Zinc(ii) ortho-hydroxyphenylhydrazo-β-diketonate complexes and their catalytic ability towards diastereoselective nitroaldol (Henry) reaction
作者:Maximilian N. Kopylovich、Tatiana C. O. Mac Leod、Kamran T. Mahmudov、M. Fátima C. Guedes da Silva、Armando J. L. Pombeiro
DOI:10.1039/c0dt01457e
日期:——
The zinc(II) complexes with ortho-hydroxy substituted arylhydrazo-β-diketonates [Zn2(CH3OH)2(μ-L1)2] (5), [Zn(CH3)2SO}(H2O)(L2)] (6), [Zn2(H2O)2(μ-L3)2] (7) and [Zn(H2O)2(L4)]·H2O (8) were synthesized by reaction of a zinc(II) salt with the appropriate hydrazo-β-diketone, HO-2-C6H4-NHNCC(O)CH3}2 (H2L1, 1), HO-2-O2N-4-C6H3-NHNCC(O)CH3}2 (H2L2, 2), HO-2-C6H4-NHNCC(O)CH2C(CH3)2CH2C(O) (H2L3, 3) or HO-2-O2N-4-C6H3-NHNCC(O)CH2C(CH3)2CH2C(O) (H2L4, 4). They were fully characterized, namely by X-ray diffraction analysis that disclosed the formation of extensive H-bonds leading to 1D chains (5 and 6), 2D layers (7) or 3D networks (8). The thermodynamic parameters of the Zn(II) reaction with H2L2 in solution, as well as of the thermal decomposition of 1â8 were determined. Complexes 5â8 act as diastereoselective catalysts for the nitroaldol (Henry) reaction. The threo/erythro diastereoselectivity of the β-nitroalkanol products ranges from 8â:â1 to 1â:â10 with typical yields of 80â99%, depending on the catalyst and substrate used.
锌(II)复合物与邻羟基取代的芳基肼-β-二酮配体 [Zn2(CH3OH)2(μ-L1)2] (5)、[Zn(CH3)2SO}(H2O)(L2)] (6)、[Zn2(H2O)2(μ-L3)2] (7) 和 [Zn(H2O)2(L4)]·H2O (8) 是通过将锌(II)盐与相应的肼-β-二酮反应合成的,反应物分别为 HO-2-C6H4-NHNCC(O)CH3}2 (H2L1, 1)、HO-2-O2N-4-C6H3-NHNCC(O)CH3}2 (H2L2, 2)、HO-2-C6H4-NHNCC(O)CH2C(CH3)2CH2C(O) (H2L3, 3) 或 HO-2-O2N-4-C6H3-NHNCC(O)CH2C(CH3)2CH2C(O) (H2L4, 4)。这些复合物经过全面表征,特别是通过 X 射线衍射分析揭示了形成广泛的氢键,导致形成一维链(5 和 6)、二维层(7)或三维网络(8)。还确定了 Zn(II) 与 H2L2 溶液反应的热力学参数,以及 1–8 的热分解过程。复合物 5–8 作为二对旋选择性催化剂用于硝基醛(Henry)反应。β-硝基醇产物的 threo/erythro 立体选择性从 8:1 到 1:10不等,典型收率为 80–99%,具体取决于所用的催化剂和底物。