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351.
A one-pot three-component synthesis of 6-aryl-8H-dibenzo[d,h][1,3,7,2]dioxazaborecin-8-ones is described. A mixture of 2-aminobenzoic acid, 2-hydroxybenzaldehyde, and arylboronic acid undergo a 1:1:1 addition reaction in CCl4 under microwave irradiation to produce bridgehead bicyclo[4.4.0]boron heterocycles in excellent yields. 相似文献
352.
Mehdi Adib Ehsan Sheikhi Mehdi Bagheri Hamid Reza Bijanzadeh Masoud Amanlou 《Tetrahedron》2012,68(15):3237-3242
A concise and facile synthesis of a new class of P,O-heterocycles is described. Knoevenagel condensation reaction of a salicylaldehyde and a cyclohexane-1,3-dione forms an α,β-unsaturated intermediate, which undergoes nucleophilic addition of a trialkyl phosphite under solvent-free conditions to afford the title compounds in good to excellent yields. 相似文献
353.
Triphenylphosphine ditriflate (TPPD) was found to be an efficient promoter for the Friedel-Crafts benzylation of arenes with benzyl alcohols in CH2Cl2 at room temperature. The good yields, the 1:1 molar ratio of arene and benzyl alcohol, the benzylation of chlorobenzene as a nonactivated aromatic compound at room temperature, and no by-product formation are the main advantages of this procedure. 相似文献
354.
A simple, efficient one-step route to polystyrene-supported trialkylphosphine ligands is reported. These polymer-supported alkyl phosphine ligands proved to be highly active for Suzuki-Miyaura reactions and in alkoxycarbonylation reactions. The palladium loaded polymer-supported catalysts can be recycled several times with only minimal loss of catalyst activity. 相似文献
355.
Ab initio molecular orbital calculations have been used to investigate the thermal decomposition kinetics of 2-chloroethylethyldichlorosilane at the B3LYP/6-311+G**,B3PW91/6-311+G**,and MPW1PW91/6-311+G** levels of theory.Among these methods,the results(activation parameters) obtained using the B3LYP/6-311+G** level are in good agreement with the available experimental data.The calculated data imply that in the unimolecular β-elimination reactions of the studied compound in the gas phase,the polarization of C(1)-Cl(3) and C(1)-H(4) bonds in the sense of C(1)δ+-Cl(3)δ-and C(1)δ+-H(4)δ-,respectively,is a determining factor in the gas phase elimination reactions 1,2 and 3.Analysis of bond order,natural bond orbital charges,bond indexes,synchro-nicity parameters,and IRC calculations suggest the elimination of 2-chloroethylethyldichlorosilane via reactions 1~3 can be described as concerted and slightly asynchronous.The transition state structures of these reactions are a four-membered cyclic structure. 相似文献
356.
Afshin Amini Babak Amini Ehsan Momtahan Mohammad Hassan Shirdareh Haghighi 《Acta Mathematica Hungarica》2012,134(3):369-384
We associate a graph Γ+(R) to a ring R whose vertices are nonzero proper right ideals of R and two vertices I and J are adjacent if I+J=R. Then we try to translate properties of this graph into algebraic properties of R and vice versa. For example, we characterize rings R for which Γ+(R) respectively is connected, complete, planar, complemented or a forest. Also we find the dominating number of Γ+(R). 相似文献
357.
Theoretical study of exohedral chemical functionalization of C48B6N6 with NH3 molecules has been investigated using DFT. It was found that NH3 molecule can be chemically adsorbed on boron sites of C48B6N6, with a charge transfer from NH3 to C48B6N6. Adsorption energy and the quantity of electron charge transfer from latest adsorbed ammonia to C48B6N6 decreased with increasing in the adsorbed NH3 molecules. Despite the strong adsorption energies, electronic properties of C48B6N6 is preserved after modification(s) with NH3 molecule(s) and chemical modification of C48B6N6 with NH3 molecules can be viewed as some kind of safe modification. 相似文献
358.
Ehsan Zahedi 《Physica B: Condensed Matter》2012,407(23):4503-4511
The nonequilibrium Green's function approach in combination with density-functional theory is used to perform quantum mechanical calculations of the electron transport properties of furan and thiophene dimmers. Both the molecular systems have two S-linker and translated into the Gold junction with (1 1 1) surfaces. The studied molecular junctions at zero bias voltage are HOMO-based junctions and currents through these systems are driven by hole transport. The current–voltage characteristics of the both studied molecular junctions illustrate that negative differential resistance (NDR) feature is observed over the bias voltage of 2.0 V. Higher conductivity of fused furan dimmer and NDR character have been explained by the monitoring of the transmission resonance peak across the bias window against varying bias voltages. 相似文献
359.
This article deals with constructing a confidence interval for the reliability parameter using ranked set sampling. Some asymptotic and resampling-based intervals are suggested, and compared with their simple random sampling counterparts using Monte Carlo simulations. Finally, the methods are applied on a real data set in the context of agriculture. 相似文献
360.
Seyed Mohammad Sadegh Modarres Mosadegh Ehsan Movahednia 《Journal of Fixed Point Theory and Applications》2018,20(1):34
The aim of this paper is to investigate Hyers–Ulam–Rassias stability of preserving lattice functional equation in various spaces. First, we prove stability of generalized preserving lattice functional equation in Banach lattices. Next, we show stability of preserving lattice cubic functional equation in Menger probabilistic normed Riesz spaces. 相似文献