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An efficient chemoselective protocol is developed for the synthesis of (E)-cinnamic esters from substituted cinnamaldehydes or cinnamyl alcohols using a combination of DDQ and heterogeneous catalyst under microwave irradiation. The method showed remarkable selectivity for cinnamaldehydes over aliphatic and aromatic aldehydes, which is a novel finding. The results demonstrate that the developed protocol can be a useful synthetic tool for chemoselective esterification in total synthesis of complex organic compounds. 相似文献
84.
A series of fluorine-containing substituted spiro[piperidine-4,4′-pyrano[3,2-c]quinolines] were synthesized through a rapid one-pot multi-component reaction under microwave irradiation and sonication. The method has the advantages of excellent yields (80-96%) and short reaction time (3-10 min). We provide a series of fluorinated quinoline derivatives interesting for biological screening tests. 相似文献
85.
The classical Knoevenagel-Doebner reaction is reinvestigated wherein the direct synthesis of substituted 4-vinylphenols instead of the expected 4-hydroxycinnamic acids is described. The condensation reaction is performed on 4-hydroxy substituted benzaldehydes and malonic acid with a mixture of acetic acid-piperidine as condensing agent under focused microwave irradiation. The occurrence of simultaneous condensation-double decarboxylation without the use of any decarboxylating agent is a new finding, the reaction being facilitated solely by the hydroxy substituent and microwave irradiation effect. 相似文献
86.
Tengfei Gao Anuj Kumar Zhicheng Shang Xinxuan Duan Hangchao Wang Shiyuan Wang Shengfu Ji Dongpeng Yan Liang Luo Wen Liu Xiaoming Sun 《中国化学快报》1990,30(12):2274-2278
In CO2 electrochemical reduction, nanoporous SnOx-300 with high-level oxygen vacancies exhibited a partial current density of 15 mA/cm2 with the Faradaic efficiency (FE) of 88.6% for HCOOH production at 0.98 V versus RHE. 相似文献
87.
Assembly of New Heterocycles through an Effective Use of Bisaldehydes by Using a Sequential GBB/Ugi Reaction 下载免费PDF全文
A facile route for the assembly of new bis‐heterocyclic imidazo[2,1‐b][1,3]thiazinyl/benzothiazoyl‐phenyl)benzamide scaffolds through a two‐step Groebke–Blackburn–Bienaymé (GBB)/Ugi reaction sequence is reported, which establishes multiple points of diversity in the final products. The highlights of this procedure are the survival of the aldehyde group following the GBB reaction without the need for additional protection/deprotection steps. Moreover, the reaction is operationally simple, with the absence of any catalyst, and exhibits excellent functional‐group tolerance under minutes of microwave irradiation. 相似文献
88.
Dr. Vinay S. Sharma Dr. Anuj S. Sharma Suryajit L. Rathod Hitendra A. Mali Dr. Deepak Suthar Prof. Mahendra S. Dhaka Prof. Pranav S. Shrivastav 《Chemphyschem》2023,24(13):e202200760
The newly symmetrical liquid crystalline compounds (CPB1 – CPB4) based on calix[4]pyrrole as central rigid core are synthesized via esterification reaction. All the four functionalized compounds exhibit columnar hexagonal phase (Colh) over a higher mesophase temperature range and further stabilized mesophase upto room temperature. The thermal behavior and optical texture are identified by using differential scanning calorimetry (DSC), Polarizing optical microscopy (POM) while the molecular organization of compound in mesogenic state by X-ray diffraction technique. The molecular system based on calix[4]pyrrole core with symmetrical nature exhibited columnar type self-assembly at room temperature. All these four supramolecules with different side spacer show higher thermal stability. Based upon the optimization, compound CPB2 has been further tested to implicate as optical window layer in thin films solar cell devices. The calix[4]pyrrole functionalized supramolecular liquid crystalline compound based thin films showed suitable transmittance, optical energy band gap together with absorbance and extinction coefficient. The linear dependence of current on the voltage demonstrated Ohmic behavior of the CPB2 films. The surface morphology to the developed samples designated nearly uniform deposition of the CPB2 thin films together with grain growth. The findings warrant suitability of the films to implicate these as an eco-friendly optical window layer in thin films based solar cells. 相似文献
89.
An unprecedented route for the synthesis of N-1 substituted 5-(phenylsulfanyl)-1,4-dihydropyrazine-2,3-diones is disclosed starting from 5-chloro-3-(phenylsulfanyl)pyrazin-2(1H)-ones. The method comprises treatment of various 5-chloro-3-(phenylsulfanyl)pyrazin-2(1H)-ones with Na2CO3 in water under microwave irradiation providing the respective 5-(phenylsulfanyl)-1,4-dihydropyrazine-2,3-diones in good yields, via hydrolysis of the thioether bond and subsequent nucleophilic displacement of the chlorine by the in situ generated thiophenol. The obtained compounds are excellent precursors for the diversity oriented synthesis of pharmacologically active α,β-dicarbonyl compounds. 相似文献
90.
Mass transport across surfactant-covered oil-water interfaces of microemulsions plays an important role in numerous applications. In the current work, we use coarse-grained molecular dynamics simulations to investigate model systems containing flat hexadecane-water interfaces covered by monolayers of nonionic surfactants of various lengths. Several properties of the surfactant monolayers relevant to the mass transport are considered, including the monolayer microstructure, dynamics, and a free energy barrier to the solute transport. It is observed that the dominant contribution of a surfactant monolayer to the free energy barrier is a steric repulsion caused by a local density increase inside the monolayer. The local densities, and hence the free energy barriers, are larger for monolayers composed of longer surfactants. Since it is likely that the solute transport mechanism involves a sequence of jumps between short-lived pores within a monolayer, we perform a detailed analysis of structure, size, and lifetime of these pores. We demonstrate that the pore statistics is consistent with predictions of percolation theory and apply this theory to identify the characteristic length scale of the monolayer microstructure. The obtained pore structures are sensitive to minute changes of surfactant configurations occurring on the picosecond time scale. To reduce this sensitivity, the pores are averaged over short time intervals. The optimal duration of these time intervals is estimated from analysis of dynamics of pores with diameters comparable to or exceeding the characteristic percolation length scale. The developed approach allows one to filter out transient events of the pore dynamics and to focus on events leading to substantial changes of the monolayer microstructure. 相似文献