Nonproductive Events in Ring-Closing Metathesis Using Ruthenium Catalysts
作者:Ian C. Stewart、Benjamin K. Keitz、Kevin M. Kuhn、Renee M. Thomas、Robert H. Grubbs
DOI:10.1021/ja1029045
日期:2010.6.30
and nonproductive metathesis reactions of diethyl diallylmalonate are compared for eight different ruthenium-based catalysts. Nonproductive cross metathesis is proposed to involve a chain-carrying ruthenium methylidene. A second more-challenging substrate (dimethyl allylmethylallylmalonate) that forms a trisubstituted olefin product is used to further delineate the effect of catalyst structure on the
A highly enantioselective nickel-catalyzed intramolecular hydroalkenylation of N- or O-tethered 1,6-dienes was developed by using monodentate chiral spiro phosphoramidite ligands. The reaction provides an efficient and straightforward method for preparing very useful six-membered N- and O-heterocycles with high regioselectivity as well as excellent stereoselectivity from easily accessible starting
通过使用单齿手性螺亚磷酰胺配体开发了高度对映选择性镍催化的 N 或 O 系链 1,6-二烯的分子内加氢烯基化。该反应提供了一种有效且直接的方法,可以在温和的反应条件下从易于获得的起始材料中制备非常有用的六元 N-和 O-杂环,具有高区域选择性和优异的立体选择性。本研究中开发的手性螺镍催化剂是为数不多的用于非共轭二烯高度对映选择性环化的催化剂之一。
An efficient synthesis of 2-vinylic cyclic 1,3-alkadienes via the Cp*Ru(ii)-catalyzed intermolecular coupling reactions of alkynes and cyclic allenes
2-Vinylic cyclic 1,3-alkadienes can be obtained with moderate to good yields via the Cp*RuCl(PPh3)2-catalyzed coupling reaction of alkynes with cyclic allenes.
cleavage and the C–C bond formation of the transition state (TS) were observed in the Claisen rearrangement through the secondary kineticisotope effect, demonstrating the high detection sensitivity and accuracy of this method. More interestingly, this sm-KIE can be used to determine TS structures under different electric fields, revealing the multidimensional regulation of the TS. The detection and manipulation
通过使用石墨烯-分子-石墨烯单分子结,应用精确的单分子动力学同位素效应(sm-KIE)来规避传统整体 KIE 的固有限制。原位以高时间分辨率实时监测单分子反应轨迹具有表征KIE带来的更深层次信息的能力。通过二次动力学同位素效应在克莱森重排中观察到C-O键断裂和过渡态(TS)的C-C键形成,证明了该方法的高检测灵敏度和准确性。更有趣的是,这种 sm-KIE 可用于确定不同电场下的 TS 结构,揭示 TS 的多维调控。TS 的检测和操作为理解和优化化学反应和仿生进展提供了广阔的视角。
Copper‐Catalysed Synthesis of Propargyl Alcohol and Derivatives from Acetylene and other Terminal Alkynes
作者:Nikolai A. Sitte、Francesca Ghiringhelli、Grigory A. Shevchenko、Frank Rominger、A. Stephen K. Hashmi、Thomas Schaub
DOI:10.1002/adsc.202200369
日期:2022.7.5
reported. Using acetylene at atmospheric pressure, the catalyst consisting of <1 mol% copper(I) phenylacetylide and a trialkyl bisphosphine ligand shows a high selectivity towards the formation of propargylalcohol rather than 1,4-butynediol, which is not reported for common heterogeneous copper acetylide catalysts. The biphasic water/toluene reaction mixture allows the separation of targeted products with