نتایج جستجو برای: phase transfer catalyst
تعداد نتایج: 909786 فیلتر نتایج به سال:
this is a report on the study of high melt flow, highly isotactic polypropylene homopolymer synthesized in liquid monomer using a fifth generation ziegler-natta catalytic system. at highest catalyst productivity, the response of thecatalyst to hydrogen as chain transfer is studied. melt flow rate is controlled by hydrogen as chain transfer from 0.4 to 300 g/10min with changing the amount of hyd...
A series of 1,3-disubstituted pyrrolo[2,3-b]quinoxalines has been designed for the potential inhibition of PDE4 without inhibiting luciferase. A ligand/PTC (phase transfer catalyst) free intramolecular Heck cyclization strategy was used to prepare these compounds, some of which showed significant inhibition of PDE4B (IC50≈ 5-14 μM) and growth inhibition of oral cancer cells (CAL 27) but not inh...
A safe and simple method for methyl S-arylmercapturate synthesis is described. Thirteen such compounds, to be used afterwards in metabolism studies, have been obtained with yields ranging from 71 to 99.6%. These compounds were obtained using a sulfa-Michael addition and synthesized by adding the corresponding thiophenols to a mixture composed of methyl 2-acetamidoacrylate (MAA), potassium carbo...
The first phase-transfer catalyzed cyclopropanation reaction of chalcones using bromomalonates as the nucleophiles in a Michael Initiated Ring Closing reaction (MIRC) was developed. Key to success was the use of a free OH-containing cinchona alkaloid ammonium salt catalyst and carefully optimized liquid/liquid reaction conditions. The reaction performed well for electron neutral and electron de...
The use of a BINOL-derived phosphate as a chiral anionic phase-transfer catalyst in a nonpolar solvent allows the enantioselective fluorination of enamides using Selectfluor as the fluorinating reagent. We demonstrate that a wide range of stable and synthetically versatile α-(fluoro)benzoylimines can be readily accessed with high enantioselectivity. These compounds have the potential to be read...
UNLABELLED 6-(18)F-fluoro-L-dopa ((18)F-FDOPA) has proven to be a useful radiopharmaceutical for the evaluation of presynaptic dopaminergic function using PET. In comparison to electrophilic synthesis, the no-carrier-added (NCA) nucleophilic method has several advantages. These include much higher available activity and specific activity. Recently, we have described an NCA enantioselective synt...
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