In this communication, a highly selective palladium-catalyzed carbonylative four components procedure for the transformation of allenes, alcohols and nitroarenes has been developed. The desired 2-aminomethyl substituted 3-arylacrylates were produced in good yields with Mo(CO)6 as the solid CO source. Furthermore, nitroarenes have been used as reaction partners and oxidant in this catalytic system.
Efficient Intramolecular Hydroalkoxylation of Unactivated Alkenols Mediated by Recyclable Lanthanide Triflate Ionic Liquids: Scope and Mechanism
作者:Alma Dzudza、Tobin J. Marks
DOI:10.1002/chem.200902269
日期:2010.3.15
catalytic pathway that involves kinetically significant intramolecular proton transfer. The present activation parameters—enthalpy (ΔH≠)=18.2 (9) kcal mol−1, entropy (ΔS≠)=−17.0 (1.4) eu, and energy (Ea)=18.2 (8) kcal mol−1—suggest a highly organized transition state. Proton scavenging and coordinative probing results suggest that the lanthanide triflates are not simply precursors of free triflic acid. Based
[Ln(OTf)3 ]类型的镧系三氟甲磺酸盐配合物(Ln = La,Sm,Nd,Yb,Lu)可作为有效的可循环催化剂,用于伯/仲和脂族/芳族化合物的快速分子内加氢烷氧基化(HO)/环化咪唑基室温离子液体(RTIL)中的羟基烯烃,生成相应的呋喃,吡喃,螺双环呋喃,螺双环呋喃/吡喃,苯并呋喃和异色满衍生物。产物直接从催化溶液中分离出来,转化表现出马尔可夫尼科夫区域选择性,周转频率高达47 h -1在120°C下。初级烯醇环化的环大小速率依赖性为5> 6,与空间控制的过渡态一致。末端烯醇的加氢烷氧基化/环化速率比内部烯醇的加氢烷氧基化/环化速率稍快,这表明在环状过渡态中适度的空间需求。芳基官能化羟基烯烃的环化速率比线性烯醇的环化速率更快,而五元和五元/六元螺双环骨架也被区域选择性封闭。在主要的空间受限的烯醇的环化过程中,从La 3+(1.160Å)到Lu 3+,对金属离子半径的周转频率依赖性降低了约80倍(0
New selectivities from old catalysts. Occlusion of Grubbs’ catalysts in PDMS to change their reactions
作者:M. Brett Runge、Martin T. Mwangi、Ned B. Bowden
DOI:10.1016/j.jorganchem.2006.09.022
日期:2006.12
dissolved in methylene chloride also react by olefin isomerization with occluded catalysts. Eleven examples of substrates that exhibit dual reactivity by undergoing olefin isomerization with occluded catalysts and olefin metathesis with catalysts dissolved in methylene chloride are reported. Most of these substrates have olefins with allylic phosphine oxides, carbonyls, or ethers. Control experiments demonstrate
Gold Redox Catalysis through Base‐Initiated Diazonium Decomposition toward Alkene, Alkyne, and Allene Activation
作者:Boliang Dong、Haihui Peng、Stephen E. Motika、Xiaodong Shi
DOI:10.1002/chem.201701970
日期:2017.8.16
The discovery of photoassisted diazonium activation toward gold(I) oxidation greatly extended the scope of goldredoxcatalysis by avoiding the use of a strongoxidant. Some practical issues that limit the application of this new type of chemistry are the relative low efficiency (long reaction time and low conversion) and the strict reaction condition control that is necessary (degassing and inert
通过避免使用强氧化剂,光辅助重氮盐向金(I)氧化活化的发现大大扩展了金氧化还原催化的范围。限制这种新型化学方法应用的一些实际问题是相对较低的效率(较长的反应时间和较低的转化率)和必须进行严格的反应条件控制(脱气和惰性反应环境)。在本文中,通过路易斯碱诱导的重氮活化已经开发出另一种无光条件。通过这种方法,将不活泼的Au I催化剂与Na 2 CO 3和重氮盐结合使用以生产Au III中间的。实现了对各种基质(包括炔烃,烯烃和丙二烯)的有效活化,然后快速进行了Au III还原消除,从而得到了具有良好收率或优异收率的C-C偶联产物。相对于以前报道的光活化方法,我们的方法通过更快的反应速率和更宽的反应范围提供了更高的效率和多功能性。在光引发条件下(<5%收率)不能活化的具有挑战性的底物,例如富电子/中性亚勒烯,可以被活化,随后以良好或优异的产率产生所需的偶联产物。
Automated Electrochemical Selenenylations
作者:Thomas Wirth、Nasser Amri
DOI:10.1055/s-0039-1690868
日期:2020.6
Integrated electrochemical reactors in automated flow systems were utilised for selenenylation reactions. The automation allowed multiple electrochemical reactions of a programmed sequence to be performed in a fully autonomous way. Many functionalised selenenylated products were synthesised in short reaction times in good to high yields.