Isomerization of 1-alkenes using the Na2Fe(CO)4/CuCl and Na2Fe(CO)4/BrCH2CH2 Br reagent systems
摘要:
The reagent Na2Fe(CO)(4) prepared in situ in THF by the reduction of Fe(CO)(5) with sodium naphthalenide reacts with certain alkenes in the presence of CuCl to bring about isomerization of the alkenes. Thus the 1-alkenes (1-dodecene, 1-decene, safrole and allyl benzene) are isomerized to trans-2-alkenes, and beta-pinene is isomerized to alpha-pinene. Reactions involving BrCH2CH2Br in place of CuCl give similar results.
METHOD FOR SYNTHESIZING SODIUM 2,2,6,6-TETRAMETHYLPIPERIDIDES
申请人:KOBELCO ECO-SOLUTIONS CO.,LTD.
公开号:US20190359571A1
公开(公告)日:2019-11-28
There is a demand for the development of a technique according to which sodium 2,2,6,6-tetramethylpiperidides (Na-TMPs) can be economically and efficiently synthesized through simple operations including a small number of steps under mild conditions in a short period of time. Also, there is a demand for the development of a technique according to which high-quality Na-TMPs that do not contain lithium or lithium compounds such as Li-TMP can be synthesized. The method for synthesizing sodium 2,2,6,6-tetramethylpiperidides includes a step of obtaining sodium 2,2,6,6-tetramethylpiperidides by reacting, in a reaction solvent, 2,2,6,6-tetramethylpiperidines with a dispersion product obtained by dispersing sodium in a dispersion solvent or an organosodium compound having an aromatic ring obtained through a reaction with a dispersion product obtained by dispersing sodium in a dispersion solvent.
<i>Z</i>-Selective Alkene Isomerization by High-Spin Cobalt(II) Complexes
作者:Chi Chen、Thomas R. Dugan、William W. Brennessel、Daniel J. Weix、Patrick L. Holland
DOI:10.1021/ja408238n
日期:2014.1.22
rare, because the more stable E-isomers are typically formed. We show here that cobalt(II) catalysts supported by bulky β-diketiminateligands have the appropriate kinetic selectivity to catalyze the isomerization of some simple 1-alkenes specifically to the 2-alkene as the less stable Z-isomer. The catalysis proceeds via an "alkyl" mechanism, with a three-coordinate cobalt(II) alkyl complex as the
简单的末端烯烃异构化为具有 Z 立体化学的内部异构体的情况很少见,因为通常会形成更稳定的 E 异构体。我们在这里表明,由庞大的 β-二酮亚胺配体支撑的钴 (II) 催化剂具有适当的动力学选择性来催化一些简单的 1-烯烃的异构化,特别是作为稳定性较差的 Z-异构体的 2-烯烃。催化通过“烷基”机制进行,三配位钴 (II) 烷基配合物作为静止状态。如同位素标记实验所示,β-氢化物消除和 [1,2]-插入步骤都很快。立体模型通过在 β-氢化物消除的过渡态钴 (II) 处的方形平面几何结构来解释选择性。该催化剂不仅适用于简单的烯烃,还适用于高烯丙基硅烷、缩酮、和甲硅烷基醚。从与不良底物的反应中分离出钴 (I) 或钴 (II) 产物表明,关键的催化剂分解途径是双分子的,降低催化剂浓度通常会提高选择性。除了潜在有用的选择性转化之外,这些研究还为高自旋钴配合物催化烯烃异构化提供了机理理解,并证明了空间体
Nonredox Metal-Ion-Accelerated Olefin Isomerization by Palladium(II) Catalysts: Density Functional Theory (DFT) Calculations Supporting the Experimental Data
作者:Ahmed M. Senan、Shuhao Qin、Sicheng Zhang、Chenling Lou、Zhuqi Chen、Rong-Zhen Liao、Guochuan Yin
DOI:10.1021/acscatal.6b01061
日期:2016.7.1
Redox metal-ion-catalyzed olefin isomerization represents one of the important chemical processes. This work illustrates that nonredox metal ions can sharply accelerate Pd(II)-catalyzed olefin isomerization, while Pd(II) alone is very sluggish. Nuclear magnetic resonance (NMR) and ultraviolet–visible light (UV-vis) characterizations disclosed that the acceleration effect originates from the formation
homogeneous catalysts. In contrast, very limited progress has been made with the use of cheap, Earth‐abundant base metals as heterogeneous catalysts for these transformations—in spite of the obvious economic and environmental advantages. Herein, we report on the use of an easily prepared heterogeneous catalyst material for the migration of olefins, in particular, for allylarenes. The catalyst material
Highly <i>Z</i>-Selective Double Bond Transposition in Simple Alkenes and Allylarenes through a Spin-Accelerated Allyl Mechanism
作者:Daniel Kim、Guy Pillon、Daniel J. DiPrimio、Patrick L. Holland
DOI:10.1021/jacs.1c00856
日期:2021.3.3
Double-bond transposition in alkenes (isomerization) offers opportunities for the synthesis of bioactive molecules, but requires high selectivity to avoid mixtures of products. Generation of Z-alkenes, which are present in many natural products and pharmaceuticals, is particularly challenging because it is usually less thermodynamically favorable than generation of the E isomers. We report a β-dialdiminate-supported