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91.
Athanasios Markos Dr. Svatava Voltrová Vladimir Motornov David Tichý Dr. Blanka Klepetářová Dr. Petr Beier 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(32):7640-7644
N-Fluoroalkylated 1,2,3-triazoles in the presence of triflic acid or fluorosulfonic acid underwent a cascade reaction consisting of triazole protonation, ring opening, nitrogen elimination, sulfonate addition, HF elimination, and hydrolysis to furnish novel trifluoromethanesulfonyloxy- or fluorosulfonyloxy-substituted enamides, respectively, in a highly stereoselective fashion. The vinyl triflates underwent cross-coupling reactions to a variety of substituted enamides and serve as sources of the aminovinyl cations. In reactions with triflic acid, electron-rich triazoles afforded 2-fluoroalkylated oxazoles. 相似文献
92.
Tom Etrych Petr Chytil Markta Jelínkov Blanka íhov Karel Ulbrich 《Macromolecular bioscience》2002,2(1):43-52
The aim of this study was the synthesis, physico‐chemical characterization and preliminary evaluation of biological activity of novel polymer drugs based on conjugates of anti‐cancer drug doxorubicin (Dox) with water‐soluble polymer drug carriers based on N‐(2‐hydroxypropyl)methacrylamide (HPMA) copolymers. In the conjugates, Dox is attached to the polymer via a pH‐sensitive linkage susceptible to hydrolysis at pH ≈ 5–6, thus enabling intracellular Dox release. Seven Dox‐containing polymer conjugates differing in the length and structure of the single‐amino‐acid or oligopeptide spacer were synthesized (Gly, β‐Ala, 6‐aminohexanoyl, 4‐aminobenzoyl, GlyGly, GlyLeuGly, Gly‐DL ‐PheLeuGly) and the relationship between the spacer structure and the rate of in vitro Dox release was studied at various pH. The rate of Dox release at pH 5 (close to lysosomal pH) ranged from 70 to 96% of total Dox/48 h, depending on the spacer structure and being the highest for the conjugate containing the 6‐aminohexanoyl spacer. The rate of Dox release from most conjugates incubated at pH 7.4 (blood pH) was more than 10 times slower, ca. 4–10% of total Dox/48 h. Molecular weight of the polymer (25 000–115 000 g/mol) did not significantly influence the rate. The presence of lysosomal enzyme cathepsin B in incubation media increased the rate of Dox release from the conjugates with oligopeptide GlyLeuGly and Gly‐DL ‐PheLeuGly spacers by 15–30%, whereas the release from conjugates with other spacers remained unchanged. Cytotoxicity of all hydrazone conjugates for mouse EL‐4 T cell lymphoma cells was much higher and close to that of free Dox (IC50 ≈ 0.1–0.34 μg Dox/mL), in contrast to cytotoxicity of similar classic conjugates bearing Dox attached via an amide bond (IC50 ≈ 19 μg Dox/mL). 相似文献
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96.
Oxidative Catalysis Using the Stoichiometric Oxidant as a Reagent: An Efficient Strategy for Single‐Electron‐Transfer‐Induced Tandem Anion–Radical Reactions
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Ing. František Kafka Ing. Martin Holan M.Sc. Denisa Hidasová Dr. Radek Pohl Dr. Ivana Císařová Dr. Blanka Klepetářová Dr. Ullrich Jahn 《Angewandte Chemie (International ed. in English)》2014,53(37):9944-9948
Oxidative single‐electron transfer‐catalyzed tandem reactions consisting of a conjugate addition and a radical cyclization are reported, which incorporate the mandatory terminal oxidant as a functionality into the product. 相似文献
97.
Kuchar M Pohl R Klepetárová B Votruba I Hocek M 《Organic & biomolecular chemistry》2008,6(13):2377-2387
Synthesis of novel purine bases and nucleosides bearing unsubstituted or substituted cyclopropyl rings in position 6 is reported. Unsubstituted 6-cyclopropylpurines were efficiently prepared by cross-coupling reactions of 6-chloropurines with cyclopropylzinc chloride. 6-Vinylpurines underwent Cu-mediated cyclopropanations with ethyl diazoacetate to give 6-[(ethoxycarbonyl)cyclopropyl]purines that were further transformed to carboxylic acids, amides and alcohols. 6-Cyclopropylpurine ribonucleoside exerted a significant cytostatic effect while all substituted derivatives were inactive. 相似文献
98.
Zdenek Spichal Blanka Hegrova Zdenek Moravec Jiri Pinkas Marek Necas 《Polyhedron》2011,30(9):225-1627
Three large-bite diphosphine dioxide ligands were reacted with lanthanide salts to yield either molecular or polymeric complexes. The two flexible ligands gave bischelate complexes of general formulae [Ln(dppfO2)2Clx(NO3)2−x][FeCl4] and [Ln(dppdO2)2(NO3)2]NO3, where dppfO2 and dppdO2 are bis(diphenylphosphoryl)ferrocene and bis(diphenylphosphoryl)diphenyl ether, respectively. Reactions of the rigid bis(diphenylphosphoryl)benzene (dppbO2) with lanthanide salts yielded linear coordination polymers of a 1:1.5 metal-to-ligand stoichiometry. The compounds were studied by single crystal X-ray diffraction, IR spectroscopy, mass spectrometry, and TG/DSC techniques. 相似文献
99.
R. P. Agarwal Blanka Baculíková Jozef D?urina Tong Li 《Acta Mathematica Hungarica》2012,134(1-2):54-67
The objective of this paper is to offer sufficient conditions for the oscillation of all solutions and other asymptotic properties of the third-order nonlinear functional differential equation $$\left[a(t)\left[x''(t)\right]^{\gamma}\right]' =q(t)f \left(x\left[\tau(t)\right]\right)+p(t)h \left(x\left[\sigma(t)\right]\right)$$ with mixed arguments, where both cases ∫∞ a ?1/γ (s)?ds=∞ and ∫∞ a ?1/γ (s)?ds<∞ are dealt with. We deduce properties of the studied equations via new comparison theorems. Our results essentially improve and complement earlier ones. We also repair one interesting result of Grace et al. 相似文献
100.
Ramesh C. Rathi Pavla Kope
kov Blanka íhov Jindich Kope
ek 《Journal of polymer science. Part A, Polymer chemistry》1991,29(13):1895-1902
A new route for the synthesis of bioadhesive water soluble polymeric drug carriers has been developed. Novel monomers, namely, N-methacryloylglycylglycylgalactosamine (MA-Gly-Gly-GalN) [ 8 ], MA -Gly-Gly-FucN [ 9 ], MA -Gly-Gly-GlcN [ 10 ], and MA-Gly-Gly-ManN [ 11 ], and copolymers [ 12–16 ] based on N-(2-hydroxypropyl) methacrylamide (HPMA) containing different content of pendant saccharide moieties (galactosamine, fucosylamine, glucosamine, or mannosamine), were synthesized. Copolymerization parameters for the copolymerization of HPMA [M1] and MA-Gly-Gly-GalN [M2] have been determined (r1 = 0.82, r2 = 0.38). Bioadhesion studies with everted sacs of guinesa pig small intestine and colon in vitro demonstrated that HPMA copolymers containing side-chains terminated in fucosylamine bind selectively to the colonic tissue. The extent of binding was dependent on the fucosylamine content of copolymers. 相似文献