نتایج جستجو برای: inverse phase transfer catalyst

تعداد نتایج: 992446  

2004
Tomohiro Nakatani Keisuke Kinoshita Masato Miyoshi Parham Zolfaghari

Although a number of dereverberation methods have been reported, dereverberation is still a challenging problem especially when a single microphone is used. To overcome this problem, we proposed a harmonicity based dereverberation method (HERB). HERB can blindly estimate the inverse filter of a room transfer function based on the harmonicity of speech signals and dereverberate the signals. Howe...

Journal: :علوم و تکنولوژی پلیمر 0
مهرسا امامی رضا مهترانی منیرالسادات ساداتی فرزین هرمزی

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...

Journal: :Organic & biomolecular chemistry 2013
P Vijaya Babu Soumita Mukherjee Girdhar Singh Deora Keerthana Sarma Chennubhotla Raghavender Medisetti Swapna Yellanki Pushkar Kulkarni Shivashankar Sripelly Kishore V L Parsa Kiranam Chatti K Mukkanti Manojit Pal

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...

Journal: :Molecules 2008
Benoît Cossec Frédéric Cosnier Manuella Burgart

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...

2013
Richard Herchl Mario Waser

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...

Journal: :Journal of the American Chemical Society 2012
Robert J Phipps Kenichi Hiramatsu F Dean Toste

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...

Journal: :Journal of nuclear medicine : official publication, Society of Nuclear Medicine 2013
Lionel C Libert Xavier Franci Alain R Plenevaux Takashi Ooi Keiji Maruoka André J Luxen Christian F Lemaire

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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