiral crown ethers, azacrown ethers,cryptands and other polycyclic ligands, and the Mannich reaction method toprepare azacrown ethers and cryptands.     

Novel monoaza- and diazacrown ethers incorporating sugar units and their extraction ability towards picrate salts

A number of new 15- and 1 8-membered ring aza-crown (4, 5, 8–13, 17, 18) and lariat ethers (6, 7) incorporating glucose or galactose units have been synthesized in good yields by a simple route. Their extracting abilities were measured with Li⁺, Na⁺, K⁺ and NH ₄ ⁺ cations. The substituents at the nitrogen atom and the type of monosaccharide affected this property significantly.     

大环多元醚在分析化学中的应用

综述了大环多元醚的分析特性及在分析化学中的应用，并对其发展趋势作出展望。     

Relative thermodynamic stabilities of allyl vinyl and propenyl vinyl ethers

The relative thermodynamic stabilities of a number of isomeric allyl vinyl and propenyl vinyl ethers were determined by chemical equilibration in DMSO solution with KOBu-t as catalyst. From the temperature dependence of the values of the equilibrium constant the parameters G _m , H _m and S _m of isomerization at 298.15 K were evaluated. Propenyl vinyl ethers, owing to their low enthalpy contents, are much more stable than the isomeric allyl vinyl ethers. It appears that in the parent propenyl vinyl ether, the Me group attached to C- of the divinyl ether skeleton has a strong stabilizing effect, comparable to that of alkyl groups in ordinary olefins, on the unsaturated system. In more heavily alkyl-substituted divinyl ethers, however, the stabilizing effects of alkyl groups are less prominent, being comparable to the low stabilization energies of alkyl groups in vinyl ethers, and depend moreover, on the pattern of substitution.     

Synthesis and characterization of a biphenyl perfluorocyclobutyl (BP‐PFCB) polyethylene glycol (PEG) blend compatibilizer

Polyethylene glycol (PEG) end‐capped trifluorovinyl ether (TFVE) telechelomer was synthesized in one step via esterification of 4‐(trifluorovinyloxy) benzoic acid. The new telechelomer was characterized by attenuated total reflectance Fourier transform infrared (ATR‐FTIR), elemental analysis, and by ¹⁹F and ¹H nuclear magnetic resonance (NMR) spectroscopy. The telechelomer and 4,4′‐bis(4‐trifluorovinyloxy)biphenyl (BPVE) were thermally copolymerized via step‐growth [2 + 2] cycloaddition at 160°C. The polymerization afforded PEG enchained biphenyl perfluorocyclobutyl (BP‐PFCB) copolymers that are solution processable and film forming. These copolymers were characterized by ATR‐FTIR, ¹⁹F NMR, and ¹H NMR. Gel permeation chromatography (GPC) gave number‐average molecular weight (M_n) ranging 11,000 to 12,000. Compatibilization of PEG and a commercial polymer BP‐PFCB was achieved utilizing the new PEG BP‐PFCB copolymer, 3‐co2‐4 . It was found that 5 wt% of 3 ‐ co2 ‐ 4 was ideal to reduce interfacial tension by scanning electron microscope (SEM). In addition, phase homogeneity was studied by differential scanning calorimetry (DSC). Copyright © 2016 John Wiley & Sons, Ltd.     

The Chemistry of Enol Ethers

Enol ethers (vinyl ethers) are intermediate in their reaction behavior between olefins and enamines. This article presents a survey of reactions leading to bond formation at the β? C atom of enol ethers; polymerizations and additions of acidic H? X compounds are not reviewed.     

New methodology for the synthesis of benzoazacrown ethers by transformation of the macrocycle of benzocrown ethers

The review summarizes the results of studies aimed at constructing new promising macrocyclic ligands that bind metal and ammonium ions. A new approach to the synthesis of formyl and nitro derivatives of 1-aza-2,3-benzocrown ethers possessing considerable synthetic potential is described. The review presents a radically new methodology for the synthesis of such benzoazacrown ethers based on stepwise transformations of the macrocycle of readily accessible benzocrown ethers. The main structural factors and necessary conditions enabling stepwise transformations of the macrocycle of crown ethers into azacrown ethers were revealed. For the first time, the ability of N-methylbenzoazacrown ethers to form complexes was found, which is much superior to that of widely used N-phenylazacrown ethers and benzocrown ethers with the same size of the macrocycle.     

Efficient oxidative deprotection of trimethylsilyl, tetrahydropyranyl and methoxymethyl ethers under solvent-free conditions

A mild, efficient and fast method for direct oxidation of trimethylsilyl, tetrahydropyranyl and methoxymethyl ethers to their corresponding carbonyl compounds using trinitratocerium（Ⅳ） bromate （TNCB） supported on NaHSO4.H2O under solvent-free conditions is reported.     

Cerium(IV) sulfate tetrahydrate: a catalytic and highly chemoselective deprotection of THP,MOM, and BOM ethers

Tetrahydropyranyl (THP), methoxymethyl (MOM), and benzyloxymethyl (BOM) phenyl/alkyl ethers were efficiently cleaved to the corresponding parent hydroxyl compounds in good yields using catalytic amounts of Ce(SO₄)₂·4H₂O by microwave-assisted or conventional heating in methanol solution. Intramolecular and competitive experiments demonstrated the chemoselective deprotection of THP ethers in the presence of triisopropylsilyl (TIPS) and tert-butyldiphenylsilyl (TBDPS) phenyl ethers.     

Tetraphenylporphyrins monosubstituted with a crown ether in one phenyl ring. Synthesis and characterization

Summary The synthesis and spectroscopic characterization of seven new tetraphenyl-porphyrins (1–7) derivatized with 12-crown-4, 14-crown-4, 15-crown-5, or 18-crown-6 ether units inortho orpara position of one of the phenyl rings is described.

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In einem Phenylring mit Kronenethern monosubstituierte Tetraphenylporphyrine. Synthese und Charakterisierung

Zusammenfassung Die Synthese und die spektroskopische Charakterisierung sieben neuer Tetraphenylporphyrine (1–7), die mit 12-Krone-4, 14-Krone-4, 15-Krone-5 oder 18-Krone-6 in derortho-oderpara-Position eines Phenylrings substituiert sind, werden beschrieben.

     

Dilithiated synthons: synthesis of cyclic ethers

Recent advances in the generation of dilithiated synthons by arene-catalyzed lithiation of the corresponding dichloro compounds in the presence of carbonyl compounds (Barbier-type reaction conditions) as the key step are described. Further cyclization of the generated diols under different reaction conditions affords a variety of mono-, bi-, and spirocyclic ethers.     

Synthesis of Functionalized Allylsilanes Using 3-(Stannyl)-2-(silylmethyl)propene

Reactions of 3-tributylstannyl-2-(trimethylsilymethyl)propene with acid chlorides or aldehydes proceed smoothly without any catalytic activation to afford allylsilanes bearing various functionalities.     

Facile one-pot synthesis of aliphatic bridged diaryloxy compounds,cyclic and crown ethers under mild conditions

We report here the facile, room temperature, catalyst free, one pot synthesis of aliphatic bridged diaryloxy compounds, cyclic and crown ethers. Anhydrous potassium carbonate (K₂CO₃) as a mild base along with dimethyl sulfoxide generates the phenoxide ion which facilitates the nucleophilic substitution of bromoalkanes to yield the corresponding crown ethers.     

Synthesis of diaryl ethers based on one-pot [3+3] cyclizations of 1,3-bis(silyl enol ethers)

Functionalized and sterically encumbered diaryl ethers were prepared by [3+3] cyclization of 1,3-bis(silyl enol ethers) with 2-aryloxy-3-(silyloxy)alk-2-en-1-ones.