Oxime derivatives as α-electrophiles. from α-tetralone oximes to tetracyclic frameworks

When subjected to the conditions of a Semmler-Wolff/Schroeter aromatization, the oximes of 4-benzyl-substituted tetralones undergo an electrophilic aromatic substitution reaction to form tetracyclic frameworks.     

A novel four-component reaction for the synthesis of disubstituted 1,3,4-oxadiazole derivatives

The 1:1 imine intermediate generated by the addition of benzyl amine to cyclobutanone is trapped by (N-isocyanimino)triphenylphosphorane in the presence of an aromatic carboxylic acid leads to the formation of the corresponding iminophosphorane intermediate. Disubstituted 1,3,4-oxadiazole derivatives are formed via intramolecular aza-Wittig reaction of the iminophosphorane intermediate. The reactions were completed in neutral conditions at room temperature. The disubstituted 1,3,4-oxadiazole derivatives, were produced in excellent yields.     

Development of a Method for the Determination of Polychlorinated Biphenyls in Microplastics Present in Marine Samples

Journal of Analytical Chemistry - In this work, a method for the determination of nine polychlorinated biphenyls (PCBs) in three polymer types (polyethylene terephthalate, PET; unplasticized...     

Conjugate Phase Change Heat Transfer in an Inclined Compound Cavity Partially Filled with a Porous Medium: A Deformed Mesh Approach

In this paper, the melting process of a PCM inside an inclined compound enclosure partially filled with a porous medium is theoretically addressed using a novel deformed mesh method. The sub-domain area of the compound enclosure is made of a porous layer and clear region. The right wall of the enclosure is adjacent to the clear region and is subject to a constant temperature of T_c. The left wall, which is connected to the porous layer, is thick and thermally conductive. The thick wall is partially subject to the hot temperature of T_h. The remaining borders of the enclosure are well insulated. The governing equations for flow and heat transfer, including the phase change effects and conjugate heat transfer at the thick wall, are introduced and transformed into a non-dimensional form. A deformed grid method is utilized to track the phase change front in the solid and liquid regions. The melting front movement is controlled by the Stefan condition. The finite element method, along with Arbitrary Eulerian–Lagrangian (ALE) moving grid technique, is employed to solve the non-dimensional governing equations. The modeling approach and the accuracy of the utilized numerical approach are verified by comparison of the results with several experimental and numerical studies, available in the literature. The effect of conjugate wall thickness, inclination angle, and the porous layer thickness on the phase change heat transfer of PCM is investigated. The outcomes show that the rates of melting and heat transfer are enhanced as the thickness of the porous layer increases. The melting rate is the highest when the inclination angle of the enclosure is 45°. An increase in the wall thickness improves the melting rate.

     

Detection reagents used for on-plate identification of organic pesticides in biological samples with preliminary separation by TLC/HPTLC

Many specific and non-specific chromogenic spray reagents have been used to detect organic pesticides (organophosphorus, organochlorine, carbamates, and pyrethroids) on thin-layer chromatographic (TLC)/high-performance thin-layer chromatographic (HPTLC) plates. To realize high sensitivity and improved selectivity, several chromogenic reagents have been introduced. The physical properties of organic pesticides reported so far are also presented in tabular form. The colors produced on TLC plates due to reactions taking place between pesticides and spray reagents are illustrated in the form of chromatograms, and reaction mechanism is also presented.

     

Immobilization of Au nanoparticles on poly(glycidyl methacrylate)-functionalized magnetic nanoparticles for enhanced catalytic application in the reduction of nitroarenes and Suzuki reaction

We report a novel strategy for the synthesis of magnetic nanocomposite for highly efficient catalysis. Poly(glycidyl methacrylate) (PGMA) chains were grafted to the surface of magnetic nanoparticles (MNPs) through surface-initiated reversible addition-fragmentation chain transfer polymerization. Then, the oxirane rings in the PGMA chains were opened with 2,6-diamino pyridine (DAP) molecules as ligands to prepare the solid support. Finally, this magnetic nanocomposite was used for the immobilization of gold nanoparticles. Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, transmission electron microscopy, scanning electron microscopy, gel permeation chromatography, vibrating sample magnetometry, and atomic absorption spectroscopy were used for characterization of the catalyst. The loading of gold nanoparticles on the solid support was 0.52 mmol/g. The catalytic activity of the prepared catalyst (MNP@PGMA@DAP@Au) was evaluated for the reduction of nitro compounds and C–C coupling reaction in water. The catalyst can be easily recovered and reused seven times without significant loss of catalytic activity.     

Antitumor evaluation and 3D-QSAR studies of a new series of the spiropyrroloquinoline isoindolinone/aza-isoindolinone derivatives by comparative molecular field analysis (CoMFA)

In current study, antitumor activity of two series of the newly synthesized spiropyrroloquinoline isoindolinone and spiropyrroloquinoline aza-isoindolinone scaffolds was evaluated against three human breast normal and cancer cell lines (MCF-10A, MCF-7 and SK-BR-3) and compared with cytotoxicity values of doxorubicin and colchicine as the standard drugs. It was found that several compounds were endowed with cytotoxicity in the low micromolar range. Among these two series, compounds 6i, 6j, 6k and 7l, 7m, 7n, 7o containing 3-ethyl-1H-indole moiety were found to be highly effective against both cancer cell lines ranging from \(0.080 \pm 0.001\) to \(11.91 \pm 1.39\,\upmu \hbox {M}\) in comparison with the corresponding analogs. Compared with human cancer cells, the most potent compounds did not show high cytotoxicity against human breast normal MCF-10A cells. Generally, most of the evaluated compounds 6a–l and 7a–o series showed more antitumor activity against SK-BR-3 than MCF-7 cells. Moreover, comparative molecular field analysis (CoMFA) as a popular tools of three-dimensional quantitative structure–activity relationship (3D-QSAR) studies was carried out on 27 spiropyrroloquinolineisoindolinone and spiropyrroloquinolineaza-isoindolinone derivatives with antitumor activity against on SK-BR-3 cells. The obtained CoMFA models showed statistically excellent performance, which also possessed good predictive ability for an external test set. The results confirm the important effect of molecular steric and electrostatic interactions of these compounds on in vitro cytotoxicity against SK-BR-3.     

Facile route for the synthesis of benzothiazoles and benzimidazoles in the presence of tungstophosphoric acid impregnated zirconium phosphate under solvent‐free conditions

Rapid and efficient condensation reactions of o‐phenylenediamine and o‐aminothiophenol with various aldehydes were carried out using tungstophosphoric acid impregnated zirconium phosphate in solvent‐free conditions to afford the corresponding 2‐substituted arylbenzimidazole and arylbenzothiazole derivatives in good to excellent yields. This procedure constitutes a simple and practical green synthetic method for 2‐arylbenzimidazoles and 2‐arylbenzothiazoles and their structural analogs. Furthermore, the catalyst can be reused for several times but it will be less active. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:202–207, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20534     

The Synthesis of Hetero-Halogenated Derivatives of Phloroglucide Analogues[1]

A short synthesis of the title compounds is reported. Most of the compounds prepared were found to be active against a number of pathogenic microorganisms in vitro.