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181.
Substitution‐Inert Polynuclear Platinum Complexes That Inhibit the Activity of DNA Polymerase in Triplex‐Forming Templates 下载免费PDF全文
Dr. Jaroslav Malina Prof. Nicholas P. Farrell Prof. Viktor Brabec 《Angewandte Chemie (International ed. in English)》2018,57(28):8535-8539
The formation of triple‐helical DNA is implicated in the regulation of gene expression. The triplexes are, however, unstable under physiological conditions so that effective stabilizers for the triplex formation are needed. Herein, we describe a new strategy for the stabilization of such triplexes that is based on antitumor substitution‐inert polynuclear platinum complexes (SI‐PPCs). These compounds were previously shown to bind to DNA through the phosphate clamp—a discrete mode of DNA–ligand recognition distinct from the canonical intercalation and minor‐groove binding. We have found that SI‐PPCs efficiently inhibit DNA synthesis by DNA polymerase in sequences prone to the formation of pyrimidine‐ and purine‐motif triplex DNAs. Moreover, the results suggest that SI‐PPCs are able to induce the formation of triple‐helical DNA between duplexes and strands that are not completely complementary to each other. Collectively, these data provide evidence that SI‐PPCs are very efficient stabilizers of triple‐stranded DNA that might exert their action by stabilizing higher‐order structures such as triple‐helical DNA. 相似文献
182.
Immobilized arylnitroso dienophiles were prepared and used in hetero Diels-Alder (HDA) reactions with a variety of dienes. Polymer-supported arylnitroso species were prepared on several linkers cleavable by different cleavage reagents and used for (i) optimization of reaction conditions for HDA reactions, (ii) evaluation of the reaction outcome with various dienes, (iii) comparison of relative reactivities of dienes, and (iv) assessment of the stability of HDA adducts toward cleavage conditions typically used in solid-phase preparation (TFA). The outcome of the HDA reactions has been evaluated for a set of 19 dienes, and the relative reactivities of dienes that yielded the expected HDA adducts were compared. Cleaved products were submitted to biological assays, and the results are reported. 相似文献
183.
Polymer-supported acylnitroso dienophiles were prepared and used in hetero Diels-Alder (HDA) reactions with a variety of dienes. The transient acylnitroso dienophiles were prepared in situ from immobilized hydroxamates, which were attached to solid supports via several linkers each cleavable by different cleavage reagents, and served for the synthesis of both N-unsubstituted and N-derivatized HDA adducts. Model compounds were used to (i) optimize reaction conditions for solid-supported HDA reactions, (ii) evaluate the outcome of the reactions with various dienes, (iii) compare relative reactivities of dienes, and (iv) assess the stability of HDA adducts toward cleavage conditions typically used in solid-phase syntheses. Cleaved products were submitted to biological assays, and the results are reported. The accompanying paper, focused on complementary arylnitroso HDA reactions, includes a comparison of both HDA reactions. 相似文献
184.
Base-catalyzed tandem carbon-carbon followed by nitrogen-nitrogen bond formations quantitatively converted N-alkyl-2-nitro-N-(2-oxo-2-aryl-ethyl)-benzenesulfonamides to 2H-indazoles 1-oxides under mild conditions. Triphenylphosphine or mesyl chloride/triethylamine-mediated deoxygenation afforded 2H-indazoles. 相似文献
185.
Yusubov MS Funk TV Chi KW Cha EH Kim GH Kirschning A Zhdankin VV 《The Journal of organic chemistry》2008,73(1):295-297
Preparation, structural characterization, and reactivity of 3-[bis(trifluoroacetoxy)iodo]benzoic acid and 3-[hydroxy(tosyloxy)iodo]benzoic acid, new recyclable iodine(III) reagents derived from 3-iodosylbenzoic acid, are described. The reduced form of these reagents, 3-iodobenzoic acid, can be easily recovered from the reaction mixtures using ion-exchange resin or basic aqueous workup followed by acidification with HCl. 相似文献
186.
The behaviour of enaminomalonates and their deprotection to amines under various reductive conditions is described. A new synthetic approach to N-aryl-N-acetyl-β-amino acids using heterogeneous catalytic hydrogenation has been discovered. 相似文献
187.
In this study, the aggregation dynamics of magic-sized CdTe quantum dots is investigated. The experiments show that the growth kinetics of the quantum dots is very sensitive to the Cd/Te ratio. The crossover from tellurium-rich to cadmium-rich conditions produces a very different aggregation pattern, which can be explained by the lack of formation of magic-sized nanoparticles during the reaction conditions. A simple simulation that includes both monomer-induced growth and aggregation growth is presented to reproduce the experimentally observed aggregation patterns. The simulation results strongly suggest that the experimental aggregation pattern can be reproduced if initially a double magic-sized distribution is assumed. The numerical data clearly show that the aggregation is enhanced by the dipole-dipole interaction. Simulations also suggest that the neck formation of the CdTe quantum dot aggregates is unlikely under the experimental conditions. The absence of neck formation is in agreement with the expectations during high-temperature synthesis. 相似文献
188.
189.
Wilkening M Iwaniak W Heine J Epp V Kleinert A Behrens M Nuspl G Bensch W Heitjans P 《Physical chemistry chemical physics : PCCP》2007,9(47):6199-6202
The microscopic Li diffusion parameters in the lithiated spinel Li4 + xTi5O12, which is on its way to become a commercially used anode material in Li ion batteries, are probed for the first time via nuclear magnetic resonance spectroscopy. 相似文献
190.
The properties of an infinite carbon chain (polyyne), an allotropic form of elemental carbon, are of importance in materials science as well as astronomy. The Raman active longitudinal optical (LO) frequencies are calculated with first-principles methods for oligoynes and polyyne and compared with experiments. Since traditional force constant scaling schemes fail in this case, we introduced a linear/exponential scaling scheme based on the exponential behavior of the carbon-carbon bond stretching force constant couplings in quasi-one-dimensional conjugated chains. The LO Raman active frequency is predicted at 1870-1877 cm-1. Our results provides further evidence for the assignment of the characteristic Raman peaks near 1850 cm-1 of the recently discovered long linear carbon chains encapsulated inside multiwalled or double-walled carbon nanotubes. 相似文献