Dimethylzinc‐Initiated Radical Coupling of β‐Bromostyrenes with Ethers and Amines
作者:Amanda Sølvhøj、Andreas Ahlburg、Robert Madsen
DOI:10.1002/chem.201502429
日期:2015.11.2
A new coupling reaction has been developed in which β‐bromostyrenes react with ethers and tertiary amines to introduce the styryl group in the α‐position. The transformation is mediated by Me2Zn/O2 with 10 % MnCl2 and is believed to proceed by a radical addition–elimination mechanism. The ether and the amine are employed as solvent and the coupling takes place through the most stable α radical for unsymmetrical
已开发出一种新的偶联反应,其中β-溴苯乙烯与醚和叔胺反应,在α-位引入苯乙烯基。该转变是由具有10%MnCl 2的Me 2 Zn / O 2介导的,并且据认为是通过自由基加成-消除机理进行的。醚和胺用作溶剂,偶合通过非对称底物的最稳定的α基团发生。获得的产物为纯E异构体,产率中等至良好。可以使用一系列较小的环状和非环状醚/胺以及各种取代的β-溴苯乙烯实现偶联。
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
A novel approach of cycloaddition of difluorocarbene to α,β-unsaturated aldehydes and ketones: synthesis of gem-difluorocyclopropyl ketones and 2-fluorofurans
作者:Wei Xu、Qing-Yun Chen
DOI:10.1039/b212232d
日期:2003.3.27
acetals and ketals are easily obtained in moderate yields from the [1 + 2] cycloaddition of difluorocarbene to 1,3-dioxolanes of alpha,beta-unsaturated aromatic aldehydes and ketones. Hydrolysis of these fluorinated compounds under acidic conditions either gives the corresponding gem-difluorocyclopropyl ketones or 1-aryl-2-fluorofuran derivatives through intramolecular carbonium rearrangement with simultaneous
the structure of the isocyanide. The use of an electron-deficient aryl isocyanide, such as 2c and 2d, is required to selectively obtain the monoinsertion product. When aryl isocyanides containing alkyl substituents, such as 2a and 2b, are employed, two molecules of the isocyanide are incorporated, and the double-insertion product is obtained. The reaction of tert-octyl isocyanide also induces a double
描述了布朗斯台德酸催化异氰化物正式插入缩醛的 CO 键。各种非环状和环状缩醛可以应用于催化插入以形成 α-烷氧基亚胺酸酯。官能团,例如硝基、氰基、卤素、酯和烷氧基,可以耐受所采用的反应条件。反应过程高度依赖于异氰化物的结构。需要使用缺电子的芳基异氰化物,例如 2c 和 2d,以选择性地获得单插入产物。当使用含有烷基取代基的芳基异氰化物,例如2a和2b时,引入两个分子的异氰化物,得到双插入产物。叔辛基异氰化物的反应也诱导了双重掺入,但随后的酸介导的断裂会导致 2-烷氧基亚胺酰氰化物。单插入产物 α-烷氧基亚胺酸酯可以很容易地水解为 α-烷氧基酯,从而实现缩醛的正式羰基化。
The rapid photomediated alkenylation of 2-alkyl-1,3-dioxolanes with alkynes: a stereoelectronically assisted chain reaction
作者:Niall W. A. Geraghty、Andrea Lally
DOI:10.1039/b608979h
日期:——
The photomediated reaction of alkynes such as DMAD with 1,3-dioxolanes leads to remarkably rapid alkenylation; evidence is presented that these reactions occur via a chain mechanism.