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1.
Xiangfeng Wu Huiran Lu Zhiqiang Wang Xinhua Xu 《Journal of Sol-Gel Science and Technology》2010,54(2):147-153
Heat treated hollow silica beads have been prepared via a two-step method: the fast synthesis of mesoporous hollow silica
beads via soft template method and the closing of the porosity of as prepared hollow silica beads in a vertical furnace at
more than 1,000 °C. The experiment results showed that the size of the as prepared hollow silica beads was greatly affected
by the size of the octylamine vesicles, which increased as the mixing rate decreased, and the optimal synthesis time was 5 min.
Fourier transform-infrared spectroscopy results indicated that the soft template was incorporated in as prepared hollow silica
beads. The optical photographs and the X-ray diffraction results indicated that the shell of as prepared hollow silica beads
was fully densified in the high temperature furnace. In addition, the morphology observation of polypropylene/polyolyaltha
olfin/heat treated hollow silica beads ternary composites indicated that this type of silica beads possessed high intensity
and strength to blend with the polypropylene/polyolyaltha olfin composites. 相似文献
2.
Synthesis and pharmacology of glutamate receptor ligands: new isothiazole analogues of ibotenic acid
Jørgensen CG Clausen RP Hansen KB Bräuner-Osborne H Nielsen B Metzler B Metzler BB Kehler J Krogsgaard-Larsen P Madsen U 《Organic & biomolecular chemistry》2007,5(3):463-471
The naturally occurring heterocyclic amino acid ibotenic acid (Ibo) and the synthetic analogue thioibotenic acid (Thio-Ibo) possess interesting but dissimilar pharmacological activity at ionotropic and metabotropic glutamate receptors (iGluRs and mGluRs). Therefore, a series of Thio-Ibo analogues was synthesized. The synthesis included introduction of substituents by Suzuki and Grignard reactions on 4-halogenated 3-benzyloxyisothiazolols, reduction of the obtained alcohols, followed by introduction of the amino acid moiety by use of 2-(N-tert-butoxycarbonylimino)malonic acid diethyl ester. The obtained Thio-Ibo analogues (1, 2a-g) were characterized in functional assays on recombinant mGluRs and in receptor binding assays on native iGluRs. At mGluRs, the activity at Group II was retained for compounds with small substituents (2a-2d), whereas the Group I and Group III receptor activities for all new compounds were lost. Detection of NMDA receptor affinity prompted further characterization, and two-electrode voltage-clamp recordings at recombinant NMDA receptor subtypes NR1/NR2A-D expressed in Xenopus oocytes were carried out for compounds with small substituents (chloro, bromo, methyl or ethyl, compounds 2a-d). This series of Thio-Ibo analogues defines a structural threshold for NMDA receptor activation and reveals that the individual subtypes have different steric requirements for receptor activation. The compounds 2a and 2c are the first examples of agonists discriminating individual NMDA subtypes. 相似文献
3.
A versatile, efficient method for the preparation of alpha-monofluoromethylene (-CHF-) phosphonates from alpha-fluorovinylphosphonate provides access to a class of lysophosphatidic acid (LPA) receptor-subtype agonists. In addition, sn-2 O-methylation of alpha-monofluoromethylene phosphonates using trimethylsilyldiazomethane generated sn-1-acyl, 2-O-methyl alpha-monofluoromethylene derivatives. Finally, a novel method for the selective etherification of 1,2-diols was developed and a new class of sn-1 O-methyl, 2-acyl alpha-monofluoromethylene LPA analogues was prepared. [reaction: see text] 相似文献
4.
Hematite template route to hollow-type silica spheres 总被引:1,自引:0,他引:1
Hollow-type silica spheres with controlled cavity size were prepared from Fe2O3-SiO2 core-shell composite particles by selective leaching of the iron oxide core materials using acidic solution. The spherical Fe2O3 core particles with a diameter range of 20-400 nm were first prepared by the hydrolysis reaction of iron salts. Next, the Fe2O3-SiO2 core-shell particles were prepared by the deposition of a SiO2 layer onto the surface of Fe2O3 particles using a two-step coating process, consisting of a primary coating with sodium silicate solution and a subsequent coating by controlled hydrolysis of tetraethoxysilicate (TEOS). The Fe2O3 core was then removed by dissolving with acidic solution, giving rise to hollow-type silica particles. Scanning electron microscopy clearly revealed that the cavity size was closely related to the initial size of the core Fe2O3 particle. According to the cross-sectional view obtained by transmission electron microscopy, the silica shell thickness was about 10 nm. The porous texture of the hollow-type silica particles was further characterized by nitrogen adsorption-desorption isotherm measurements. 相似文献
5.
[reaction: see text] The utility of functionalized 1,4-diamines, produced via a temporary phosphorus tether (P-tether)/ring-closing metathesis (RCM)/hydrolysis sequence, is demonstrated in the synthesis of structurally diverse DMP 323 analogues. These 1,4-diamines are transformed into various seven-membered heterocycles via insertion of the appropriate nuclei "X". Subsequent derivatization generates heterocyclic diols that are similar in structure to DMP 323, a notable member of a class of highly potent inhibitors of HIV protease. 相似文献
6.
Angeli M Bandini M Garelli A Piccinelli F Tommasi S Umani-Ronchi A 《Organic & biomolecular chemistry》2006,4(17):3291-3296
A practical catalytic approach to the synthesis of 4-substituted 1,2,3,4-tetrahydro-beta-carbolines (THBCs, 1) and 1,2,3,9-tetrahydropyrano[3,4-b]indoles (2) via InBr3-catalyzed intramolecular Friedel-Crafts (F-C) cyclization is described. The use of cross-metathesis reaction represents a direct route to the cyclization precursors and the use of InBr3 (5 mol%) allowed polycyclic indole compounds to be isolated in high yields under mild reaction conditions (rt, DCM, minutes). Finally, efforts toward the development of a stereocontrolled version of the present cyclization are presented, highlighting [salenAlCl] and bimetallic [(salenAlCl)2-InBr3] system as promising chiral Lewis acids (ee up to 60%). 相似文献
7.
Krystyna Jackowska Aleksander T. Bieguński Magdalena Tagowska 《Journal of Solid State Electrochemistry》2008,12(4):437-443
The article reviews the application of a hard template approach in the formation of conducting polymers nanostructures. The
method involves the synthesis of a polymer within the pores or channels of a template. The influence of synthesis conditions
on fundamental features of nanostructured polypyrrole, polyaniline, and their derivatives is discussed.
Dedicated to the 70th birthday of Professor Oleg Petrii. 相似文献
8.
[reaction--see text] (-)-Shikimic acid, the key intermediate in the shikimate pathway in plants and microorganisms, has been synthesized in an enantioconvergent manner from both enantiomeric starting materials by employing a palladium-mediated elimination reaction as the key step. 相似文献
9.
10.
A series of coumarins was synthesised via the silica tungstic acid-catalysed Pechmann reaction; some of these were employed for known three-component reactions with aromatic aldehydes and malononitrile in the presence of sodium hydrogen phosphate (Na2HPO4) as a basic catalyst, affording a variety of potentially anti-HIV active khellactone analogues. 相似文献
11.
Andrew J. G. Baxter Pamela Davis Roger J. Ponsford Robert Southgate 《Tetrahedron letters》1980,21(52):5071-5074
3-(2-Pyrimidinylthio-) substituted olivanic acid analogues, with and without a C-6 hydroxyethyl substituent, have been synthesised in high yield using an intramolecular Wittig reaction followed by deprotection to afford zwitterions with high antibacterial activity. 相似文献
12.
《Tetrahedron letters》1987,28(39):4589-4590
A highly stereoselective synthesis of the side chain of 25-hydroxyvitamin D2 and 1α,25-dihydroxyvitamin D2 is described. 相似文献
13.
The lithium enolate of (2S,3S,5S,6S)-dimethoxy-2,3-dimethyl-1,4-dioxane-5,6-dithiocarboxylate undergoes stereoselective mono- and/or dialkylations to afford two new stereogenic centers. The alkylation products obtained possessed a cis stereochemistry, which was confirmed by the synthesis of natural 4'-O-methylpiscidic acid dimethyl ester . 相似文献
14.
Krishnakumar KS Goudedranche S Bouchu D Strazewski P 《The Journal of organic chemistry》2011,76(7):2253-2256
We are reporting on the utility of commercial vinyl isocyanate for a practical synthetic route from adenosine to N(6)-bis-demethylpuromycin in seven steps and 65% overall yield. A clean one-pot conversion of 3'-bromo-2'-carbamoyl derivative 8 to 3'-amino-3'-deoxyadenosine derivative 10 is the main feature of this synthetic pathway. This synthesis is the shortest synthetic route toward 3'-(aminoacylamido)deoxyadenosines to date. 相似文献
15.
[structure: see text]. Several novel scyphostatin analogues have been prepared in up to 18% yield over five steps from commercially available 4-bromoguaiacol, utilizing an organometallic addition to afford the desired syn-hydroxy-epoxides. 相似文献
16.
ZnS and ZnSe precursors (ZnS x 0.5en and ZnSe x 0.5en, en = ethylenediamine) were prepared via a solvothermal process using ethylenediamine as solvent. Phase-pure hexagonal wurtzite ZnS and ZnSe products were obtained by annealing the precursors in argon stream at temperatures above 350 degrees C. The role of ethylenediamine as a structure-directing coordination molecular template responsible for the morphologies of the annealed products was discussed. This work provided further insights into the solvent coordination molecular template (SCMT) mechanism previously proposed to explain the growth mechanism of CdE (E = S, Se, Te) nanorods in ethylenediamine (Inorg. Chem. 1999, 38, 1382). The as-prepared precursors as well as the annealed products were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), infrared absorbance spectroscopy (IR), thermogravimetric analysis (TGA), X-ray fluorescence (XRF) analysis, and combustion analysis for C, N, H contents. 相似文献
17.
Leseurre L d'Herouville Fle B Püntener K Scalone M Genêt JP Michelet V 《Organic letters》2011,13(12):3250-3253
A highly efficient Pd-catalyzed P-C coupling reaction of easily accessible atropisomeric bisphosphane is described in the presence of various electron-poor aromatic iodides. The reactions are conducted in the presence of a Pd(II)/dppf catalyst in acetonitrile at 80 °C. The reaction conditions are compatible with several electron-withdrawing groups such as esters, cyano, chloro, and trifluoromethyl groups and lead to atropisomeric MeOBIPHEP derivatives in good to excellent yields and high enantiomeric purities. 相似文献
18.
Yoshida T Nishiyachi M Nakashima N Murase M Kotani E 《Chemical & pharmaceutical bulletin》2002,50(6):872-876
The Stille coupling reaction of stannylindole 12 with 4-iodoimidazole 13 (or 24) in the presence of PdCl(2)(PPh(3))(2) gave the corresponding indole-imidazole coupling product 14 (or 25), thereby affording a new synthetic approach to the alkaloid granulatimide (7), isolated from the Brazilian ascidian Didemnum granulatum, as well as its structural analogues, 10-methylgranulatimide (23), 17-methylgranulatimide (30), 10,17-dimethylgranulatimide (31). 相似文献
19.
New route to ABCD-porphyrins via bilanes 总被引:1,自引:0,他引:1
Dogutan DK Zaidi SH Thamyongkit P Lindsey JS 《The Journal of organic chemistry》2007,72(20):7701-7714
A new strategy for preparing porphyrins that bear up to four different meso-substituents (ABCD-porphyrins) relies on two key reactions. One key reaction entails a directed synthesis of a 1-protected 19-acylbilane by acid-catalyzed condensation at high concentration (0.5 M) of a 1-acyldipyrromethane and a 9-protected dipyrromethane-1-carbinol (derived from a 9-protected 1-acyldipyrromethane). Three protecting groups (X) were examined, including thiocyanato, ethylthio, and bromo, of which bromo proved most effective. The bilanes were obtained in 72-80% yield, fully characterized, and examined by 15N NMR spectroscopy. The second key reaction entails a one-flask transformation of the 1-protected 19-acylbilane under basic, metal-templating conditions to give the corresponding metalloporphyrin. The reaction parameters investigated for cyclization of the bilane include solvent, metal salt, base, concentration, temperature, atmosphere, and time. The best conditions entailed the 1-bromo-19-acylbilane at 100 mM in toluene containing DBU (10 mol equiv) and MgBr2 (3 mol equiv) at 115 degrees C exposed to air for 2 h, which afforded the magnesium porphyrin in 65% yield. The magnesium porphyrin is readily demetalated to give the free base porphyrin. A stepwise procedure (which entailed treatment of the 1-(ethylthio)-19-acylbilane to oxidation, metal complexation, desulfurization, carbonyl reduction, and acid-catalyzed condensation) was developed but was much less efficient than the one-flask process. The new route to ABCD-porphyrins retains the desirable features of the existing "2 + 2" (dipyrromethane + dipyrromethane-1,9-dicarbinol) method, such as absence of scrambling, yet has significant advantages. The advantages include the absence of acid in the porphyrin-forming step, the use of a metal template for cyclization, the ability to carry out the reaction at high concentration, the lack of a quinone oxidant, avoidance of use of dichloromethane, and the increased yield of macrocycle formation to give the target ABCD-metalloporphyrin. 相似文献
20.
[reaction: see text] Convenient conditions are described for the transformation of alpha-aminonitriles to the tetrazole analogues of alpha-amino acids. Refluxing the starting material in water/2-propanol at 80 degrees C with sodium azide and catalytic zinc bromide affords the tetrazole product in yields generally exceeding 90%. 相似文献