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931.
Tetrachloro-1, 2-benzoquinone and 2, 3-dichloro-1, 4-naphthoquinone react with a series of aryl and alkyl selenolate, generated either by the reaction of Grignard reagents and selenium powder or by the reduction of diselenides with NaBH4, to give 3, 6-diarylseleno-2, 5-dichloro-1, 4-benzoquinones 3 and 2, 3-diarylseleno-1, 4-naphthoquinones 4 in good yields. 相似文献
932.
Abstract A novel 1,1,10,10,19,19-hexamethyl-5,14,23-trimethoxy[3.3.3]metacyclophane (2) was prepared in 25% yield by Friedel–Crafts cyclization of 4-(2-methoxyphenyl)-2-methylbutan-2-ol (1) at ? 78 °C using TiCl4 as Lewis acid catalyst in anhydrous dichloromethane. The structure of cyclophane 2 was determined by single-crystal X-ray diffraction, and the impact of substrate concentration on the yield of macrocycle 2 was also examined. The study on the effect of substituents at the phenyl ring showed that the methoxy group in 1 is crucial for its trimerization to give the hexamethyl[3.3.3]metacyclophane derivative. Demethylation of 2 with BBr3 gave 1,1,10,10,19,19-hexamethyl-5,14,23-trihydroxy[3.3.3]metacyclophane (4) in 96% yield, and its three hydroxyl groups provide the possible modification sites for further construction of supramolecular assemblies. 相似文献
933.
Bei‐Bei Zhang Qian Jiang Zhi‐Xin Liao Chao Liu Shi‐Jun Liu 《Helvetica chimica acta》2013,96(7):1281-1289
Phytochemical investigation of the EtOH extract of Euphorbia sieboldiana led to the isolation of four new oleanane‐type triterpenoids, (1β,2α,3β,19β)‐1,2,3,19‐tetrahydroxyolean‐12‐en‐28‐oic acid, (1β,3β,19β)‐1,3,19‐trihydroxyolean‐12‐en‐28‐oic acid, (1β,2α,3β,16β,19β)‐1,2,3,16,19‐pentahydroxyolean‐12‐en‐28‐oic acid, and (1β,2α,3β,19β,23)‐1,2,3,19,23‐pentahydroxyolean‐12‐en‐28‐oic acid, along with 16 known compounds. Their structures were established by extensive 1D‐ and 2D‐NMR, as well as other spectral analyses. Biological evaluation of the four new triterpenoids revealed potent cytotoxic activities against HeLa and Hep‐G2 cells. 相似文献
934.
Hua‐Wei Li Sabyasachi Kar Pinghui Jiang 《International journal of quantum chemistry》2013,113(10):1493-1497
The effects of Debye plasma on the frequency‐dependent polarizabilities of Li and Na atoms are investigated using symplectic algorithm within the framework of the pseudostate summation technique. Dynamic dipole polarizabilities of Li (2s 2S) and Na(3s 2S) as functions of scaled number density of the plasma electrons for arbitrary plasma temperature are presented. Screening effects on the resonance frequencies are also presented. In free‐atomic cases, our calculated results are comparable with the reported theoretical and experimental predictions. © 2012 Wiley Periodicals, Inc. 相似文献
935.
The p‐π conjugation of tetra(naphthalene‐dione)porphyrins and tetra(naphthalene‐dithione)porphyrins is clarified on the basis of density functional theory studies. When carbonyl/thionyl is introduced, π bonds on the molecular skeleton become strong–weak alternated, and the conjugation transforms from “benzene‐type” to “butadiene‐type.” The unidirectional photon‐induced current associated with the p‐π conjugation enables the light‐harvesting efficiency of this kind of molecular skeleton reaches 90% in the range of 300–800 nm. Therefore, these compounds are ideal alternative for panchromatic dye‐sensitized solar cells. © 2013 Wiley Periodicals, Inc. 相似文献
936.
Qiong Wu Hui Feng Dong‐Dong Guo Mian‐Shuai Yi Xing‐Han Wang Bo Jiang Shu‐Jiang Tu 《Journal of heterocyclic chemistry》2013,50(3):599-602
A green and highly efficient method for the synthesis of polyfunctionalized indoline‐spiro fused pyran derivatives has been established. This reaction was conducted by reacting readily available and inexpensive starting materials, such as isatins, cyclic‐1,3‐dicarbonyl compounds, and malononitrile in aqueous media without any catalysts under microwave irradiation. The present green synthesis shows fascinating properties such as the use of water as the reaction solution, concise one‐pot conditions, short reaction periods (8–14 min), and easy purifications. The synthesis could also set a good example to GAP (Group‐Assistant‐Purification) chemistry in which purification via chromatography can be avoided and the pure products can be easily acquired only by washing the crude products with 95% EtOH. 相似文献
937.
A new and efficient access to (Z)‐N‐(2‐argio‐1‐(1H‐perimidin‐2‐yl)vinyl)benzamide derivatives from readily available substrates in HOAc is described with aid of microwave irradiation. The results of our study provide a simple, straightforward synthetic route to these interesting classes of 2‐substituted perimidines analogs in excellent yields. 相似文献
938.
E. -J. Gao L. -L. Jiang D. Zhang W. Jiao T. -L. Liu Y. -J. Zhang G. -L. Wu J. Xu 《Journal of Structural Chemistry》2013,54(5):978-982
A novel coordination polymer constructed with [Co(3,3′-bpbc)(H2O)3]·H2O(I) (3,3′-bpbc = 2,2′-bipyridine-3,3′-dicarboxylic acid) is successfully synthesized at room temperature and characterized by elemental analysis and IR spectra. The crystal structure of the complex is determined by single crystal X-ray diffraction. The unit cell parameters for complex I are: a = 9.9606(11) Å, b = 9.2552(10) Å, c = 16.0258(17) Å, β = 96.731(0)°, V = 1467.2(3) Å3, Z = 4, space group P2(1)/n. In the crystal, the cobalt(II) ion adopts a hexa-coordinate environment, and the structure units aggregate together to give birth to infinite 1D chains. The 2D and 3D framework is constructed via intermolecular hydrogen bonds. 相似文献
939.
We have developed a simple and efficient method for dispersive liquid-liquid microextraction of 4-nitrophenol, 2-naphthol and bisphenol A in real water samples. It is making use of solidified floating organic droplets of 1-dodecanol which has low density and a proper melting point. The type and volume of extraction solvent and dispersive solvent, the effect of salts, pH value and extraction time were optimized and resulted in enrichment factors of 84 for 4-nitrophenol, 123 for 2-naphthol, and 97 for bisphenol A. The limits of detection by HPLC are 1.50, 0.10 and 1.02 ng · mL?1, respectively. Excellent linearity is observed in the concentration range from 10 to 800 ng · mL?1, with coefficients of correlation ranging from 0.9988 to 0.9999. The relative standard deviations (for n?=?5) are from 3.2 to 5.3 %, and relative recoveries for the three phenols in tap, river and spring water range from 85.0 to 105.0 %, 98.3 to 110.0 %, and 98.6 to 109.0 %, respectively. Figure
Chromatograms of river water blank (b) and spiked river water (a, 500 ng ? mL?1) analyzed with DLLME-SFO-HPLC. Peak identification: (1) p-nitrophenol; (2) 2-naphthol; (3) bisphenol A. Liquid-liquid microextraction method based on solidification of floating organic droplet (DLLME-SFO) has a high enrichment factor (84, 123and 97), acceptable relative recovery (85.0 %–110.0 %), good repeatability (5.27 %, 3.54 % and 3.16 %) and a wide linear range (10–800 ng · mL?1) for the determination of p-nitrophenol, 2-naphthol and bisphenol A. 相似文献
940.
An efficient asymmetric synthesis of (R)-benzylic amines in optical purity 36–90% had been achieved by alkylation of a chiral ketimine prepared from D-camphor and benzylamine. Diastereoselectivity in the alkylation is dependent on the alkyl halides. 相似文献