Suzuki aryl cross-coupling chemistry using derivatives of 1,1,2,2,9,9,10,10-octafluoro[2.2]paracyclophane

An exploration into the scope of Suzuki aryl cross-coupling chemistry using derivatives of 1,1,2,2,9,9,10,10-octafluoro[2.2]paracyclophane is reported. The coupling of 4-iodo-1,1,2,2,9,9,10,10-octafluoro[2.2]paracyclophane with various aryl boronic acids and boronic acid pinacol esters was successful, with the exception of very sterically demanding systems, such as mesityl. The synthesis of the previously unreported 1,1,2,2,9,9,10,10-octafluoro[2.2]paracyclophanyl-4-boronic acid is described, together with various Suzuki aryl cross-coupling reactions of this new system. Using standard Suzuki methodology, it was possible to prepare dicyclophanes bearing two octafluoro[2.2]paracyclophane units separated by both one and two benzene rings.     

Effect of particle size of mineral fillers on polymer-matrix composite shielding materials against ionizing electromagnetic radiation

Filler particle size is an important particle that effects radiation attenuation performance of a composite shielding material but the effects of it have not been exploited so far. In this study, two mineral (hematite–ilmenite) with different particle sizes were used as fillers in a polymer-matrix composite and effects of particle size on shielding performance was investigated within a widerange of radiation energy (0–2000 keV). The thermal and structural properties of the composites were also examined. The results showed that as the filler particle size decreased the shielding performance increased. The highest shielding performance reached was 23% with particle sizes being between <7 and <74 µm.

     

Studies on 1,4-Quinone Derivatives Exhibiting Anti-Leukemic Activity along with Anti-Colorectal and Anti-Breast Cancer Effects

Colorectal cancer (CRC), breast cancer, and chronic myeloid leukemia (CML) are life-threatening malignancies worldwide. Although potent therapeutic and screening strategies have been developed so far, these cancer types are still major public health problems. Therefore, the exploration of more potent and selective new agents is urgently required for the treatment of these cancers. Quinones represent one of the most important structures in anticancer drug discovery. We have previously identified a series of quinone-based compounds (ABQ-1-17) as anti-CML agents. In the current work, ABQ-3 was taken to the National Cancer Institute (NCI) for screening to determine its in vitro antiproliferative effects against a large panel of human tumor cell lines at five doses. ABQ-3 revealed significant growth inhibition against HCT-116 CRC and MCF-7 breast cancer cells with 2.00 µM and 2.35 µM GI₅₀ values, respectively. The MTT test also showed that ABQ-3 possessed anticancer effects towards HCT-116 and MCF-7 cells with IC₅₀ values of 5.22 ± 2.41 μM and 7.46 ± 2.76 μM, respectively. Further experiments indicated that ABQ-3 induced apoptosis in both cell lines, and molecular docking studies explicitly suggested that ABQ-3 exhibited DNA binding in a similar fashion to previously reported compounds. Based on in silico pharmacokinetic prediction, ABQ-3 might display drug-like features enabling this compound to become a lead molecule for future studies.     

Synthesis and characterization of polyaniline/silicon dioxide composites and preparation of conductive films

The focus of this study was to synthesize the inherently conductive polymer polyaniline using an optimized process to prepare polyaniline/silicon dioxide (PANI/SiO₂) composites by in situ polymerization and ex situ solution mixing. PANI and PANI/SiO₂ composite films were prepared by drop‐by‐drop and spin coating methods. The electrical conductivities of HCl doped PANI film and PANI/SiO₂ composite films were measured according to the standard four‐point‐probe technique. The composite films exhibited an increase in electrical conductivity over neat PANI. PANI and PANI/SiO₂ composites were also investigated by spectroscopic methods including UV‐Vis, FT‐IR, and Photoluminescence. UV‐Vis and FT‐IR studies showed that SiO₂ particles affect the quinoid units along the polymer backbone and indicate strong interactions between the SiO₂ particles and the quinoidal sites of PANI (doping effect). The photoluminescence properties of PANI and PANI/SiO₂ composites were studied and the PANI/SiO₂ composites showed increased intensity as compared to neat PANI. The increase of conductivity of PANI/SiO₂ composite may be partially due to the doping or impurity effect of SiO₂ where the silicon dioxides compete with chloride ions. The morphology of particles and films were examined by a scanning electron microscope (SEM). SEM measurements indicated that the SiO₂ were well dispersed and isolated in composite films. Copyright © 2009 John Wiley & Sons, Ltd.     

Bioleaching of Zinc and Iron from Steel Plant Waste using <Emphasis Type="Italic">Acidithiobacillus Ferrooxidans</Emphasis>

The bacterial leaching of zinc and iron from solid wastes at the Isdemir iron and steel plant has been investigated using Acidithiobacillus ferrooxidans as the bacterial agent. The effects of a range of operational parameters, including particle size, solids concentration and pH, on the efficiency of the bioleaching process were investigated. In each test, several variables were determined to assess the efficiency of leaching, including slurry pH and redox potential, temperature, bacteria population and concentrations of zinc and iron in solution. Experimental results demonstrated that pulp solids concentration, slurry pH and solids particle size were all important parameters in the bacterial leaching process. Maximum extraction was achieved at pH values around 1.3 and a solids concentration of 1% w/v, with 35% of the Zn content and 37% of the Fe being dissolved.     

A New Series of Indeno[1,2-c]pyrazoles as EGFR TK Inhibitors for NSCLC Therapy

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death throughout the world. Due to the shortcomings of traditional chemotherapy, targeted therapies have come into prominence for the management of NSCLC. In particular, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) therapy has emerged as a first-line therapy for NSCLC patients with EGFR-activating mutations. In this context, new indenopyrazoles, which were prepared by an efficient microwave-assisted method, were subjected to in silico and in vitro assays to evaluate their potency as EGFR TK-targeted anti-NSCLC agents. Compound 4 was the most promising antitumor agent towards A549 human lung adenocarcinoma cells, with an IC₅₀ value of 6.13 µM compared to erlotinib (IC₅₀ = 19.67 µM). Based on its low cytotoxicity to peripheral blood mononuclear cells (PBMCs), it can be concluded that compound 4 exerts selective antitumor action. This compound also inhibited EGFR TK with an IC₅₀ value of 17.58 µM compared to erlotinib (IC₅₀ = 0.04 µM) and induced apoptosis (56.30%). Taking into account in silico and in vitro data, compound 4 stands out as a potential EGFR TKI for the treatment of NSCLC.     

An exploration of Suzuki aryl cross coupling chemistry involving [2.2]paracyclophane derivatives

Suzuki aryl cross coupling reactions using derivatives of [2.2]paracyclophane were examined. A variety of aryl boronic acids and pinacolate esters were successfully cross coupled with 4-bromo[2.2]paracyclophane under standard Suzuki conditions. Whilst an excellent tolerance for electron donating and withdrawing groups was observed, cross coupling reactions with highly sterically demanding borates (e.g. mesityl) were unsuccessful. The preparation and stability of the previously unreported [2.2]paracyclophanyl-4-boronic acid, -pinacolate ester and -dimethyl ester are described, along with the utility of these systems in Suzuki aryl cross coupling reactions. Application of this methodology led to a dicyclophane containing two [2.2]paracyclophane units separated by a 4-4' connected biphenyl spacer group.     

Preparation and wittig reactions of organotrifluoroborato phosphonium ylides

[reaction: see text] Potassium [(trifluoroboratophenyl)methyl]triphenylphosphonium chlorides have been prepared from the corresponding benzyl chlorides and PPh3. In the presence of 1.2 equiv of K2CO3 and various aldehydes, these mixed salts are easily converted to the corresponding unsaturated organotrifluoroborates via the intermediate phosphorus ylides. A protocol for a one-pot transformation has also been developed.     

Copper-catalyzed oxaziridine-mediated oxidation of C-h bonds

The highly regio- and chemoselective oxidation of activated C-H bonds has been observed via copper-catalyzed reactions of oxaziridines. The oxidation proceeded with a variety of substrates, primarily comprising allylic and benzylic examples, as well as one example of an otherwise unactivated tertiary C-H bond. The mechanism of the reaction is proposed to involve single-electron transfer to the oxaziridines to generate a copper-bound radical anion, followed by hydrogen atom abstraction and collapse to products, with regeneration of the catalyst by a final single-electron transfer event. The involvement of allylic radical intermediates was supported by a radical-trapping experiment with TEMPO.