提出了使用一氧化碳作为直接还原剂将末端环氧化物和内部环氧化物脱氧成相应的烯烃。该反应由羰基钳-铱(I)络合物与路易斯酸助催化剂结合均匀催化,实现环氧化物底物的预活化,以及从γ-2-铱丁内酯中消除CO 2中间的。特别是末端烷基环氧化物在CO气氛下、苯或甲苯中、80-120℃下反应顺利,并且不会明显异构化为内烯烃。详细的研究揭示了环氧化物C−O键活化机制中底物依赖性变化,该变化发生在保留构型的氧化加成和导致构型反转的S N 2 反应之间。
A unique C–H allylation has been discovered with unbiased aliphatic olefins. An intimate M–L affiliation between a high-valent cobalt catalyst and amino-quinoline derived benzamides has been found to be crucial for this unprecedented selectivity. An exemplary set of aliphatic olefins, high yields coupled with excellent regio- and stereoselectivity, and wide functional group tolerances are noteworthy
<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
Site-Selective Catalytic Carboxylation of Unsaturated Hydrocarbons with CO<sub>2</sub> and Water
作者:Morgane Gaydou、Toni Moragas、Francisco Juliá-Hernández、Ruben Martin
DOI:10.1021/jacs.7b07637
日期:2017.9.6
A catalytic protocol that reliably predicts and controls the site-selective incorporation of CO2 to a wide range of unsaturatedhydrocarbons utilizing water as formal hydride source is described. This platform unlocks an opportunity to catalytically repurpose three abundant, orthogonal feedstocks under mild conditions.
描述了一种催化协议,该协议利用水作为正式氢化物源可靠地预测和控制 CO2 的位点选择性掺入到各种不饱和烃中。该平台为在温和条件下催化重新利用三种丰富的正交原料提供了机会。
A FACILE TRANSFORMATION OF ESTER GROUPS TO VINYL GROUPS BY THE ELECTROREDUCTIVE METHOD
A facile method of the transformation of esters to vinyl compounds was developed by using the electroreductive 1,2-elimination as a key step. β-Hydroxysulfones were electrochemically reduced to vinyl compounds in good yields. Hydroxyolefins could be also prepared from the corresponding lactones.
Pd-Catalyzed Highly Chemo- and Regioselective Hydrocarboxylation of Terminal Alkyl Olefins with Formic Acid
作者:Wenlong Ren、Jianxiao Chu、Fei Sun、Yian Shi
DOI:10.1021/acs.orglett.9b02101
日期:2019.8.2
An efficient Pd-catalyzed hydrocarboxylation of alkenes with HCOOH is described. A wide variety of linear carboxylic acids bearing various functional groups can be obtained with excellent chemo- and regioselectivities under mild reaction conditions. The reaction process is operationally simple and requires no handling of toxic CO.