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941.
Ju‐Hua Peng Run‐Hong Jia Ning Ma Ge Zhang Fei‐Yue Wu Chuang Cheng Shu‐Jiang Tu 《Journal of heterocyclic chemistry》2013,50(4):899-902
A series of furo[3,4‐b]indeno[2,1‐f]quinolin‐1‐one derivatives were synthesized by the condensation of an aromatic aldehyde with tetronic acid and 9H‐fluoren‐2‐amine in solvent of glacial acetic acid under microwave irradiation. This procedure offers several advantages including operational simplicity, clean reaction, and increased safety for small‐scale high‐speed synthesis. 相似文献
942.
Feng Shi Dianxiang Zhou Shujiang Tu Qingqing Shao Chunmei Li Longji Cao 《Journal of heterocyclic chemistry》2008,45(4):1065-1070
A series of furo[3,4‐b][4,7]phenanthroline and indeno[2,1‐b][4,7]phenanthroline derivatives were synthesized via a three‐component reaction of aromatic aldehydes, 6‐aminoquinoline and either tetronic acid or 1,3‐indanedione in water, under microwave irradiation without use of any catalyst. This green procedure offers several advantages including operational simplicity, clean reaction, and increased safety for small‐scale high‐speed synthesis. 相似文献
943.
944.
A series of planar chiral diphosphine-oxazoline ferrocenyl ligands with different electronic properties were successfully used in the asymmetric allylic substitutent reaction. The enantioselectivity of this reaction was affected by the electronic nature of the ligands. When the electronic effect was coincident with the steric effect of ligand, a higher ee value was observed. 相似文献
945.
[reaction: see text] A practical and efficient total synthesis of (+/-)-galanthamine was achieved from commercially available materials through a novel approach, in which the construction of its core structure and the special allylic alcohol group were based on a successive semipinacol rearrangement/desilyation/cyclization and Saegusa-Ito oxidation, respectively. 相似文献
946.
An attempt to utilize a new strategy for alkaloid synthesis which features the intramolecular [4+2] cycloaddition of enamines and enamides for the construction of the tetracyclic spiroamine skeleton characteristic of the Erythrina alkaloids was unsuccessful, unexpectedly giving a bridged cycloadduct rather than a fused one. 相似文献
947.
Let \[{\mathfrak{M}_k}\] denote the space of Lorentz witb. constant curvature:
\[1 + {K_{\eta pq}}{x^p}{x^q}\]
where K is a constant and \[\eta = ({\eta _{pq}})\]=diag [1,... 1,-1], We have considered the
wave equation with variable coefficients
\[\frac{\partial }{{\partial {x^j}}}(\sqrt {|\tilde g|} ){{\tilde g}^{jk}}\frac{{\partial u}}{{\partial {x^k}}}) = 0\]
in \[{\mathfrak{M}_k}\] where
\[|\tilde g| = |1 + {K_{\eta pq}}{x^p}{x^q}{|^{ - (n + 1)}},{{\tilde g}^{jk}} = (1 + {K_{\eta pq}}{x^p}{x^q})({\eta _{jk}} + K{x^j}{x^k})\]
and found the explicit solution of the Cauchy problem for equation (1) 相似文献
948.
Zhendong Yan Wei Du Linlin Tu Ping Gu Zhong Huang Peng Zhan Fanxin Liu Zhenlin Wang 《Journal of Raman spectroscopy : JRS》2015,46(9):795-801
Plasmonic systems based on metal nanoparticles on a metal film with high optical absorption have generated great interests for surface‐enhanced Raman scattering (SERS). In this study, we prepare a broadband‐visible light absorber consisting Au nanotriangles on the surface of a continuous optically opaque gold film separated with a dielectric SiO2 layer, which is a typical metal‐insulator‐metal (MIM) system, and demonstrate it as an efficient SERS substrate. The MIM nanostructure, prepared using nanosphere lithography with a very large area, shows a broadband with absorption exceeding 90% in the wavelength regime of 630–920 nm. We observe an average SERS enhancement factor (EF) as large as 4.9 × 106 with a 22‐fold increase compared to a single layer of Au nanotriangles directly on a quartz substrate. A maximum SERS EF can be achieved by optimizing the thicknesses of the dielectric layer to control the optical absorption. Owing to the simple, productive, and inexpensive fabrication technique, our MIM nanostructure could be a potential candidate for SERS applications. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
949.
Chen W Mbafor W Roberts SM Whittall J 《Journal of the American Chemical Society》2006,128(12):3922-3923
A very simple, highly stereoselective and modular synthesis of ferrocene-based P-chiral phosphine ligands has been developed. On the basis of this new methodology, several new families of ferrocene-based phosphine ligands have been prepared coupling chirality at phosphorus with other, more standard stereogenic features. The introduction of P-chirality into ferrocene-based phosphine ligands enhances the enantioselective discrimination produced by the corresponding Rh catalyst when a matching among the planar chirality, carbon chirality, and the chirality of phosphorus is achieved. 相似文献
950.
Yilmaz B Müller U Tijsebaert B De Vos D Xie B Xiao FS Gies H Zhang W Bao X Imai H Tatsumi T 《Chemical communications (Cambridge, England)》2011,47(6):1812-1814
A new zeolite catalyst, Al-RUB-41, was synthesized for the first time. It was tested as a catalyst in methanol amination, and showed a shape-selective performance that results in a highly favorable product distribution. The shape-selective nature was also evidenced by using Pt-Al-RUB-41 as a bifunctional catalyst for decane hydroconversion. With its unique pore architecture and remarkable shape-selective character, Al-RUB-41 presents a significant commercial potential in industrial catalysis. 相似文献