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We herein report on solution structural studies of Ru^Ⅱ catalysts (3a, 9) composed of achiral bisphosphine ligands (4, 8) and the enantiopure 1,2-diphenylethylenediamine (DPEN). Complete chiral induction from enantiopure (R,R)-DPEN to achiral bisphosphine ligand 3a was observed in solution, with the complex adopting a single, stable and non-fluxional (even at 70 ℃) configuration. The coordination of the C=O moiety in 4 to the cationic Run center is considered to be of key importance in providing the higher thermodynamic and kinetic rotation barrier for the flexible bisphosphine ligand in the complex. The obtained enantioselectivity (91% enantiomeric excess) and sense of chiral induction in the hydrogenation of acetophenone were found to be solely dependent on the chirality of the 1,2-diamine. Consistent with the hydrogenation product, the (R,R)-DPEN induces a M-conformation (fight-handed) chirality for flexible phosphine ligand 4 in the complex, resulting in a 2,2-configuration about the Ru^Ⅱ center. 相似文献
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Introduction Optically active 1,1'-bi-2-naphthol (BINOL) and its derivatives have been widely used as chiral ligands of catalysts for asymmetric reactions and effective host compounds for the isolation or optical resolution of a wide range of organic guest molecules through the for-mation of crystalline inclusion complexes.1,2 The wide-ranging and important applications of these com-pounds in organic synthesis have stimulated great inter-est in developing efficient methods for their prepara-… 相似文献
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Two Co(Ⅱ) coordination polymers, namely [Co(L)Cl]_n(1) and [Co(L)(CH_3 COO)]_n(2), {HL = 3,5-di(4 H-1,2,4-triazole-4-yl)benzoic acid}, were synthesized under hydrothermal conditions. Compound 1 crystallizes in orthorhombic system, space group Pmma with a = 7.032(5), b = 11.555(8), c = 8.185(5) ?, V = 665.1(7) ?~3, Z = 2, Dc = 1.746 g/cm3~, F(000) = 350, Mr = 349.61, μ = 1.504 mm~(-1), the final R = 0.0568 and w R = 0.1739 for 2312 observed reflections with I 2σ(I). Compound 2 crystallizes in orthorhombic system, space group Pmma with a = 7.7505(17), b = 11.391(3), c = 8.0298(18) ?, V = 708.9(3) ?~3, Z = 2, Dc = 1.748 g/cm~3, F(000) = 378, Mr = 373.20, μ = 1.245 mm-1, the final R = 0.0350 and w R = 0.0873 for 5239 observed reflections with I 2σ(I). Single-crystal X-ray analyses revealed that complexes 1 and 2 exhibit similar 2 D layer structures with uncoordinated carboxyl as dangling arms. The neighboring layers are further connected by these arms, leading to interest 2 D → 3 D polythreading frameworks. Moreover, the magnetic susceptibility study indicates compound 1 exhibits antiferromagnetic behavior. 相似文献
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Under given conditions, two complexes of [Ni(H20)2BEDA]·2H2O 1 and [Ni(Py)2- BEDA]·6H2O 2 (BEDA = bis(3-methoxy-2-pyridyl)ether-6,6′-dicarboxylic acid) have been synthesized and characterized by elemental analysis and X-ray single-crystal diffraction. Crystal data for 1: C14H18NiN2O11, monoelinic C2/c, a = 14.3844(17), b = 12.9900(15), c = 9.6309(11) A, β = 104.3350(10)°, V= 1743.5(4) A3, Z = 4, Dc= 1.711 g/cm^3, F(000) = 928, μ = 1.179 mm^-1, Mr= 449.01, the final R = 0.0228 and wR = 0.0625. Crystal data for 2: C24H32NiN4O13, triclinic P1, a = 9.423(2), b = 11.863(3), c = 13.089(3) A, α = 91.511(3), β = 92.465(3), γ = 100.696(2)°, V = 1435.6(6) A^3, Z = 2, Dc= 1.488 g/cm^3, F(000) = 672, μ = 0.748 mm^-1, Mr= 643.25, the final R = 0.0400 and wR = 0.0975. Interestingly, in the two complexes, lattice water molecules dominate its crystal structures. Therefore, extensive intermolecular hydrogen bonds assemble 1 and 2 into 2D extended sheets and a 3D open framework, respectively. Furthermore, water molecules present in 2 are associated to form water clusters. 相似文献
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傅-克反应是有机化学中最基本的反应之一,但是对于催化的不对称傅-克反应的研究则处于起步阶段。最近这方面的研究获得了突破,本文简要介绍了催化不对称傅-克反应的最新动态,包括各种手性Lewis酸催化体系的开发及其在不对称合成中的应用。 相似文献
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1 INTRODUCTIONIntheprocessofthepreparationofNi(Pic) 2 L(L =1 ,3 bis (2 formylphenoxy) 2 hydroxyl propanethiosemicarbazone )mixedcomplexwithphen,aredcrystalwasobtainedinacetonitrilesolution .However,theelementalanalysisresultsoftheredcrystalindicatedthatitisnotthe… 相似文献
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催化不对称反应新发展: 不对称活化 总被引:8,自引:1,他引:7
介绍了催化不对称催化反应中的一个新概念-不对称活化(asymmetricactivation)及其研究的最新发展。运用不对称活化策略,一个光学活性的整或者甚至外消旋的催化剂可以被另一种手性活化剂(chiralactivator)选择性的活化,从而催化反应生成非外消旋产物。该方法较不对称活化(asymmetricactivation)方法的优点是被活化的催化剂能够产生较使用光学纯催化剂更高对映体过量的产物。 相似文献