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A rhodium(I)-catalyzed allenic Alder ene reaction to prepare cross-conjugated trienes has been discovered. The scope and limitations are currently being investigated, and the results obtained to date are reported on. This method shows enticing functional group compatibility by tolerating terminal and internal alkynes, hydroxyl, sulfonamide, ether, and diester groups. Progress has been made to increase the stereoselectivity of the olefinic side chain via an unprecendented iridium(I) catalyzed Alder-ene reaction. 相似文献
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Janni Mirosevich Gregoire Cardoen Brian Burke Tara Costich Kevin Sill 《Journal of polymer science. Part A, Polymer chemistry》2012,50(5):836-850
Cationic polymers have received much attention as promising nonviral vectors for gene transfer. However, development of polymers with low cell toxicities and high transfection efficiencies continue to be a significant problem and a major hurdle to their success. Poly‐D /L aspartate‐diethylenetriamine poly(D /L Asp‐DET) polymers were synthesized and evaluated as nonviral gene delivery agents. Poly(D /L Asp‐DET) polymers display endosome buffering capacity. The polymers condense plasmid DNA above N:P ratios of 1 and form polyplex particles of ~50–100 nm, with zeta potentials between neutral and +40 mV. Transmission electron microscopy shows the polyplexes to be uniform in size and shape. Polyplexes maintain the structural integrity of DNA following incubation in nucleases and also show high transfection efficiencies with minimal toxicity in both HCT‐116 and PC‐3 cell culture. However, it is found that these poly(D /L Asp‐DET)/DNA polyplexes immediately aggregate in salt and serum conditions, making them unsuitable for use in vivo. Therefore, the polyplexes were further modified by covalent addition of polyethylene glycol (PEG). Introduction of this second step produces PEG‐polyplexes of uniform size (below 100 nm), with neutral zeta potentials that are also stable in both salt and serum conditions. These results suggest poly(D /L Asp‐DET) cationic polymers as potentially safe and efficient nonviral gene delivery agents. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
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Brummond KM Chen H Fisher KD Kerekes AD Rickards B Sill PC Geib SJ 《Organic letters》2002,4(11):1931-1934
[reaction: see text] Treatment of alkynyl allenes with [Rh(CO)(2)Cl](2) results in a formal [2 + 2 + 1] cycloaddition reaction. This reaction occurs with complete regioselectivity for a variety of substrates affording only 4-alkylidene cyclopentenones in good yields. Moreover, seven-membered rings have been prepared in high yields. 相似文献
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A computer program, HALTAFALL, is described which calculates the equilibrium concentrations of the species in mixtures of any number of components, which can form any number of complexes and solid phases, provided concentrations (or partial pressures) can be used in the equilibrium calculations. Of course, the equilibrium constants must be known and enough data be given about the gross composition. Some applications are indicated. The flexible input rules make it applicable to a variety of problems. From the input information, the program itself devises an efficient plan for solving the simultaneous equations. The program also provides an efficient means of finding out which of many possible solid phases can actually appear in a certain equilibrium mixture. 相似文献
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57Fe Mössbauer effect measurements have been made on U x Fe100?x (x=32, 33.3, and 35) samples at 300 and 78 K. Laves phase structure was maintained for all three samples. Mössbauer spectra of the three samples were found to be a symmetric quadrupole doublet at 300 K. Such spectra were converted into a set of two overlapping six lines pattern at 78 K. The values of the hyperfine fields have been found to vary systematically with the iron content in the samples. The Curie temperatures, as determined by the ac susceptibility measurements, have been found to increase by increasing the amount of iron in the samples. 相似文献
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