Cyclopropanation of Terminal Alkenes through Sequential Atom‐Transfer Radical Addition/1,3‐Elimination
作者:Nicholas D. C. Tappin、Weronika Michalska、Simon Rohrbach、Philippe Renaud
DOI:10.1002/anie.201907962
日期:2019.10
An operationally simple method to affect an atom-transfer radical addition of commercially available ICH2 Bpin to terminal alkenes has been developed. The intermediate iodide can be transformed in a one-pot process into the corresponding cyclopropane upon treatment with a fluoride source. This method is highly selective for the cyclopropanation of unactivated terminal alkenes over non-terminal alkenes
A Structure–Activity Study of Ni-Catalyzed Alkyl–Alkyl Kumada Coupling. Improved Catalysts for Coupling of Secondary Alkyl Halides
作者:Peng Ren、Oleg Vechorkin、Kim von Allmen、Rosario Scopelliti、Xile Hu
DOI:10.1021/ja200270k
日期:2011.5.11
of several well-defined Ni catalysts that are significantly more active and efficient than the pincercomplex [((Me)N(2)N)NiCl] for the coupling of secondary alkyl halides. The best two catalysts are [((H)NN)Ni(PPh(3))Cl] and [((H)NN)Ni(2,4-lutidine)Cl]. The improved activity and efficiency was attributed to the fact that phosphine and lutidine ligands in these complexes can dissociate from the Ni
对 Ni 催化的烷基-烷基熊田型交叉偶联反应进行了结构-活性研究。合成了一系列新的镍(II)配合物,包括具有三齿钳状双(氨基)酰胺配体((R)N(2)N)和具有双齿混合氨基-酰胺配体((R)NN)的配合物并对其进行了结构表征. 这些配合物的配位几何形状从方形平面、四面体到方形金字塔形。该配合物已被研究作为未活化的烷基卤化物,特别是仲烷基碘化物与烷基格氏试剂交叉偶联的预催化剂。与先前报道的 Ni 钳形复合物 [((Me)N(2)N)NiCl] 获得的结果进行了比较。预催化剂中的金属转移位点对于催化是必需的。预催化剂的配位几何形状和自旋状态影响很小或没有影响。这项工作导致发现了几种明确定义的 Ni 催化剂,这些催化剂比钳形复合物 [((Me)N(2)N)NiCl] 更活跃、更有效,用于偶联仲烷基卤化物。最好的两种催化剂是 [((H)NN)Ni(PPh(3))Cl] 和 [((H)NN)Ni(2
Co-Catalyzed Cross-Coupling of Alkyl Halides with Tertiary Alkyl Grignard Reagents Using a 1,3-Butadiene Additive
作者:Takanori Iwasaki、Hiroaki Takagawa、Surya P. Singh、Hitoshi Kuniyasu、Nobuaki Kambe
DOI:10.1021/ja404285b
日期:2013.7.3
cobalt-catalyzed cross-coupling of alkyl (pseudo)halides with alkylGrignardreagents in the presence of 1,3-butadiene as a ligand precursor and LiI is described. Sterically congested quaternary carbon centers could be constructed by using tertiary alkylGrignardreagents. This reaction proceeds via an ionic mechanism with inversion of stereochemistry at the reacting site of the alkylhalide and is compatible with
cross-coupling reaction of alkyl halides with alkyl Grignard reagents by the combined use of cyclopentadienyl ligand and 1,3-butadiene additive is described. The reaction smoothly proceeds at room temperature using unactivated alkyl bromides and fluorides via non-radical mechanism, which is in sharp contrast with hitherto known Fe-catalyzed cross-coupling reactions of alkyl halides.
描述了通过组合使用环戊二烯基配体和 1,3-丁二烯添加剂,烷基卤化物与烷基格氏试剂的铁催化交叉偶联反应。该反应在室温下使用未活化的烷基溴和氟化物通过非自由基机制顺利进行,这与迄今为止已知的 Fe 催化烷基卤化物的交叉偶联反应形成鲜明对比。
Cross-coupling of alkyl halides with Grignard reagents using nickel and palladium complexes bearing η<sup>3</sup>-allyl ligand as catalysts
The cross-coupling of Grignard reagents with alkyl bromides and tosylates has been achieved by the use of eta(3)-allylnickel and eta(3)-allylpalladium complexes as catalysts.