In Situ Preparation of a Highly Active N-Heterocyclic Carbene-Coordinated Olefin Metathesis Catalyst
作者:John P. Morgan、Robert H. Grubbs
DOI:10.1021/ol0063510
日期:2000.10.1
active N-heterocyclic carbene-coordinatedcatalysts may be synthesized and used in situ, without requiring prior isolation of the catalyst. Activation of this in situ catalyst with ethereal HCl dramatically reduces the reaction times required for high conversions. A variety of alpha,beta-unsaturated carbonyl-containing substrates participate readily in cross and ring-closing metathesis reactions using this
Catalytic Asymmetric Epoxidation of α-Branched Enals
作者:Olga Lifchits、Corinna M. Reisinger、Benjamin List
DOI:10.1021/ja1037935
日期:2010.8.4
An asymmetric catalytic epoxidation of alpha-branched, alpha,beta-unsaturated aldehydes is presented. A highly synergistic combination of a primary cinchona-based amine and a chiral phosphoric acid was found to promote the reaction with excellent enantiocontrol for alpha-monosubstituted and alpha,beta-disubstituted enals.
Ruthenium-Catalyzed Tandem Cross-Metathesis/Wittig Olefination: Generation of Conjugated Dienoic Esters from Terminal Olefins
作者:Ryan P. Murelli、Marc L. Snapper
DOI:10.1021/ol070445t
日期:2007.4.1
In the presence of ruthenium-based olefin metathesis catalysts and triphenylphosphine, alpha,beta-unsaturated aldehydes can be olefinated with diazoacetates. This ruthenium-catalyzed transformation has been employed in tandem with olefin cross-metathesis to convert terminal olefins into 1,3-dienoic esters in a single operation.
Formal Vinyl C���H Activation and Allylic Oxidation by Olefin Metathesis
A General Model for Selectivity in Olefin Cross Metathesis
作者:Arnab K. Chatterjee、Tae-Lim Choi、Daniel P. Sanders、Robert H. Grubbs
DOI:10.1021/ja0214882
日期:2003.9.1
When an olefin of high reactivity is reacted with an olefin of lower reactivity (sterically bulky, electron-deficient, etc.), selective cross metathesis can be achieved using feedstock stoichiometries as low as 1:1. By employing a metathesis catalyst with the appropriate activity, selective cross metathesis reactions can be achieved with a wide variety of electron-rich, electron-deficient, and sterically
近年来,烯烃交叉复分解(CM)已成为有机化学中一种强大而方便的合成技术;然而,作为一种通用的合成方法,CM 受到产品选择性和立体选择性缺乏可预测性的限制。对几类烯烃(包括取代和官能化的苯乙烯、仲烯丙醇、叔烯丙醇和具有 α-季铵盐中心的烯烃)进行烯烃交叉复分解的研究,得出了一个通用模型,可用于预测交叉反应中的产物选择性和立体选择性。复分解。作为 CM 中烯烃反应性的一般排名,烯烃可以根据它们通过交叉复分解进行均二聚化的相对能力和它们的同二聚体对二级复分解反应的敏感性进行分类。当高反应性烯烃与低反应性烯烃(空间体积大、缺电子等)反应时,可以使用低至 1:1 的原料化学计量实现选择性交叉复分解。通过使用具有适当活性的复分解催化剂,可以与多种富电子、缺电子和空间大的烯烃实现选择性交叉复分解反应。该模型的应用允许预测和开发选择性交叉复分解反应,最终形成前所未有的三组分分子间交叉复分解反应。通过使用具