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991.
《Arabian Journal of Chemistry》2014,7(5):793-799
New nanomeric 3-thioxo-5-methoxy-4,5-dihydro-6-methyl-9-unsubstituted/substituted-1,2,4-triazino[5,6-b]indoles (2a–c) and 3-thioxo-5-methoxy-4,5-dihydro-6,7-dihydroxy-1,2,4-triaino[5,6]-cyclobut-6-ene (3) were prepared via reaction of thiosemicarbazide with 5-unsubstitutedand/substituted-indol-2,3-diones and/or 3,4-dihydroxycyclobutane-1,2-dione in methanol–concentrated HCl at room temperature. A series of mercury(II)–ligand salts e.g. compound 4b and Hg(II) complexes 5a,b and 6 of cyclic Schiff base were prepared. Structures of these compounds were established by elemental analysis and spectral measurements. The redox characteristics of selected compounds were studied for use as chelating agents for stripping voltammetric determination of mercuric(II) ions in aqueous media. The compounds were also screened for their use as molluscicidal agents against Biomophalaria Alexandrina Snails responsible for Bilhariziasis. 相似文献
992.
S. K. Chattopadhyay 《合成通讯》2013,43(24):3033-3078
1,2- and 2,1-benzothiazines, for example, 1,2-benzothiazine-1,1-dioxides. 2,benzothiazine-2,2-dioxides, 1-alkyl/aryl-1,2-/2,1-benzothiazine-S-oxides, dibenzothiazine and polyheterocycle containing benzothiazine moiety are considered to be one of the privileged heterocyclic scaffolds with huge importances both in synthetic organic chemistry and medicinal chemistry especially in the drug industry. Numerous pioneering methodologies for asymmetric and non-asymmetric scaffold constructions have been developed. Comprehensive visions of different powerful methodologies for the synthesis of these scaffolds have been presented in this review. 相似文献
993.
Silvia Pérez‐Silanes Goutham Devarapally Enrique Torres Elsa Moreno‐Viguri Ignacio Aldana Antonio Monge Philip W. Crawford 《Helvetica chimica acta》2013,96(2):217-227
The electrochemical properties of 24 1,4‐dioxidoquinoxalin‐2‐yl ketone derivatives with varying degrees of anti‐Chagas activity were investigated in the aprotic solvent dimethylformamide (DMF) by cyclic voltammetry and first‐derivative cyclic voltammetry. For this group of compounds, the first reduction in DMF was either reversible or quasireversible and consistent with reduction of the N‐oxide functionality to form the radical anion. The second reduction process for these compounds was irreversible under the conditions used. The reduction potentials correlated well with molecular structure. Substitution in the 3‐, 6‐, and 7‐ positions of the quinoxaline ring by electron‐withdrawing substituents directly affected the ease of reduction and improved the biological activities of these compounds, whereas substitution by electron‐donating groups had the opposite effect. The electrochemical results, when combined with previous work on their mechanism of action against Chagas disease and their measured anti‐Chagas activities, indicated that the quinoxaline 1,4‐dioxide system serves as a promising starting point for chemical modifications aimed at improving the T. cruzi activity via a possible bioreduction mechanism. 相似文献
994.
Yuan‐Yuan Li Ping Liu Yang Tang Hong‐Mei Li Ya‐Ling Tang Xin‐Hua Liang Ya‐Jie Tang 《Helvetica chimica acta》2013,96(4):702-709
The four new cerebrosides 1 – 4 possessing a unique C18 9‐methylsphinga‐4,8‐dienine‐related moiety and a cyclic octapeptide, 5 , possessing alternating proline and glycine moietes were isolated from the Tuber indicum fermentation mycelium. Their structures were established on the basis of a spectroscopic analysis including NMR and HR‐ESI‐MS, as well as an acidic methanolysis experiment. To the best of our knowledge, the cerebrosides identified in the present study are quite different from those isolated from Tuber indicum fruiting bodies. Additionally, it was the first time that a cyclic peptide was isolated from the Tuber genus. 相似文献
995.
Cyclopropyl ester (8a-f) were synthesized by the cyclopropanation of chalcones (7a-e) in dry benzene using powdered sodium in 80-85% yield. Preparation of tetralone ester (4a-e), an intermediate for the synthesis of podophyllotoxin derivatives by Lewis acid (SnCl4) catalyzed cyclization of (8a-e) is also described here. 相似文献
996.
A. I. Mikaya E. A. Trusova V. G. Zaikin L. A. Zegel'man A. B. Urin N. P. Volinsky 《Journal of separation science》1984,7(11):625-628
This article describes a method that assists in structure determination of cyclic sulfides mixtures by GC/MS. The method involves the use of a gas-phase hydrodesulfurization microreactor (AP-56 catalyst, reaction temperture 300-315°C, hydrogen as a carrier and reagent gas) located between the capillary column (OV-17) and the mass spectrometer. The presence of a microreactor in such a position does not essentially affect the chromatographic separation achieved by using the capillary column. Combined analysis of the mass spectra registered for the original sulfides and the hydrodesulfurization products permits the structure determination of each effluent to be made more reliably. This is illustrated by the investigation of a reaction mixture containing the structural and geometric isomers of methyl-substituted thiabicyclononanes. 相似文献
997.
998.
Hongxia Luo Nanqiang Li Weijun He Zujin Shi Zhennan Gu Xihuang Zhou 《Journal of Solid State Electrochemistry》1998,2(6):432-436
Electrochemical behavior of (C70)2-p-tert-butylcalix [8] arene film on a glassy carbon electrode has been studied by cyclic voltammetry. Two pairs of reduction/reoxidation
waves were detected in a mixed solvent of acetonitrile and water containing tetra-n-butylammonium perchlorate as the supporting electrolyte.
Received: 12 January 1998 / Accepted: 22 February 1998 相似文献
999.
Horst Huck 《Journal of Solid State Electrochemistry》2002,6(8):534-539
Two types of non-integer electron-exchange numbers from uniform and reversible surface-redox reactions without side reactions
have been distinguished. The first being the apparent number, n
app, of the apparent faradaic charge corresponding to cyclovoltammetric peak areas above the interpolated baseline, and the second
the thermodynamically defined surface-redox valency, n', of Nernstian slopes of cyclovoltammetric peak potentials depending on different solution pH. An analytical expression has
been derived for n
app based on a simplified capacitive equivalent circuit and for n' using the potential-dependent free adsorption energies of the reactants involved. It should be pointed out that the different
experimental values of n
app and n' refer to the same integer number of electrons per molecule oxidized or reduced.
Electronic Publication 相似文献
1000.
Guang Gong 《Discrete Applied Mathematics》2006,154(18):2590-2598
Let p be a prime, q=pm and Fq be the finite field with q elements. In this paper, we will consider q-ary sequences of period qn-1 for q>2 and study their various balance properties: symbol-balance, difference-balance, and two-tuple-balance properties. The array structure of the sequences is introduced, and various implications between these balance properties and the array structure are proved. Specifically, we prove that if a q-ary sequence of period qn-1 is difference-balanced and has the “cyclic” array structure then it is two-tuple-balanced. We conjecture that a difference-balanced q-ary sequence of period qn-1 must have the cyclic array structure. The conjecture is confirmed with respect to all of the known q-ary sequences which are difference-balanced, in particular, which have the ideal two-level autocorrelation function when q=p. 相似文献