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41.
Yimin Hu Prof. Dr. Yuan Qu Fenghua Wu Jinghan Gui Yun Wei Qiong Hu Shaowu Wang Prof. Dr. 《化学:亚洲杂志》2010,5(2):309-314
An efficient domino cyclization method for the construction of aza‐podophyllotoxin/aza‐conidendrin derivatives has been established. Reactions of different dienes with aryl halides in the presence of a palladium catalytic system produced different kinds of podophyllotoxin derivatives through a highly regioselective C? H functionalization. Treatment of dienes with aryl halides that have electron‐withdrawing substituents on the phenyl ring created aza‐podophyllotoxin derivatives by means of the functionalization of the C? H bonds ortho to the C? halide bonds of the incoming aryl halides. The reaction of dienes with 1‐iodobenzene or aryl halides that incorporate electron‐donating groups produced aza‐conidendrin derivatives by means of the functionalization of both sp3 C? H and sp2 C? H bonds. The regioselective C? H functionalization for the formation of different pseudo‐podophyllotoxin/‐conidendrin derivatives is proven by analyses of the 1H NMR spectra of the products and selective X‐ray analyses of the structures of the products. Thus, the palladium‐catalyzed domino cyclization of 1,6‐dienes for the preparation of aza‐podophyllotoxin/aza‐conidendrin derivatives can be controlled by selectively controlling the C? H functionalization. 相似文献
42.
Shaowu Zha 《Journal of solid state chemistry》2005,178(6):1844-1850
Complex metal oxides with composition of La0.75Sr0.25Cr1−xMnxO3(x=0.4,0.5,0.6) (LSCM) have been synthesized and examined as anode materials for solid oxide fuel cells (SOFCs). LSCM compositions show excellent tolerance to both reduction and oxidation but the crystal structure transforms from hexagonal in air to orthorhombic in H2. The volume change associated with this phase transformation is only about 1%, thus having little effect on other properties. The total electrical conductivity increases with the content of Mn, whereas the resistance to sulfur poisoning increases with the content of Cr. Fuel cells using LSCM as the anode show very good performance when pure hydrogen is used as the fuel. However, they do not appear to be stable in fuels containing 10% of H2S. 相似文献
43.
Reaction of [MoOS(3)](2)(-) and [WS(4)](2)(-) with Cudtp (dtp = diethyl dithiophosphate) gave rise to the clusters [Bu(4)N](2)[(MoOS(3))(4)Cu(12)(dtp)(6)], 1, and [Et(4)N][(WS(4)Cu(4))(dtp)(3)], 2, respectively. In cluster 1, the dtp- ligands act as both monodentate and bidentate ligands that bridge between Cu atoms and link together a closed double-cubane-like [Mo(2)O(2)S(6)Cu(6)](2+) core and two incomplete cubane-like [MoOS(3)Cu(3)]+ units. In cluster 2, the [WS(4)Cu(4)](2+) fragments were connected via bidentate and doubly bridging dtp- bridges to give a chain polymeric anion. Cluster 1 is the first example of a Mo/Cu/S cluster that contains a closed double-cubane-like structure. Compound 2 is also rare and the first W/Cu/S polymer with dtp- linkages. 相似文献
44.
本文报导了MoCl2(n-C8H17O)2-(i-Bu)2AlOph体系催化丁二烯聚合动力学研究结果,得到聚合速率方程式R=k(C)O(2)[M]=kpa(c)o(M),表观活化能18.6千卡/摩尔,指数前因子1.6×1010分-1,以及不同温度下的催化剂利用率,活性中心浓度,活性中心平均寿命等,还证明了等聚合速率的聚合时间tO与活性中心平均寿命相近。 相似文献
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Meihua Xie Xiaoxia Gu Jialiang Wang Jinhua Zhang Gaofeng Lin Shaowu Wang 《应用有机金属化学》2009,23(7):258-266
Tri‐ or tetrasubstituted alkenes with various substituents can be constructed regio‐ and stereospecifically by treatment of acetylenic sulfones with organozinc reagents in tetrahydrofuran followed by hydrolysis or coupling with halohydrocarbon. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
49.
Let F and F_1 be fields with |F| > 5, and n, n_1 integers satisfying $n\geq n_1$. The present paper determines the forms of homomorphisms from SP_{2n}(F) to SP_{2n}(F_1) and that from PSP_{2n}(F) to PSP{2n}(F_l). 相似文献