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Acid Activation (acid + activation)
Selected AbstractsLewis Acid Activated Aza-Diels,Alder Reaction of N -(3-Pyridyl)aldimines: An Experimental and Computational StudyEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2010Francisco Palacios Abstract A combined theoretical and experimental study of a Povarov-type cycloaddition reaction suggests an asynchronous concerted process that is favored by double Lewis acid activation with BF3·Et2O; endo selectivity was observed in the reactions between N -(3-pyridyl)aldimines and styrene, cyclopentadiene, or indene, and substituted tetrahydro-1,5-naphthyridine derivatives were obtained in a regio- and stereoselective fashion. [source] Enantioselective Trifunctional Organocatalysts for Rate- Enhanced Aza-Morita,Baylis,Hillman Reactions at Room TemperatureADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 3 2009Jean-Marc Garnier Abstract A Brønsted acid-activated trifunctional organocatalyst, based on the BINAP scaffold, was used for the first time to catalyze aza-Morita-Baylis,Hillman reactions between N -tosylimines and methyl vinyl ketone with fast reaction rates and good enantioselectivity at room temperature. This trifunctional catalyst, containing a Lewis base, a Brønsted base, and a Brønsted acid, required acid activation to confer its enantioselectivity and rate improvement for both electron-rich and electron-deficient imine substrates. The role of the amino Lewis base of 1a was investigated and found to be the activity switch in response to an acid additive. The counterion of the acid additive was found to influence not only the excess ratio but also the sense of asymmetric induction. [source] Characterization and use of acid-activated montmorillonite-illite type of clay for lead(II) removalAICHE JOURNAL, Issue 9 2010John U. Kennedy Oubagaranadin Abstract The natural local deposits of montmorillonite-illite type of clay (MIC) were susceptible for acid activation. Raw clay was taken for experimentation, disintegrated on acid activation with sulfuric acid, which showed a particle size distribution. The montmorillonite and illite phases in the raw clay disappeared on acid activation and the activated clay, MIC(AA), showed with sodium-aluminum-silicate and beidellite phases apart from quartz (low) phase. The raw and acid-activated clays were characterized using X-ray powder diffractometry, X-ray fluorescence, Fourier transform infrared spectrometry, and energy dispersive X-ray, and their adsorption capacities were compared. When tested for adsorption of Pb(II) in aqueous solutions, the acid-activated clay showed about 50% increased adsorption than raw clay. Sips adsorption isotherm and pseudo-second-order kinetic models were found to be best for the batch adsorption data. Kinetic studies showed the existence of film diffusion and intraparticle diffusion. A two-stage batch adsorber was designed for the removal of Pb(II) from aqueous solutions. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Arachidonic acid activation of intratumoral steroid synthesis during prostate cancer progression to castration resistanceTHE PROSTATE, Issue 3 2010Jennifer A. Locke Abstract BACKGROUND De novo androgen synthesis and subsequent androgen receptor (AR) activation has recently been shown to contribute to castration-resistant prostate cancer (CRPC) progression. Herein we provide evidence that fatty acids (FA) can trigger androgen synthesis within steroid starved prostate cancer (CaP) tumor cells. METHODS Tumoral FA and steroid levels were assessed by GC,MS and LC,MS, respectively. Profiles of genes and proteins involved in FA activation of steroidogenesis were assessed by fluorescence microscopy, immunohistochemistry, microarray expression profiling and Western blot analysis. RESULTS In human CaP tissues the levels of proteins responsible for FA activation of steroid synthesis were observed to be altered during progression to CRPC. Further investigating this mechanism in LNCaP cells, we demonstrate that specific FA, arachidonic acid, is synthesized in an androgen-dependent and AR-mediated manner. Arachidonic acid is known to induce steroidogenic acute regulatory protein (StAR) in steroidogenic cells. When bound to hormone sensitive lipase (HSL), StAR shuttles free cholesterol into the mitochondria for downstream conversion into androgens. We show that arachidonic acid induces androgen production in steroid starved LNCaP cells coincidently in the same conditions that HSL and StAR are predominantly localized in the mitochondria. Furthermore, their activities are verified by a functional increase in mitochondrial uptake of cholesterol in this steroid starved environment. CONCLUSIONS We propose that this characterized arachidonic acid induced steroidogenesis mechanism significantly contributes to the activation of AR in CRPC progression and therefore recommend that fatty acid pathways be targeted therapeutically in progressing CaP. Prostate 70: 239,251, 2010. © 2009 Wiley-Liss, Inc. [source] | ||||||||||