排序方式: 共有15条查询结果,搜索用时 15 毫秒
1.
新试剂3,5—二溴—4—偶氮8—羟基喹啉苯基荧光酮光度法测定微量铝 总被引:9,自引:0,他引:9
在溴化十六烷基三甲胺(CTMAB)存在下,PH6,0的HAc-NaAc缓冲介质中,铝与新试剂3,5-二溴-4-偶氮8-羟基喹啉苯基荧光酮形成红色三元胶束配合物,最大吸收波长位于564nm,表观摩尔吸光系数ε为1.35×10^5.mol^-1.cm^-1,铝浓度在0~5μg/25mL范围内符合比耳定律,拟定的方法用于铝铁黄铜中微量铝的测定,结果满意。 相似文献
2.
A new synthesis for (+)-casuarine (1) and its 6,7-diepi isomer (15) in a stereocontrolled manner, is reported herein. An appropriately protected polyhydroxylated pyrrolidine, such as (2R,3R,4R,5R)-3,4-dibenzyloxy-2′-O-tert-butyldiphenylsilyl-2,5-bis(hydroxymethyl)pyrrolidine (3, protected DMDP), easily available from d-fructose, was chosen as the chiral starting material. Compounds 1 and 15 were obtained from 3, in seven steps, in a 23.2 and 20.5% overall yields, respectively. 相似文献
3.
Preparation and characterization of slice-like Cu2(OH)3NO3 superhydrophobic structure on copper foil
Superhydrophobic structure was prepared on copper foil via a facile solution-immersion method. Thus slice-like Cu2(OH)3NO3 crystal was prepared on the surface of the copper foil by sequential immersing in an aqueous solution of sodium hydroxide and cupric nitrate. And the superhydrophobic structure was obtained by modifying the slice-like Cu2(OH)3NO3 crystal with 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS-17). The morphologies, chemical compositions and states, and hydrophobicity of the surface-modifying films on the copper foil substrates were analyzed by means of scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and water contact angle measurement. Moreover, the thermal stability of the slice-like structure was also evaluated using thermogravimetric analysis (TGA). It was found that roughening of the copper foil surface helped to increase the hydrophobicity to some extent, but no superhydrophobicity was obtained unless the slice-like Cu2(OH)3NO3 crystal formed on the Cu substrate was modified with 1H,1H,2H,2H-perfluorodecyltriethoxysilane. Besides, the superhydrophobicity of the FAS-17-modified slice-like Cu2(OH)3NO3 structure was closely related to the surface morphology. And this hydrophobic structure retained good superhydrophobic stability at elevated temperature and in long-term storage as well, which should be critical to the application of Cu-matrix materials in engineering. 相似文献
4.
Photooxygenation of Furylalkylamines: Easy Access to Pyrrolizidine and Indolizidine Scaffolds
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Dr. Dimitris Kalaitzakis Myron Triantafyllakis Manolis Sofiadis Dr. Dimitris Noutsias Prof. Dr. Georgios Vassilikogiannakis 《Angewandte Chemie (International ed. in English)》2016,55(14):4605-4609
A highly adaptable method targeting the ubiquitous and very important pyrrolizidine and indolizidine scaffolds is presented. The general synthetic utility of the method is underscored by its application to the rapid and easy synthesis of five natural products starting from readily accessible alkylfuran precursors. These unprotected primary furylalkylamines are subjected to photooxygenation conditions, which initiate a complex cascade reaction sequence concluding with the production of high value motifs. This sequence can be tailored to need by varying the choice of both photosensitizer and base additive. 相似文献
5.
Subban Kathiravan 《Tetrahedron letters》2009,50(45):6116-6120
A one-pot synthesis of ferrocene-grafted dispiropyrrolidine/pyrrolizidine scaffolds has been accomplished in good yields through a facile 1,3-dipolar cycloaddition of various azomethine ylides derived from diketones and secondary amino acids with Baylis-Hillman adduct derived from ferrocene carbaldehyde. The regiochemical and stereochemical outcomes of the cycloaddition reaction were ascertained by X-ray crystallographic studies of one of the cycloadducts. 相似文献
6.
I. M. Skvortsov 《Chemistry of Heterocyclic Compounds》2006,42(10):1247-1266
The cis-trans conversion in pyrrolizidines and the deciding effect of steric factors on their conformational equilibrium are
discussed. Work on the synthesis and characteristics of sterically strained pyrrolizidines is analyzed and discussed. It is
shown that such compounds (predominantly trans-fused) have a series of features in their properties that greatly distinguish
them from unstrained pyrrolizidines. The first results from study of the thermodynamics of cis-trans conversion of the pyrrolizidine
bicycle are summarized.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1466, October, 2006. 相似文献
7.
Synthesis of Pyrrolidines and Pyrrolizidines with α‐Pseudoquaternary Centers by Copper‐Catalyzed Condensation of α‐Diazodicarbonyl Compounds and Aryl γ‐Lactams
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Dr. Sébastien Goudedranche Dr. Céline Besnard Léo Egger Prof. Jérôme Lacour 《Angewandte Chemie (International ed. in English)》2016,55(44):13775-13779
N‐aryl γ‐lactams react intermolecularly with acceptor–acceptor diazo reagents, usually dicarbonyl compounds, in a copper‐catalyzed process to yield functionalized pyrrolidines with α‐pseudoquaternary centers. As 1,2‐acyl or ‐phosphoryl migration is preferred, single regioisomers are obtained. Furthermore, in the presence of a Lewis acid, subsequent Friedel–Crafts reactions yield tricyclic pyrrolizidines in excellent yields (90–96 %) and diastereoselectivities (up to >20:1). 相似文献
8.
Highly Enantioselective Intramolecular 1,3‐Dipolar Cycloaddition: A Route to Piperidino‐Pyrrolizidines
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Dr. Srinivasa Rao Vidadala Christopher Golz Prof. Dr. Carsten Strohmann Dr. Constantin‐G. Daniliuc Prof. Dr. Herbert Waldmann 《Angewandte Chemie (International ed. in English)》2015,54(2):651-655
Enantioselective catalytic intermolecular 1,3‐dipolar cycloadditions are powerful methods for the synthesis of heterocycles. In contrast, intramolecular enantioselective 1,3‐dipolar cycloadditions are virtually unexplored. A highly enantioselective synthesis of natural‐product‐inspired pyrrolidino‐piperidines by means of an intramolecular 1,3‐dipolar cycloaddition with azomethine ylides is now reported. The method has a wide scope and yields the desired cycloadducts with four tertiary stereogenic centers with up to 99 % ee. Combining the enantioselective catalytic intramolecular 1,3‐dipolar cycloaddition with a subsequent diastereoselective intermolecular 1,3‐dipolar cycloaddition yielded complex piperidino‐pyrrolizidines with very high stereoselectivity in a one‐pot tandem reaction. 相似文献
9.
A series of C-7 modified analogues of casuarine have been synthesized from sugar-derived nitrone and assayed against various glycosidases. Introduction of C-7 aminomethyl or amide group led to sharp decrease of the inhibitory activities. 相似文献
10.
邻硝基苯基荧光酮-钛-吐温-40体系分光光度研究及硅铁合金中钛的测定 总被引:5,自引:1,他引:4
系统研究邻硝基苯基荧光酮与钛的显色反应,试验多种表面活性剂对体系的作用及相应的光度性质,从而确定Ti(Ⅳ)-ONPF-Tween-40为较佳体系,在0.084-0.15mol/L HCl介质中形成紫红色配合物,其波长在530nm处的表观摩尔吸光系数ε为1.79×10^5L·mol^-1·cm^-1,配合物组成中Ti:ONPF=1:4,钛浓度在0-1.2μg/10mL范围内服从比耳定律。应用于直接测定硅铁合金中钛,结果满意。 相似文献