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21.
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Firouz Matloubi Moghaddam Zohreh Mirjafary Marjan Jebeli Javan Sara Motamen Hamid Saeidian 《Tetrahedron letters》2014
A mild and efficient tandem process for the synthesis of new highly substituted 2-pyrones starting from commercially available 2-arylacetic acids has been developed. The synthesis is based on the Knoevenagel condensation of 1,3-cyclohexadiones with various β-formyl-esters, followed by lactonization in the presence of nano ZnO (20 mol %). Moderate to high yields and readily available cheap starting materials are the key features of the present method. 相似文献
23.
Razieh Fazaeli Hamid Aliyan Elham Naderi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):745-754
Abstract The immobilization of heteropoly acids (HPAs) into the Al-functionalized KIT-6 mesoporous molecular sieve has been carried out to see the effect of Al-KIT-6 as a host matrix on the HPA activities. These modified mesoporous molecular sieves are effective catalysts for the Hosomi–Sakurai three-component coupling reaction via condensation of aldehydes, silyl ethers, and allylsilanes. Supplemental materials are available for this paper. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
24.
In this paper, using the Brzdek's fixed point theorem [9,Theorem 1] in non-Archimedean(2,β)-Banach spaces, we prove some stability and hyperstability results for an p-th root functional equation ■where p∈{1, …, 5}, a_1,…, a_k are fixed nonzero reals when p ∈ {1,3,5} and are fixed positive reals when p ∈{2,4}. 相似文献
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26.
The obtained results by soft modeling multivariate curve resolution methods often are not unique and are questionable because of rotational ambiguity. It means a range of feasible solutions equally fit experimental data and fulfill the constraints. Regarding to chemometric literature, a survey of useful constraints for the reduction of the rotational ambiguity is a big challenge for chemometrician. It is worth to study the effects of applying constraints on the reduction of rotational ambiguity, since it can help us to choose the useful constraints in order to impose in multivariate curve resolution methods for analyzing data sets. In this work, we have investigated the effect of equality constraint on decreasing of the rotational ambiguity. For calculation of all feasible solutions corresponding with known spectrum, a novel systematic grid search method based on Species-based Particle Swarm Optimization is proposed in a three-component system. 相似文献
27.
Hamid Reza Shaterian Asghar Hosseinian Majid Ghashang Fahimeh Khorami Neda Karimpoor 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):2333-2338
An environmentally friendly procedure for the preparation of dihydropyrimidinone derivatives or their sulfur analogues under thermal solvent-free conditions in the presence of aluminium hydrogen sulfate [Al(HSO4)3] and alumina sulfuric acid (Al2O3-SO3H) as heterogeneous catalysts was developed. 相似文献
28.
Mohammad Javad Taghizadeh Hamid ArvinnezhadSaadi Samadi Khosrow Jadidi Abdollah JavidanBehrouz Notash 《Tetrahedron letters》2012,53(38):5148-5150
An efficient, one-pot, three-component procedure for the synthesis of a small library of new chiral spirooxindolopyrrolizidines with high regio-, diastereo-, and enantioselectivity, from the 1,3-dipolar cycloaddition of azomethine ylides and optically active cinnamoyl oxazolidinone is described. The process occurs at room temperature in aqueous ethanol as a green solvent and in the absence of any Lewis acids. The oxazolidinone chiral auxiliary is removed in a non-destructive manner. The reaction mechanism is discussed on the basis of the assignment of the absolute configuration of the cycloadducts, and on theoretical calculations. 相似文献
29.
Zeinab Noroozi Tisseh Minoo Dabiri Mohsen Nobahar Hamid Reza Khavasi Ayoob Bazgir 《Tetrahedron》2012,68(6):1769-1773
An approach for the synthesis of new 5-substituted-tetrazoles via multi-component domino Knoevenagel condensation/1,3 dipolar cycloaddition reaction of carbonyl compounds, malononitrile and sodium azide in water without assistance of any catalyst has been reported. This general protocol provides a wide variety of 5-substituted 1H-tetrazoles in good yields under mild reaction conditions. 相似文献
30.
The viability and a number of morphological properties of in situ astrocytes of rat spinal cord cultures including changes in surface area and migration of both cell body and nucleus were investigated at magnetic field intensities comparable to those currently used for magnetic resonance imaging. Viability of rat spinal astrocytes was studied after up to 72 hours of 2.1T static magnetic field exposure. Surface areas and two-dimensional centroids of both soma and nucleus after 2 hours of magnetic field exposure were determined and compared with those of the same cells before magnetic field exposure. Cell membrane ruffling was quantified using fractal analysis. 相似文献