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181.
Uddin SJ Shilpi JA Middleton M Byres M Shoeb M Nahar L Sarker SD 《Natural product research》2007,21(7):663-668
The reversed-phase HPLC analysis of a methanol extract of the aerial parts of Cuscuta reflexa afforded a non-separable mixture (55 : 45) of two novel tetrahydrofuran derivatives, named swarnalin (1) and cis-swarnalin (2), and a known coumarin, 5,6,7-trimethoxycoumarin (3). The structures of the compounds were elucidated unequivocally by UV, HRFABMS and a series of 1D and 2D NMR analyses. The mixture of 1 and 2 showed significant free radical scavenging activity in the DPPH assay and the RC50 value was found to be 3.80 x 10(-4) mg mL(-1) for the mixture, compared to 2.88 x 10(-5) mg mL(-1) for the positive control, quercetin. 相似文献
182.
A selective, reductive, deoxygenation of 2-aryl-4-hydroxycyclopent-2-en-1-ones to afford 2-aryl-cyclopent-2-en-1-ones was achieved by NaBH4–CeCl3 in methanol. 相似文献
183.
Santosh A. Jadhav Mahesh G. Shioorkar Omprakash S. Chavan Aniket P. Sarkate Devanand B. Shinde 《合成通讯》2017,47(4):285-290
An effective, expeditious, environmentally benign one-pot synthesis of 2-phenylimidazo[1,2-a]pyridines and 2-phenylimidazo[1,2-a]quinoline from easily available starting materials as aromatic carbonyl compound, 2-amino pyridine, succinamide, and in situ generated α-iodo acetophenone in combination with green solvent PEG-400 and water (2:1) under microwave irradiation. The newly developed protocol with excellent yield of product in very short time of reaction by avoiding the use of lachrymatric α-chloro and α-bromocarbonyl compounds, volatile, toxic organic and hazardous solvents, reagents is the advantage of this research work. The final products were confirmed by their characterization data such as 1H NMR, 13C NMR, high resolution mass spectrometry (HRMS) and were compared with its reported method. 相似文献
184.
Here we report a novel Baker yeast catalyzed one pot cyclocondensation, performed at room temperature in ethanol for obtaining high yields of polyfunctionalized pyridines, 2-amino-4-aryl-3,5-dicyano-6-phenylthiopyridines. The developed protocol obeys certain green principles and is scalable and cost effective. 相似文献
185.
R. R. Chavan V. Raghavendra 《International Journal of Mathematical Education in Science & Technology》2013,44(5):735-739
In this paper, an attempt is made to construct a mathematical model to present a picture of a biological system, namely the evolutionary status of secondary phloem in dicotyledonous plants. In this study 16 parameters have been taken into account. The biological nature of each parameter leads to a mathematical relation and this relationship is exploited to compute a number (conveniently made to lie between 0 and 100) which represents the advance feature of the plant. Thus, given two plants A and B, these computations show whether A is more advanced than B or not. In this communication a set of 18 plants are considered. 相似文献
186.
S. D. Chavan B. D. Watode P. G. Hudge D. B. Suryawanshi C. G. Akode A. C. Kumbharkhane S. C. Mehrotra 《Indian Journal of Physics》2010,84(4):419-429
Complex dielectric permittivity measurements in the frequency range 10MHz-20GHz have been carried out in diol-water mixtures
over the entire concentration range using a time domain reflectometry (TDR) method at 25°C. A hydrogen bonded theory is applied
to compute the dielectric constant for the mixtures. It adequately reproduces the experimental values of static dielectric
constants for the diol-water mixtures. The dielectric parameters confirm that the intermolecular homogeneous and heterogeneous
hydrogen bonding vary significantly with the increase in concentration of the constituents of the diol-water mixtures. 相似文献
187.
The thermogravimetric analysis of several coprecipitated zinc-copper oxalates in nitrogen is reported. The thermal decompositions of these mixed oxalates show a separate single step for dehydration and decomposition in the mass loss versus temperature curve. It is found that the onset temperature decreases with composition. For example, it decreases from 380 for zinc oxalate to 260 for copper oxalate. The end-product is mixed oxides and copper metal. These studies indicate the formation of an interpenetrating structure or mixed crystals during coprecipitation. Rate parameters have been calculated for dehydration and decomposition.One of us (B. D. D.) is grateful to the University Grants Commission, New Delhi, India, for the award of a research fellowship. 相似文献
188.
Zanamivir is the known potent anti-influenza agent targeting the key enzyme neuraminidase that cleaves sialic acid from cell
receptors allowing release of newly formed virions. Molecular dynamics simulation was carried out to determine the dynamic
behavior of Zanamivir upon its binding to flexible loops of neuraminidase and to analyse its interactions in the bioactive
state. Neuraminidase exhibits wide range of affinity with structurally similar compounds. CoMFA study was used to determine
quantitative structure-activity relationship for 36 carbocyclic Neuraminidase inhibitors (NIs). The CoMFA model was also successfully
built using cross-validated r2cv = 0.580{{r}^{2}_{\rm cv} =0.580} and r2pred=0.638{{r}^{2}_{\rm pred}=0.638} . 相似文献
189.
Bloch ED Murray LJ Queen WL Chavan S Maximoff SN Bigi JP Krishna R Peterson VK Grandjean F Long GJ Smit B Bordiga S Brown CM Long JR 《Journal of the American Chemical Society》2011,133(37):14814-14822
The air-free reaction between FeCl(2) and H(4)dobdc (dobdc(4-) = 2,5-dioxido-1,4-benzenedicarboxylate) in a mixture of N,N-dimethylformamide (DMF) and methanol affords Fe(2)(dobdc)·4DMF, a metal-organic framework adopting the MOF-74 (or CPO-27) structure type. The desolvated form of this material displays a Brunauer-Emmett-Teller (BET) surface area of 1360 m(2)/g and features a hexagonal array of one-dimensional channels lined with coordinatively unsaturated Fe(II) centers. Gas adsorption isotherms at 298 K indicate that Fe(2)(dobdc) binds O(2) preferentially over N(2), with an irreversible capacity of 9.3 wt %, corresponding to the adsorption of one O(2) molecule per two iron centers. Remarkably, at 211 K, O(2) uptake is fully reversible and the capacity increases to 18.2 wt %, corresponding to the adsorption of one O(2) molecule per iron center. Mo?ssbauer and infrared spectra are consistent with partial charge transfer from iron(II) to O(2) at low temperature and complete charge transfer to form iron(III) and O(2)(2-) at room temperature. The results of Rietveld analyses of powder neutron diffraction data (4 K) confirm this interpretation, revealing O(2) bound to iron in a symmetric side-on mode with d(O-O) = 1.25(1) ? at low temperature and in a slipped side-on mode with d(O-O) = 1.6(1) ? when oxidized at room temperature. Application of ideal adsorbed solution theory in simulating breakthrough curves shows Fe(2)(dobdc) to be a promising material for the separation of O(2) from air at temperatures well above those currently employed in industrial settings. 相似文献
190.
A stereoselective synthesis of (-)-1-epi-ventiloquinone L and (+)-ventiloquinone L, the monomeric unit of cardinalin 3 has been described. The synthesis is completed in 7 steps with 10.5% and 13% overall yields for (-)-1-epi-ventiloquinone L and (+)-ventiloquinone L respectively. The key steps involve D?tz benzannulation of carbene 5 with alkyne 6 to give a substituted naphthalene moiety and oxa-Pictet-Spengler reaction to install the 1,3-dimethylpyran moiety. 相似文献