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91.
Single‐step synthesis of a radically polymerizable 1,1′‐bi‐2‐naphthol derivative for asymmetric catalysis 下载免费PDF全文
A new polymerizable 1,1′‐bi‐2‐naphthol derivative for polymer‐supported catalytic asymmetric synthesis is presented. The synthesis is conducted within a single reaction step, which is a major advantage over other approaches presented in the literature. The ligand‐bearing polymer is prepared through copolymerization with N‐isopropylacrylamide. Preliminary experiments on the utility in catalytic asymmetric alkylation reactions reveal the accessibility and activity of the polymer‐attached catalysts. The stereoselectivity of the reaction is found to be somewhat lower than for reactions performed in the presence of free 1,1′‐bi‐2‐naphthol, and thus requires further optimization. The enantiomeric excess of the reaction products was determined via 1H NMR spectroscopy after chiral derivatization with (R)‐α‐methylbenzyl isocyanate. © 2015 Society of Chemical Industry 相似文献
92.
Forgotten monomers: isotactic polymers from N‐benzyl‐3‐methylenepyrrolidin‐2‐one via free radical polymerization 下载免费PDF全文
N‐Benzyl‐3‐methylenepyrrolidin‐2‐one ( 3 ) was synthesized and homopolymerized under free radical conditions. The configurational microstructure of poly(N‐benzyl‐3‐methylenepyrrolidin‐2‐one) ( 4 ) is isotactic with a minor tendency to syndiotacticity. Monomer 3 was also homopolymerized in water in the presence of methylated β‐cyclodextrin. The glass transition temperature of 4 of 124 °C was compared with the lower value of 61 °C of the ring‐opened analogue poly(N‐benzyl‐N‐ethylacrylamide). © 2015 Society of Chemical Industry 相似文献
93.
Alkylation of N‐vinylpyrrolidone using lithium diisopropylamide and bis(2‐bromoethyl) ether was carried out to obtain 3‐(2‐(2‐bromoethoxy)ethyl)‐1‐vinyl‐2‐pyrrolidone ( 2 ). The derivative 2 represents a versatile starting molecule for further modification via nucleophilic displacement yielding, for example, the bicyclic 2‐vinyl‐8‐oxa‐2‐azaspiro[4.5]decan‐1‐one ( 4 ) or the ammonium salt 3‐diethoxy‐N,N′‐((dimethylbenzyl)ammonium bromide)‐1‐vinyl‐2‐pyrrolidone ( 10 ). Via free radical polymerization of 4 and 10 , the corresponding homopolymers were obtained. Copolymerization of 4 and 10 with N,N′‐diethylacrylamide yielded water‐soluble materials. The thermosensitive solubility of copolymers poly[(2‐vinyl‐8‐oxa‐2‐azaspiro[4.5]decan‐1‐one)‐co‐(N,N′‐diethylacrylamide)] and poly[(3‐diethoxy‐N,N′‐((dimethylbenzyl)ammonium bromide)‐1‐vinyl‐2‐pyrrolidone)‐co‐(N‐vinylpyrrolidone)] in water was investigated. © 2015 Society of Chemical Industry 相似文献
94.
The synthesis of the 4‐(dialkylamino)pyridine derivative 3‐(4‐(pyridin‐4‐yl)piperazin‐1‐yl)propyl methacrylate and its copolymerization with n‐butyl methacrylate are presented. The catalytic activity was evaluated in the acylation of tert‐butanol with acetic anhydride yielding tert‐butyl acetate. It is observed that the activity of polymer‐attached 4‐(dimethylamino)pyridine analogues correlates remarkably well with the chemical shift of the β‐pyridyl protons. Differences in catalytic efficiency result from distinct electronic densities of the pyridine ring, while embedding the catalytically active moiety into a polymeric structure has nearly no deleterious effect on the performance. © 2015 Society of Chemical Industry 相似文献
95.
Raddatz S Marcello M Kliem HC Tröster H Trendelenburg MF Oeser T Granzow C Wiessler M 《Chembiochem : a European journal of chemical biology》2004,5(4):474-482
The synthesis of a new ortho-carborane derivative, tetracarboranylketone 4, is reported here. Ketone 4 was prepared from a tetraalkynylated ketone by the addition of decaborane. The keto group was then easily modified to yield the glycosides 17alpha and 18beta, which contain glucose or galactose, respectively, and the nucleotide 13b. In addition to ketone 4, which is acyclic, cyclic ketone 8 was also synthesised. X-ray diffraction analysis of compound 4 indicated the presence of two toluene guest molecules per molecule of the host compound. Furthermore, compound 4 displays a rather low cytotoxicity. These novel products can be used as building blocks to create a new class of biomolecules containing high-density carborane clusters. Such molecules may constitute powerful tools for applications like Boron Neutron Capture Therapy or Energy-Filtering Transmission Electron Microscopy. 相似文献
96.
Katherine A. Buzzard Simon A. Broadley Helmut Butzkueven 《International journal of molecular sciences》2012,13(10):12665-12709
Multiple sclerosis is a potentially debilitating disease of the central nervous system. A concerted program of research by many centers around the world has consistently demonstrated the importance of the immune system in its pathogenesis. This knowledge has led to the formal testing of a number of therapeutic agents in both animal models and humans. These clinical trials have shed yet further light on the pathogenesis of MS through their sometimes unexpected effects and by their differential effects in terms of impact on relapses, progression of the disease, paraclinical parameters (MRI) and the adverse events that are experienced. Here we review the currently approved medications for the commonest form of multiple sclerosis (relapsing-remitting) and the emerging therapies for which preliminary results from phase II/III clinical trials are available. A detailed analysis of the molecular mechanisms responsible for the efficacy of these medications in multiple sclerosis indicates that blockade or modulation of both T- and B-cell activation and migration pathways in the periphery or CNS can lead to amelioration of the disease. It is hoped that further therapeutic trials will better delineate the pathogenesis of MS, ultimately leading to even better treatments with fewer adverse effects. 相似文献
97.
Helmut Richter Dr. rer. nat. Horst W. Tamler Dr. rer. nat. 《JOM Journal of the Minerals, Metals and Materials Society》1994,46(10):46-47
A new on-line texture-analyzing system and its application to nondestructive r value determination is discussed. In addition to providing a brief theoretical background and describing the instrumental set-up, the article presents off-line measurements with this equipment and demonstrates the high accuracy of the determined r-values. A special feature of the unit is the possibility to simultaneously measure the most important r values—r0, r45, r90, and rm. 相似文献
98.
99.
Markus W. Laimer Julia Engl Alexander Tschoner Susanne Kaser Andreas Ritsch Tobias Tatarczyk Markus Rauchenzauner Helmut Weiss Franz Aigner Josef R. Patsch Christoph F. Ebenbichler 《Lipids》2009,44(12):1125-1130
Obesity is associated with lipid abnormalities leading to an increased morbidity and mortality from atherosclerotic disease. Lipid transfer proteins such as Cholesteryl Ester Transfer Protein (CETP) and Phospholipid Transfer Protein (PLTP), and lipases such as lipoprotein lipase (LPL) and hepatic lipase (HL) are involved in the pathogenesis of the obesity associated proatherogenic dyslipidemia. Nineteen severely obese female subjects undergoing laparosopic gastric banding participated in this prospective study. Subjects were examined with respect to body composition, lipid profile, CETP, PLTP, LPL and HL before and 1 year after surgical treatment. Mean weight loss was 22.2 kg, mainly due to losses in the fat depots. Triglycerides decreased and HDL2-C increased significantly. In respect to transfer proteins mean CETP mass decreased from 1.82 to 1.71 μg mL?1 (P = 0.043) and mean PLTP activity was reduced from 7.15 to 6.12 μmol mL?1 h?1 (P = 0.002), in parallel. In addition, both mean LPL activity and mean HL activity tended to decrease from 297 to 248 nmol mL?1 h?1 for LPL (P = 0.139) and from 371 to 319 nmol mL?1 h?1 for HL (P = 0.170), respectively. We conclude that weight loss induced by bariatric surgery is associated with the amelioration of the obesity-associated dyslipidemic state. This improvement may be attributable to decreased mass and action of the adipocyte tissue derived lipid transfer proteins CETP and PLTP. 相似文献
100.
Tobias Königer Thomas Rechtenwald Ihab Al-Naimi Thomas Frick Michael Schmidt Helmut Münstedt 《Journal of Coatings Technology and Research》2010,7(2):261-269
A CO2-laser treatment was used to improve the electrical conductivity of coatings of indium tin oxide (ITO) nanoparticles on flexible
polyethyleneterephthalate (PET) substrates. The electrical conductivity and the transparency of CO2-laser-treated ITO nanoparticle coatings were characterized with regard to the application as transparent electrodes. Furthermore,
the stability of the electrical conductivity under oscillatory bending was investigated. A specific resistance of 0.12 Ω cm
is obtained by CO2-laser treatment without thermally damaging the PET film. The improvement of the electrical conductivity can be explained
by a slight sinter neck formation. For a film thickness of 3 μm, a sheet resistance of 400 Ω/□ and a transmission in the visible
range of 80% were achieved. The stability of the electrical conductivity of CO2-laser-treated ITO nanoparticle coatings under bending was investigated using a specially constructed device for the application
of various oscillatory bending loads. For a bending radius of 10 mm, the sheet resistance does not exceed 1000 Ω/□ after 300
bending cycles. Compared to commercial sputtered ITO coatings, CO2-laser-treated ITO nanoparticle coatings show a significant higher stability under oscillatory bending. 相似文献