共查询到20条相似文献,搜索用时 15 毫秒
1.
Abstract
New, highly-functionalized dihydrothiophenes are conveniently synthesized from the novel tandem, four-component reactions of 1,3-thiazolidinedione, aldehyde, arylamine, and ethyl cyanoacetate, catalyzed by triethylamine. The reaction mechanism involves the use of Knoevenagel condensation, Michael addition, and ring-opening of 1,3-thiazolidinedione, followed by intramolecular ring closure process. The reaction is diastereoselective and only trans-2,3-dihydrothiophenes were produced in moderate yields. The functionalized dihydrothiophenes can be converted efficiently to the corresponding thiophenes by DCC dehydrogenation reaction. 相似文献2.
Schmidt B Mahmud G Soh S Kim SH Page T O'Halloran TV Grzybowski BA Hoffman BM 《Applied magnetic resonance》2011,40(4):415-425
Abstract
Rapid freeze-quench (RFQ) trapping of short-lived reaction intermediates for spectroscopic study plays an important role in the characterization of biological reactions. Recently, there has been considerable effort to achieve sub-millisecond reaction deadtimes. We present here a new, robust, high-velocity microfluidic mixer that enables such rapid freeze-quenching. It is a based on the mixing method of two impinging jets commonly used in reaction injection molding of plastics. This method achieves efficient mixing by inducing chaotic flow at relatively low Reynolds numbers (Re = 140). We present the first mathematical simulation and microscopic visualization of mixing in such RFQ micromixers, the results of which show that the impinging solutions efficiently mix within the mixing chamber. These tests, along with a practical demonstration in an RFQ setup that involves copper wheels, show that this new mixer can in practice provide reaction deadtimes as low as 100 μs. 相似文献3.
Bita Baghernejad Majid M. Heravi Hossein A. Oskooie Nargess Poormohammad Maliheh Khorshidi Yahia Sh. Beheshtiha 《Molecular diversity》2011,15(1):245-248
Abstract
A simple and efficient synthesis of N-cyclohexyl-benzofuran derivatives was achieved via a one-pot three-component reaction of cyclohexylisocyanide, an aromatic aldehydes, and phenols in DMF for 10 h with good yields. 相似文献4.
Majid M. Heravi Mina Saeedi Yahya S. Beheshtiha Hossein A. Oskooie 《Molecular diversity》2011,15(1):239-243
Abstract
One-pot synthesis of different benzochromeno-pyrazole derivatives has been reported via reaction of aldehydes, 3-methyl-1H-pyrazol-5(4H)-one and α-naphthol/β-naphthol in the presence of sulfamic acid. 相似文献5.
Abstract
Iodine catalyzes the pseudo four-component reaction of an aldehyde, a urea or thiourea, and cyclic 1,3-dicarbonyl compounds under microwave irradiation in a solvent-free condition to yield various σ symmetric spiro heterobicyclic rings in excellent yields. 相似文献6.
Ghasem Marandi Malek T. Maghsoodlou Nourallah Hazeri Sayyed M. Habibi-Khorassani Niloufar Akbarzadeh Torbati Faramarz Rostami-Charati Brian W. Skelton Mohamed Makha 《Molecular diversity》2011,15(1):197-201
Abstract
In a new multicomponent reaction phenanthridine reacts with isocyanides and malonitrile in the presence of benzaldehyde derivatives to produce 2-aryl-3-(alkyl- or arylimino)-2,3-dihydropyrrolo[1,2-f]phenanthridine-1,1(12b H)-dicarbonitrile in a simple, mild, and efficient protocol in excellent yields. 相似文献7.
J. García-Barrasa J. M. López-de-Luzuriaga M. Monge Katerina Soulantica Guillaume Viau 《Journal of nanoparticle research》2011,13(2):791-801
Abstract
Silver nanocrystal superlattices (NCSs) stabilized by hexadecanethiol have been prepared through reduction of [Ag(hexadecanethiolate)] n , formed in situ by reaction of the organometallic precursor [Ag(C6F5)] and hexadecanethiol. The nanostructures have been characterized by transmission electron microscopy (TEM) and X-ray diffractometry (XRD). Several reaction parameters such as solvent (anisole or toluene), reaction temperature (150 or 120 °C) or silver:thiol ratio (1:1 or 2:1) have been studied. The NCSs are formed by silver nanoparticles which sizes range from 3.7 to 5.1 nm, depending on the reaction conditions. The formation a of lamellar phase of di-n-hexadecyldisulfide by oxidation of the hexadecanethiolate ligands bonded to Ag(I) is detected by XRD. 相似文献8.
Angela?M?Jaramillo Xiangzhong?Zheng Yi?Zhou Defne?A?Amado Amanda?Sheldon Amita?Sehgal Irwin?B?Levitan
Background
SLOB binds to and modulates the activity of the Drosophila Slowpoke (dSlo) calcium activated potassium channel. Recent microarray analyses demonstrated circadian cycling of slob mRNA. 相似文献9.
Abstract
Highly substituted novel 4H-pyrimido[1,6-a] pyrimidines were prepared by a trifluoromethanesulfonic acid catalyzed one-pot three-component condensation of 4-aminopyrimidines, aldehydes, and β-ketoesters. A preliminary feasibility study was undertaken on these compounds, to assess the potential production of a library of further diversified compounds by nucleophilic replacement of Cl (R1) or by reaction of electrophiles with the NH2 (R2) group. 相似文献10.
Abstract
The Pictet–Spengler reaction, using polyethylene glycol immobilized tryptophan ester with a variety of ketones, was achieved by refluxing condition in acidic chloroform. The linear as well as cyclic ketones were employed. All the ketones were reacted within 6–8 h to furnish soluble polymer-supported tetrahydro-β-carboline in good yields. Further expansion at N-terminus of tetrahydro-β-carbolines was achieved through a reaction with chloroacetyl chloride. Finally, the 2,5-diketopiperazine skeleton was constructed over a β-carboline by amination of the resulting N-chloroacetamides and subsequent intramolecular cyclization leading to cleavage of the polymer; constitutes a traceless synthesis of tetracyclic molecular architecture. Significantly, this strategy affords a straightforward and efficient approach for the construction of biological promising molecules with high purity and good yields. 相似文献11.
Abstract
A simple, mild, and highly efficient method has been developed for the preparation of functionalized tetrahydropyridines and β-amino carbonyls from the multicomponent reactions involving in situ imines and vanadium (III) chloride as a Lewis acid. The multicomponent reaction of two equivalents of aromatic aldehyde, two equivalents of amine, and one equivalent β-keto ester in the presence of catalytic amount of VCl3 provides highly atom economic five-component tetrahydropyridines in very good yields. The same catalyst was found useful for the efficient synthesis of a wide variety of β-amino ketones using direct-type Mannich reaction of aromatic aldehyde, amine, and aromatic ketones. The notable advantages of this method are simple procedure, short reaction time and good yields, and applicable to broad range of substrates. 相似文献12.
Jerome S Harms Marina A Durward Diogo M Magnani Gary A Splitter 《Journal of immune based therapies and vaccines》2009,7(1):1-14
Background
There is no safe, effective human vaccine against brucellosis. Live attenuated Brucella strains are widely used to vaccinate animals. However these live Brucella vaccines can cause disease and are unsafe for humans. Killed Brucella or subunit vaccines are not effective in eliciting long term protection. In this study, we evaluate an approach using a live, non-pathogenic bacteria (E. coli) genetically engineered to mimic the brucellae pathway of infection and present antigens for an appropriate cytolitic T cell response. 相似文献13.
Abstract
With the emergence of high throughput screening of bioactive molecules, there is constant need for the development of new strategies for diversity-oriented synthesis. We describe here a novel one-pot multicomponent reaction for the synthesis of uracil derivatives using easily available starting materials. This new synthetic strategy provides easy access to diverse uracil derivatives in moderate to good yields. 相似文献14.
Raoul Kopelman 《Journal of statistical physics》1986,42(1-2):185-200
Heterogeneous kinetics are shown to differ drastically from homogeneous kinetics. For the elementary reaction A + A products we show that the diffusion-limited reaction rate is proportional tot
– h[A]2 or to [A]x, whereh=1- d
s/2, X=1+2/d
s
=(h-2)(h-1), andd
s
is the effective spectral dimension. We note that ford = d
s
=1, h =1/2 andX = 3, for percolating clustersd
s = 4/3,h = 1/3 andX = 5/2, while for dust ds <1, 1 >h > 1/2 and >X > 3. Scaling arguments, supercomputer simulations and experiments give a consistent picture. The interplay of energetic and geometric heterogeneity results in fractal-like kinetics and is relevant to excitation fusion experiments in porous membranes, films, and polymeric glasses. However, in isotopic mixed crystals, the geometric fractal nature (percolation clusters) dominates. 相似文献
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16.
Hyun-Jung Choi Ji-Ye Kang In-Yup Jeon Soo-Mi Eo Loon-Seng Tan Jong-Beom Baek 《Journal of nanoparticle research》2012,14(2):704
Abstract
Multi-walled carbon nanotubes (MWCNTs) are functionalized at the sp2 C–H defect sites with 3,4-diaminobenzoic acid by a “direct” Friedel–Crafts acylation reaction in a mild polyphosphoric acid/phosphorous pentoxide medium. Owing to enhanced surface polarity, the resulting 3,4-diaminobenzoyl-functionalized MWCNTs (DAB-MWCNT) are highly dispersible in polar solvents, such as ethanol, N-methyl-2-pyrrolidone, and methanesulfonic acid. The absorption and emission properties of DAB-MWCNT in solution state are qualitatively shown to be sensitive to the pH in the environment. The DAB-MWCNT is used as a stable platform on which to deposit platinum nanoparticles (PNP). The PNP/DAB-MWCNT hybrid displays high electrocatalytic activity with good electrochemical stability for an oxygen reduction reaction under an alkaline condition. 相似文献17.
Ann-Sophie Persson Eric Westman Fu-Hua Wang Firoj Hossain Khan Christian Spenger Catharina Lavebratt 《BMC neuroscience》2007,8(1):10
Background
Mutations in the Shaker-like voltage-gated potassium channel Kv1.1 are known to cause episodic ataxia type 1 and temporal lobe epilepsy. Mice that express a malfunctional, truncated Kv1.1 (BALB/cByJ-Kv1.1 mceph/mceph ) show a markedly enlarged hippocampus and ventral cortex in adulthood. 相似文献18.
Faure K Fujimoto J Shimabukuro DW Ajayi T Shime N Moriyama K Spack EG Wiener-Kronish JP Sawa T 《Journal of immune based therapies and vaccines》2003,1(1):2
Background
The effects of the murine monoclonal anti-PcrV antibody Mab166 on acute lung injury induced by Pseudomonas aeruginosa were analyzed in a rat model. 相似文献19.
Background
ALPK1 (α-kinase 1) is a member of an unconventional alpha-kinase family, and its biological function remains largely unknown. Here we report the phenotypic characterization of one mutant line, in which the piggyBac (PB) transposon is inserted into the Alpk1 gene. 相似文献20.
Wenqi Zeng Tammy Gillis Michael Hakky Luc Djoussé Richard H Myers Marcy E MacDonald James F Gusella 《BMC neuroscience》2006,7(1):62-9