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61.
A silver-catalyzed reaction of 2-alkynylbenzaldoxime with arylsulfonyl chloride proceeds smoothly at room temperature to afford 4-tosyloxyisoquinolines in moderate to good yields. Additionally, the resulting 4-tosyloxyisoquinolines could be further elaborated through palladium-catalyzed coupling reactions leading to diverse isoquinolines. 相似文献
62.
Graphene (G) supported Pd–Co bimetallic nanoparticles (NPs) as a highly active catalyst was prepared by a chemical reduction method and used for coupling reactions. With the characterization of X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and Raman spectrum, the composition of resulting Pd–Co material was identified to be alloy structural. The Pd–Co (1:1)/G exhibited the highest catalytic activity for the Sonogashira-type coupling reactions and also exerted satisfied catalytic activity and recycle stability for Suzuki–Miyaura cross-coupling reactions. This Pd–Co/G material also possessed other advantages such as low-cost, easy recycled from reaction system by a magnet for their magnetic property, and easy experimental handling. 相似文献
63.
In the course of our syntheses of functionalised pyridine and quinoline derivatives, we examined the reactivities of pyridine and quinoline N-oxides towards the nucleophilic addition of acidic carbon derivatives. Different activating reagents were used, such as PyBroP, triflic anhydride and a combination of pyrrolidine phosphoramide and triflic anhydride. 相似文献
64.
生物质醇/醛是一类重要的生物基平台化合物, 通过催化氧化重整可将其进一步转化为高值含氧化学品或燃料. 太阳能驱动的光电催化技术是实现生物质醇/醛氧化最为绿色高效的途径之一. 与传统光电解水制氢相比, 利用生物质醇/醛氧化来替代阳极析氧过程不仅可以提高阳极产物的附加值, 同时可以提升太阳能到氢能的转化效率. 因此, 光电解水制氢耦合生物质醇/醛氧化对绿氢提效降本和高值化学品合成具有重要意义. 本文综合评述了光电解水制氢耦合生物质醇/醛的氧化反应机理, 总结了目前光电催化技术在生物质醇/醛氧化方面的研究进展, 最后对该领域所面临的机遇和挑战进行了展望. 相似文献
65.
Three-arm and four-arm star-like polybutadienes(PBds) were synthesized via the combination of living anionic polymerization and the click coupling method. Kinetic study showed that the click reaction between the azido group terminated PBd-t-N3 and the alkyne-containing multifunctional linking reagent was fast and highly efficient. All coupling reactions were fully accomplished within 40 min at 50 °C in toluene in the presence of the reducing agent Cu(0), proven by 1H-NMR, FTIR and GPC measurements. For the coupling reactions between the PBd-t-N3 polymer and dialkyne-containing compound, the final conversion of the coupled PBd-PBd polymer was ca. 97.0%. When a PBd-t-N3 polymer was reacted with trialkyne-containing or tetraalkyne-containing compound, the conversion of three-arm or four-arm PBd was around 95.5% or 87.0%, respectively. Several factors influencing the coupling efficiency were studied, including the molecular weight of the initial PBd-t-N3, arm numbers and the molar ratio of the azido group to the alkynyl group. The results indicated that the conversion of the target products would be promoted when the molecular weight of the PBd-t-N3 was low and the molar ratio of the azido to alkynyl groups was close to 1. 相似文献
66.
迄今为止,贵金属(铑、钯、钌等)在过渡金属催化的碳碳键生成反应中发挥着主导作用,然而使用廉价金属催化剂更符合可持续发展的要求。锰是地壳中含量排第三位的过渡金属,价格便宜,环境危害性小,有潜力成为贵金属催化剂的替代品并发挥其自身独特的反应性。尽管锰参与的当量反应有大量文献报道,目前锰催化的反应尤其是碳碳键生成反应的发展还不成熟,如何实现高效的催化循环是锰催化领域面临的主要难题之一。本文对锰催化的付-克烷基化反应、格氏试剂的酰化反应、偶联反应、碳金属化反应、自由基反应和碳氢键活化反应进行了综述。 相似文献
67.
The coupling and radiation characteristics of an improved dielectric waveguide directional coupler with a tapering left-handed
slab core located in the coupling region are analyzed by the staircase approximation method, which combines the building block
approach and multi-mode network theory with a rigorous mode-matching procedure. Particular attentions are directed toward
the radiation characteristics under different structural parameters of the coupler. Numerical results indicate that the proposed
coupler is very promising by shortening the coupling length significantly while keeping the radiation loss at a low level. 相似文献
68.
利用基于亚波长衍射光栅理论的介质-金属-介质的对称夹层结构,对掺杂的双包层光纤进行多点泵浦,根据严格的电磁场衍射理论和光栅方程,分析了多点泵浦时,这种耦合结构的泵浦光泄露的问题,证明了多点泵浦时泵浦光的泄露率仅为15.52%,而对信号光则不存在泄露。这种对称夹层结构可以用于多个大功率激光二极管阵列的多点侧面泵浦双包层掺杂光纤中,以制作各种大功率(数kW级)稀土光纤激光器,其最大耦合效率可以达到80%以上。 相似文献
69.
70.