Synthesis of macrocyclic-acyclic polyether-ester compounds with isoxazole units

A series of macrocyclic-acyclic ether-ester compounds containing the isoxazole ring has been prepared by treating various dihydroxy compounds with 3,5-isoxazoledicarbonyl chloride.     

Synthesis of chiral diaza-crown ethers incorporating carbohydrate units

A synthesis of a novel chiral diaza crown ethers derived from α-D-glucose, α-D-mannose, and α-D-galactose in two alternative pathways is described.     

Synthesis and photochromic reactivity of macromolecules incorporating four dithienylethene units

Two macrocycles bearing four dithienylethene units were synthesized. Upon irradiation of the macrocycles 5 and 6 with ultraviolet light, only one or two photo-induced cyclization reaction occurs. Each isomers were isolated and analyzed by ¹H NMR spectrum. The quantum yield of 5 and 6 are 0.58 and 0.64, respectively. The high value is due to the presence of enforced antiparallel conformation in the macrocycles 5 and 6.     

Synthesis of new isoxazole aminoalcohols

The preparation of new 1-isoxazolyl-2-amino-1-ethanol derivatives is described starting from the corresponding 1-isoxazolylethanones. It is also reported the synthesis of 1-(5-isoxazolyloxy)-3-amino-2-propanol compounds starting from the corresponding 5-haloisoxazoles and the obtainment of 1-(3-isoxazolyloxy)-3-amino-2-propanol compounds starting from the methyl 3-hydroxy-5-isoxazolecarboxylate.     

Synthesis and characterization of polyaryleneetherketone triphenylphosphine oxides incorporating cycloaliphatic/cage hydrocarbon structural units

New high temperature polyaryleneetherketone triphenylphosphine oxides incorporating trans‐1,4‐cyclohexane, 1,3‐adamantane, and 4,9‐diamantane structural units were synthesized by the base‐promoted polymerization reaction between 4,4′‐difluorotriphenylphosphine oxide and the novel dihydroxy monomers trans‐1,4‐bis(4‐hydroxybenzoyl)cyclohexane, 1,3‐bis(4‐hydroxybenzoyl)adamantane, and 4,9‐bis(4‐hydroxybenzoyl)diamantane. The monomers were synthesized in a good yield by a two‐step procedure involving the Friedel–Crafts acylation of anisole by the diacid chlorides trans‐1,4‐cyclohexanedicarbonyl chloride, 1,3‐adamantanedicarbonyl chloride, and 4,9‐diamantanedicarbonyl chloride, followed by demethylation with pyridine hydrochloride. The polymers, which could be processed into tough, free standing films from organic solvents, exhibited high T_g's in the range of 192–239° as well as thermooxidative stabilities (5% weight loss in air) in the range of 445–490°. Preliminary results from a UV–visible spectroscopic study of dilute solutions of the polymers in chloroform showed absorption maxima in the 263–274 nm region and transparency to spectral radiation in the 300–800 nm range, indicating that these triphenylphosphine oxide polymers could have potential applications for space thermal control coatings. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6134–6142, 2004     

Decomposition of a-type sandwiches. Synthesis and characterization of new polyoxometalates incorporating multiple d-electron-centered units

The controlled decomposition of the sandwich-type polyoxometalates K(12)[(M(OH(2))(2))(3)(A-alpha-PW(9)O(34))(2)] (where M = Mn(II) or Co(II)) in 0.5 M NaCl yields a new family of transition metal substituted POMs of the general formula [((MOH(2))M(2)PW(9)O(34))(2)(PW(6)O(26))](17)(-) (where M = Mn(II) (1Mn) or Co(II) (1Co)). The structure of 1Mn, determined by single-crystal X-ray diffraction (a = 17.4682(10) A, b = 22.3071(12) A, c = 35.1195(18) A, beta = 95.898(1) degrees, monoclinic, P2(1)/c, Z = 4, R(1) = 6.19%, based on 50264 independent reflections), consists of two B-alpha-(Mn(II)OH(2))Mn(II)(2)PW(9)O(34)(3)(-) units joined by a B-type hexavacant PW(6)O(26)(11)(-) fragment to form a C-shaped polyoxometalate. A low resolution X-ray structure of the Co(II) analogue, 1Co, was also obtained. The UV-visible spectrum of 1Co shows the characteristic charge-transfer bands of polyoxometalates as well as a new Co-centered peak (560 nm, epsilon = 416 M(-)(1) cm(-)(1)) which appears at a higher wavelength relative to that exhibited by the parent A-type sandwich, K(12)[(Co(OH(2))(2))(3)(A-alpha-PW(9)O(34))(2)]. The methyltricaprylammonium salt of 1Mn is an effective catalyst for the H(2)O(2)-based epoxidation of cis-cyclooctene, cyclohexene, and 1-hexene.     

Synthesis of functionally substituted isoxazole and isothiazole derivatives

Acylation of benzene and toluene with 5-phenyl- and 5-(p-tolyl)isoxazole-3-carbonyl chlorides gave 5-phenyl(or p-tolyl)isoxazol-3-yl phenyl(or p-tolyl)ketones which were reduced to the corresponding alcohols with sodium tetrahydridoborate in propan-2-ol. Selective reduction of the carboxy group in 4,5-dichloroisothiazole-3-carboxylic acid was achieved by the action of BH₃, and the aldehyde group in 4-formyl-2-methoxyphenyl 5-arylisoxazole-3-carboxylates and 4,5-dichloroisothiazole-3-carboxylates was reduced to hydroxymethyl group with sodium triacetoxyhydridoborate in benzene. Acylation of the resulting hydroxymethyl derivatives with 5-arylisoxazole- and 4,5-dichloroisothiazole-3-carbonyl chlorides afforded the corresponding esters containing two azole fragments in their molecules.     

Synthesis and properties study of novel ferrocenyl isoxazole derivatives

A synthetic procedure based on the 1,3‐dipolar cycloaddition reactions of nitrile oxides and ethynylferrocene derived from ferrocene has been developed to synthesize new ferrocenyl‐isoxazole derivatives. The stable solids were thoroughly characterized by ¹H NMR, FT‐IR, and mass spectroscopy. The structure of (η⁵‐C₅H₅) Fe (η⁵‐C₅H₄) C₃HNOC₆H₄CH₃ was determined by single‐crystal X‐ray diffraction. The electrochemical behaviors of the synthesized ferrocenyl‐isoxazole derivatives were also studied. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis and structure of [2.2]paracyclophanes incorporating alkyne units in the extended linear chain

The novel [2.2]paracyclophanes 4-7 with an extended π-conjugation due to the presence of a linear arylethynyl chain have been synthesized by the Pd-catalyzed Sonogashira coupling reaction.     

Synthesis of hydroxybenzaldehyde derivatives containing an isoxazole heteroring

5-Phenyl(p-tolyl)isoxazole-3-carboxylic acids were synthesized starting from 3-hydroxyiminomethyl-5-phenyl(p-tolyl)isoxazoles, and their reactions with p-hydroxybenzaldehyde, vanillin, isovanillin, o-vanillin, and ethyl vanillin gave the corresponding esters. The latter were brought into condensation with aromatic amines to obtain Schiff bases which were reduced to amines.     

Oligothienylenevinylenes incorporating 3,4-ethylenedioxythiophene (EDOT) units

A new series of π-conjugated oligomers based on various combinations of thiophene and EDOT units and double bonds has been synthesized by Wittig-Horner reactions from phosphonate anions carrying EDOT or bis-EDOT units. Optical and electrochemical results evidence the crucial role of the EDOT moiety for modulating the electronic properties of the oligomers. The insertion of bis-EDOT unit in the middle of the molecule leads to a self-rigidification of the conjugated system due to non covalent S?O intramolecular interactions. The strong electron donor effect of the EDOT units explains the determining role of the relative position of the EDOT units on the localization and stabilization of the positive charges in the radical cation or dication states.     

Synthesis and Characterisation of the Sodium and Lithium Cryptates of Macrobicyclic Ligands incorporating pyridine,bipyridine, and biisoquinoline units

Sythetic procedures have been deweloped for the preparation of sodium and lithium cryptates of the macrabicyclic ligands 1–11 containing pyridine, bipyridine, and biisoquinoline groups. They involve stepwise construction of the bicyclic system as will as direct macrobicyclisation procedures (Scheme 1) and give access to both symmetrical and dissymmetrical structures. Marked cation template effects have been found that facilitate the cyclisation processes. The ligands 1–11 were isolated as their cryptates with Na⁺ or Li⁺ cations.     

Synthesis,regioisomerism and characterization of unsymmetrical alkenyl-terminated isoxazole liquid crystals

Two series of unsymmetrical diphenyl-1,3-diketones, each species bearing one terminal alkene, have been synthesized. These diketones have been converted into their respective unsymmetrical diphenylisoxazoles [3(5)-(4-ω-alkenyloxyphenyl)-5(3)-(4-alkoxyphenyl)isoxazoles] which have been isolated as equal mixtures of two regioisomers, due to 3,5- and 5,3-substitution of the isoxazole ring. The mesogenic properties of the isoxazole liquid crystals have been studied by polarizing optical microscopy and DSC. The effect of increasing alkoxy chain length (C6-C10) on the properties of the two series of isoxazoles has been examined. The isoxazoles show enantiotropic smectic C, smectic A and nematic mesophases. A detailed ¹H and ¹³C NMR spectroscopic study has examined both the 1,3-diketones and isoxazoles. Proximity of the terminal alkene to the diphenyl core can greatly affect the complexity of the ¹³C NMR spectra.     

Synthesis of some sulfonium salts and ylides containing the isoxazole nucleus

Some dimethylisoxazolylmethylsulfonium salts and the corresponding ylides were synthetized and their chemical behaviour studied. Dimethylsullonium-5-isoxazolyl methylides (XIa,b) give 5-isoxazolyloxiranes (XIIa,d) and XIII when allowed to react with carbonyl compounds. Ring opening products from these oxiranes are also reported.     

Synthesis, regioisomerism and characterization of unsymmetrical alkenyl-terminated isoxazole liquid crystals

Two series of unsymmetrical diphenyl-1,3-diketones, each species bearing one terminal alkene, have been synthesized. These diketones have been converted into their respective unsymmetrical diphenylisoxazoles [3(5)-(4-ω-alkenyloxyphenyl)-5(3)-(4-alkoxyphenyl)isoxazoles] which have been isolated as equal mixtures of two regioisomers, due to 3,5- and 5,3-substitution of the isoxazole ring. The mesogenic properties of the isoxazole liquid crystals have been studied by polarizing optical microscopy and DSC. The effect of increasing alkoxy chain length (C6-C10) on the properties of the two series of isoxazoles has been examined. The isoxazoles show enantiotropic smectic C, smectic A and nematic mesophases. A detailed ¹H and ¹³C NMR spectroscopic study has examined both the 1,3-diketones and isoxazoles. Proximity of the terminal alkene to the diphenyl core can greatly affect the complexity of the ¹³C NMR spectra.     

Phosphorous(III) compounds incorporating perfluoroalkyl-derivatised biphenolic units

A perfluoroalkyl-derivatised biphenol has been prepared. Using this unit, the synthesis of a series of perfluoroalkyl-derivatised phosphorus(III) ligands incorporating chelation at the phosphorus centre is described.