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211.
Three scaffolds of benzimidazoles, bis-benzimidazoles, and bis-benzimidazole-dihydroquinoxalines were synthesized via Ugi/de-protection/cyclization methodology. Benzimidazole forming ring
closure was enabled under microwave irradiation in the presence of 10% TFA/DCE. The methodology demonstrates the utility of
2-(N-Boc-amino)-phenyl-isocyanide for the generation of new molecular diversity. 相似文献
212.
A series of 2′‐arenesulfonyloxy‐5‐benzylidene‐thiazolidine‐2,4‐diones (TZDs) were synthesized and examined for their antiproliferative effects on a panel of carcinoma cell lines. Our results indicated that initial synthesis of 5‐[2′‐hydroxybenzylidene]‐2,4‐thiazolidinone (9) by Knoevenagel condensation followed by nucleophilic substitution with arylsulfonyl chlorides exhibited superior efficiency to the alternative synthetic route. Among tested compounds, only 8c and 8e showed significant antiproliferative activity against PC‐3 and BT474 cells with GI50 values of 8.4 and 20.6 μM, respectively. SKHep cells displayed interesting structure‐activity relationships in response to TZD derivatives treatment. Alkyl group‐substituted TZD analogs such as 8a (4‐Me, GI50, 9.4 μM) and 8k (4‐iso‐propyl, GI50, 9.8 μM) revealed better antiproliferative activity than those with bulkier alkyl groups. On the other hand, halogen‐substituted TZD analogs 8c, 8h, and 8i showed better antiproliferative activity against H460 cell line. Together, the new synthesized TZD derivatives 8a , 8b , 8c , 8d , 8e , 8f , 8g , 8h , 8i , 8j , 8k , 8l , 8m , 8n , 8o , 8p exhibited appreciable antiproliferative activity worth for further study. 相似文献
213.
Sherrod L. Maxwell Brian K. Culligan Angel Kelsey-Wall Patrick J. Shaw 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(1):339-347
A new rapid method for the determination of actinides in food samples has been developed at the Savannah River Site Environmental
Lab (Aiken, SC, USA) that can be used for emergency response or routine food samples. If a radiological dispersive device
or improvised nuclear device event occurs, there will be a urgent need for rapid analyzes of many different environmental
matrices, as well as food samples, to support dose mitigation and protect general populations from radioactivity that may
enter the food chain. The recent accident at Fukushima nuclear power plant in March, 2011 reinforces the need to have rapid
analyzes for radionuclides in environmental and food samples. The new method to determine actinides in food samples utilizes
a furnace ashing step, a rapid sodium hydroxide fusion method, a lanthanum fluoride matrix removal step, and a column separation
process with stacked TEVA, TRU, and DGA resin cartridges. The furnace ashing and rapid fusion steps are performed in relatively
inexpensive, reusable zirconium crucibles. Alpha emitters are prepared using rare earth micro precipitation for counting by
alpha spectrometry. The method showed high chemical recoveries and effective removal of interferences. The determination of
actinides in food samples can be performed in less than 8 h for 10 g samples with excellent quality for emergency samples
using short count times. Larger food samples (100 g) may be processed in 24 h or less. The rapid fusion technique is a rugged
sample digestion method that ensures that any refractory actinide particles are effectively digested. This method can be used
to meet the derived intervention level guidelines recommended by the U.S. Food and Drug Administrations. 相似文献
214.
High-density silicon and silicon nitride cones 总被引:1,自引:0,他引:1
High-density cone-shaped silicon and silicon nitride have been synthesized on Si(1 0 0) substrates via plasma-assisted hot-filament chemical vapor deposition using a gas mixture of nitrogen, hydrogen and methane. Aligned silicon cones containing 3–10 at% C and N have been formed with less than 1 h growth. Further growth can lead to the increase of cone size and density, as well as to the formation of polycrystalline silicon nitride films on the tip and surface. The formation of these materials is thought to be due to the remodification of Si substrates under the effect of plasma and active C and N species. Different nucleation and growth styles were obtained under different growth conditions and reactive gas mixtures. 相似文献
215.
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217.
Hung‐Te Chang Kuo‐Chen Chiang Fung Fuh Wong Chun‐Sheng Huang Yang‐Ming Liao Wen‐Fa Kuo Shaw‐Bing Won Mou‐Yung Yeh 《Heteroatom Chemistry》2007,18(4):438-442
The synthesis of potential fluorescent active 4‐(5‐aryl‐1,3,4‐oxadiazol‐2‐yl)phenylhydrazine derivatives was accomplished in three steps. The key step was the dehydration cyclization of 1,2‐diacylhydrazines to form the 1,3,4‐oxadiazole ring by use of acetic anhydride/perchloric acid mixture as the dehydrating agent. The sydnone moiety served as the masked hydrazines, which could be demasked by HCl for further application. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:438–442, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20318 相似文献
218.
219.
Lucas C. Moore Anna Lo Jason S. Fell Matthew R. Duong Jose A. Moreno Barry E. Rich Martin Bravo Dr. James C. Fettinger Lucas W. Souza Prof. Marilyn M. Olmstead Prof. Kendall N. Houk Prof. Jared T. Shaw 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(52):12214-12220
Diastereoselective Lewis acid-mediated additions of nucleophilic alkenes to N-sulfonyl imines are reported. The canonical polar Felkin–Anh model describing additions to carbonyls does not adequately describe analogous additions to N-sulfonyl imines. Herein, we describe the development of conditions to produce both syn and anti products with high diastereoselectivity and good yields. A stereoelectronic model consistent with experimental outcomes is also proposed. 相似文献
220.