Search results for "Benzene derivatives"
showing 10 items of 44 documents
Mild, Fast, and Easy To Conduct MoCl5-Mediated Dehydrogenative Coupling Reactions in Flow
2018
A convenient and straightforward approach to performing oxidative coupling reactions in flow is presented. A collection of electron-rich benzene derivatives was subjected to this protocol, and the distinct utility of molybdenum pentachloride (MoCl5) is established. Using this unexplored protocol, biphenyls could be obtained in 21–91% isolated yield. This simple protocol opens a new chapter in reagent-mediated dehydrogenative coupling reactions, and yields are compared to classical approaches.
Synthesis and solid state structure for a series of poly(1-pyrrolylmethyl)benzene derivatives. Control of the interplaying π–π and C–H⋯π interactions?
2006
The syntheses of new hexa- and 1,2,4,5-tetra-1-pyrrolylmethyl-benzene (1 and 2, respectively) compounds and their crystal structures, along with those for the related disubstituted o-, m- and p-di-1-pyrrolylmethyl-benzene (3–5) derivatives are reported. The arrangements of molecules in the 1-D structure for 2–5 are controlled by the interplay of two different weak interactions: π–π and C–H⋯π (Ph) interactions. The absence of such interactions in the packing of 1 seems to be related to the arrangement of the pyrrolylmethyl arms with respect to the benzene core, which prevents the π cloud of the aromatic ring to be part of any intermolecular interaction. In addition, C–H⋯π (pyrrolyl) interact…
Downregulation of thioredoxin-1-dependent CD95 S-nitrosation by Sorafenib reduces liver cancer
2020
Hepatocellular carcinoma (HCC) represents 80% of the primary hepatic neoplasms. It is the sixth most frequent neoplasm, the fourth cause of cancer-related death, and 7% of registered malignancies. Sorafenib is the first line molecular targeted therapy for patients in advanced stage of HCC. The present study shows that Sorafenib exerts free radical scavenging properties associated with the downregulation of nuclear factor E2-related factor 2 (Nrf2)-regulated thioredoxin 1 (Trx1) expression in liver cancer cells. The experimental downregulation and/or overexpression strategies showed that Trx1 induced activation of nitric oxide synthase (NOS) type 3 (NOS3) and S-nitrosation (SNO) of CD95 rece…
Synthesis and antitumor activities of 1,2,3-triazines and their benzo- and heterofused derivatives
2017
1,2,3-Triazines are a class of biologically active compounds that exhibit a broad spectrum of activities, including antibacterial, antifungal, antiviral, antiproliferative, analgesic and anti-inflammatory properties. This review, which covers the literature from the end of last century to 2016, treats, through a comprehensive, systematic approach, the 1,2,3-triazine and related benzo- and hetero-fused derivatives possessing antitumor activity. Their efficacy, combined with a simple synthesis confers to these molecules a great potential as scaffold for the development of antitumor compounds.
Headspace–mass spectrometry determination of benzene, toluene and the mixture of ethylbenzene and xylene isomers in soil samples using chemometrics
2007
A simple and fast method has been developed for the determination of benzene, toluene and the mixture of ethylbenzene and xylene isomers (BTEX) in soils. Samples were introduced in 10 mL standard glass vials of a headspace (HS) autosampler together with 150 microL of 2,6,10,14-tetramethylpentadecane, heated at 90 degrees C for 10 min and introduced in the mass spectrometer by using a transfer line heated at 250 degrees C as interface. The volatile fraction of samples was directly introduced into the source of the mass spectrometer which was scanned from m/z 75 to 110. A partial least squares (PLS) multivariate calibration approach based on a classical 3(3) calibration model was build with m…
Melatonin protects human red blood cells from oxidative hemolysis: new insights into the radical-scavenging activity.
1999
Antioxidant activity of melatonin in human erythrocytes, exposed to oxidative stress by cumene hydroperoxide (cumOOH), was investigated. CumOOH at 300 microM progressively oxidized a 1% suspension of red blood cells (RBCs), leading to 100% hemolysis in 180 min. Malondialdehyde and protein carbonyls in the membrane showed a progressive increase, as a result of the oxidative damage to membrane lipids and proteins, reaching peak values after 30 and 40 min, respectively. The membrane antioxidant vitamin E and the cytosolic reduced glutathione (GSH) were totally depleted in 20 min. As a consequence of the irreversible oxidative damage to hemoglobin (Hb), hemin accumulated into the RBC membrane d…
Dimerization control in the self-assembly behavior of copillar[5]arenes bearing ω-hydroxyalkoxy groups.
2012
Two novel copillar[5]arenes bearing ω-hydroxyalkoxy groups are synthesized and their self-assembly properties are studied by (1)H NMR spectroscopy, specific viscosity, and X-ray measurements. The copillar[5]arene 2b bearing a 6-hydroxyhexyloxy group exhibits a reversible self-assembly behavior, leading to the formation of the self-inclusion monomer and hugging dimers. The reversible self-assembly behavior can be controlled by tuning solvent, temperature, guest, and H-bond interaction. However, the copillar[5]arene 2a bearing a short 4-hydroxybutyloxy group does not show such a self-assembly behavior to the formation of the self-inclusion monomer and hugging dimers.
Antitumoural properties of benzannelated seven-membered 5-fluorouracil derivatives and related open analogues. Molecular markers for apoptosis and ce…
2005
Attention is increasingly being focussed on the cell cycle and apoptosis as potential targets for therapeutic intervention in cancer. We prepared a series of bioisosteric benzannelated seven-membered 5-FU O,N-acetals to test them against the MCF-7 human breast cancer cell line. Benzo-fused seven-membered O,O-acetals or their acyclic analogues led to the expected 5-FU O,N-acetals (or aminals), in addition to six- and 14-membered aminal structures and acyclic compounds. All the cyclic aminals provoked a G0/G1-phase cell cycle arrest, whereas Ftorafur, a known prodrug of 5-FU, and 1-[2-(2-hydroxymethyl-4-nitrophenoxy)-1-methoxyethyl]-5-fluorouracil (11) induced an S-phase cell cycle arrest. Al…
Approaches to characterise chromatographic column performance based on global parameters accounting for peak broadening and skewness.
2009
Peak broadening and skewness are fundamental parameters in chromatography, since they affect the resolution capability of a chromatographic column. A common practice to characterise chromatographic columns is to estimate the efficiency and asymmetry factor for the peaks of one or more solutes eluted at selected experimental conditions. This has the drawback that the extra-column contributions to the peak variance and skewness make the peak shape parameters depend on the retention time. We propose and discuss here the use of several approaches that allow the estimation of global parameters (non-dependent on the retention time) to describe the column performance. The global parameters arise f…
Comparative evaluation of liquid chromatography versus gas chromatography using a β-cyclodextrin stationary phase for the determination of BTEX in oc…
2009
An HPLC method for the determination of benzene, toluene, ethylbenzene and o-xylene, m-xylene and p-xylene in occupational environments was developed and compared with a GC-MS method. Chromatographic analysis using a beta-cyclodextrin stationary phase was performed after active and passive air sampling by adsorption on activated charcoal and pressurized fluid extraction. The analytes were completely separated and quantified using both methods, although GC-MS provided better resolutions and lower detection limits than HPLC. The HPLC method was unsuccessfully applied to the determination of benzene in real samples because its sensitivity was too low. Both methods were applied to the analysis …