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81.
A useful synthesis of 3-hydroxy-4-chromanone (6) is not currently available. Lead tetraacetate oxidation of 4-chromanone (4) yields the C(3) acetoxy derivative but this compound could not be deacetylated to 6.1 Recently Donnelly and Maloney reported2 that the Algar-Flynn-Oyamada reaction (H2O2/CH3OH/NaOH), which is commonly used for the conversion of o-hydroxychalcones (1) into 3-hydroxyflavanone (2) and 3-hydroxyflavones (3), does not yield 6 when applied to o-hydroxya-crylophenone 1 (R = H). The authors found that under less basic conditions using K2CO3 some 6 is formed but the major product is catechol. These observations clearly indicate the necessity of developing a method for making 6. The present note describes a staightforward way of preparing 3-hydroxy-4-chromanone (6) in good yield. 相似文献
82.
We have achieved a facile copper(II) bromide–catalyzed synthesis of 2,3,4-trisubtitued pyrrole incorporated into unsymmetrical triarylmethanes through direct replacement of hydroxyl group in the pyrrolyl phenyl methanol with electron-rich aromatic and heteroaromatic compounds. The newly developed method has been applied to a facile synthesis of a C2 symmetric bis-triarylmethane in which the two triarylmethanes were bridged through piperzine. The copper(II) bromide catalysis led to C-C bond formation at the C(5) position when the reacting partner was imidazole. In contrast, C-N bond formation took place with benzimdazole or 2-methylbenzimidazole. 相似文献
83.
Manne Annapurna P. Vishnuvardhan ReddySurya Prakash Singh Mannepalli Lakshmi Kantam 《Tetrahedron》2013
The palladium-catalyzed cross-coupling reaction of vinyl heteroaromatic compounds with aryl bromides and heteroaryl bromides is described using air and moisture stable N,N′,N″,O-tetrafunctional Pd catalyst under phosphine-free conditions. As a result a variety of trans-1,2-disubstituted vinyl heterocycles were obtained in high to good yields. 相似文献
84.
A simple and sensitive spectrophotometric method for the determination of hydrogen peroxide, based on the increase in color intensity of dye on addition of surfactant, is described. Hydrogen peroxide is first reacted with potassium iodide in acidic medium, in presence of ammonium molybdate to liberate iodine. The liberated iodine oxidizes leucocrystal violet to crystal violet having maximum absorbance at 593 nm. The color of the dye intensifies with the addition of the surfactant, cetyl pyridinium chloride though the absorption maximum remains the same. Beer's law is obeyed in the range 0.05–0.45 µg of hydrogen peroxide per 25 mL of final solution (0.002–0.018 µg mL?1) with an excellent correlation coefficient (r = 0.9977). The proposed method has been successfully applied for the analysis of hydrogen peroxide in various food products and rainwater. 相似文献
85.
Ashish Goyal J.B. Shukla A.K. Misra Ajai Shukla 《Mathematical Methods in the Applied Sciences》2015,38(17):4300-4316
People having extreme idealogies affect the process in a region using fear of terror acts, money power, and the word of mouth communication network to change individuals to their way of thinking. This forces government to divert its limited financial resources for controlling extremism and thus affecting development. In this paper, therefore, a nonlinear mathematical model is proposed to study the dynamics of extremism governed by four dependent variables, namely, number of people in the general population having no extreme ideology, number of extreme ideologists, number of isolated ideologists (prisoners), and the cumulative density of government efforts and their interactions. The model is analyzed using the stability theory of differential equations and computer simulation. The analysis shows that if appropriate level of government efforts is applied on extremists, the spread of their ideology can be controlled in the general population. A numerical study of the model is also carried out to investigate the effects of certain parameters on the spread of extremism confirming the analytical results.Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
86.
Khadhar Navaz Umar Basha Shanthi Gnanamani Prakash Shanmugam Sujatha Venugopal Sangeetha Murthy Balagurunathan Ramasamy 《Journal of heterocyclic chemistry》2021,58(10):2000-2008
A simple and convenient method for the one-pot synthesis of 3-(1H-indole-3-carbonyl)-2H-chromen-2-one derivatives from the reaction of 3-cyanoacetyl indole and salicylaldehyde in the presence of Na2CO3 in water: methanol (1:1) is described. Wider substrate scope, high yields, operational simplicity, and simple purification process make the protocol highly applicable in the synthesis of 3-(1H-indole-3-carbonyl)-2H-chromen-2-ones. For the first time, in vitro antioxidant and antimicrobial activity was studied. Compounds 5e , 7a , and 7b exhibits good radical scavenging ability against DPPH free radical. Compounds 7b , 5f , and 5g possess lower EC50 values than the Standards AA and BHA and thus proving their high reducing power. Compounds 5d and 5f show good antibacterial activity against gram-positive bacteria (MRSA) while compounds 5c , 7a , and 7b exhibits good antibacterial activity against Bacillus sp. Compounds 5b and 5e show good antibacterial activity against gram negative bacterial strains (Escherichia coli, Klebsiella pneumoniae) and compounds 5g and 5h exhibits good antifungal activity against Candida albicans. 相似文献
87.
Pandey Shwetank Shashi Barwa Manjeet Singh Gautam Yogendra Prakash Markandeya Pani Balaram 《Journal of Radioanalytical and Nuclear Chemistry》2021,329(1):35-43
Journal of Radioanalytical and Nuclear Chemistry - GIS based groundwater uranium and other physico-chemical parameters pH, electrical conductivity, oxidation reduction potential, temperature,... 相似文献
88.
Parajuli Prakash Acharya Sanjit Shamshina Julia L. Abidi Noureddine 《Cellulose (London, England)》2021,28(12):7559-7577
Cellulose - In this study, alkali and alkaline earth metal chlorides with different cationic radii (LiCl, NaCl, and KCl, MgCl2, and CaCl2) were used to gain insight into the behavior of cellulose... 相似文献
89.
90.