Dinuclear Zinc Catalyzed Asymmetric Spirannulation Reaction: An Umpolung Strategy for Formation of α-Alkylated-α-Hydroxyoxindoles
作者:Barry M. Trost、Keiichi Hirano
DOI:10.1021/ol300577y
日期:2012.5.18
A highlydiastereo- and enantioselective formal [3 + 2] cycloaddition of α,β-unsaturated esters and 3-hydroxyoxindoles catalyzed by a dinuclear zinc-ProPhenol complex is reported. The stereoselective Michaeladditions of 3-hydroxyoxindoles and the subsequent transesterifications afford spirocyclic δ-lactones.
Lipophilic NHC catalysis in aqueous medium was reported for the synthesis of biologically relevant (a)symmetrically substituted and unsymmetrically substituted syncarpamide analogues. All the reported reactions were performed in the absence of any expensive metal salts or additives. A diverse array of syncarpamide analogues was obtained in good yields. Lipophilic NHC catalysis was also extended to
Synthesis and Characterization of <i>C</i>,<i>C</i>-Type Palladacycles and Their Catalytic Application in Mizoroki–Heck Coupling Reaction
作者:Chi Hou Lo、Hon Man Lee
DOI:10.1021/acs.organomet.8b00054
日期:2018.4.9
structures of three of the new complexes were further established by single-crystal X-ray diffraction studies. These complexes have been screened for catalyzing Mizoroki–Heck coupling reaction using ionic salt as solvent. The complex based on imidazo[1,2-a]pyridine, which has an electron-donating 4-methoxyphenyl ring on the ligand scaffold, was the most efficient catalyst, capable of using activated aryl chloride
以咪唑并[1,2- a ]吡啶和C2-苯基取代的咪唑部分为基础,开发并合成了两系列高配体前体,它们在咪唑环上具有N -CH 2(C═O)Ar取代基。与乙酸钯反应后,两个系列的配体在N -CH 2(C═O)Ar取代基的亚甲基和邻芳基碳位上都经历了双C–H键活化,生成C,C型带有五元螯合环的palladacycles。从具有溴化物阴离子的配体前体中获得具有桥联溴化物的二聚钯络合物,而与四氟硼酸根阴离子的前体形成具有两个“扔掉”吡啶配体的离子钯络合物。所有配合物都是空气稳定的,并通过1 H和13 C NMR光谱法和元素分析进行了表征。通过单晶X射线衍射研究进一步建立了三种新配合物的结构。这些配合物已经过筛选,可以使用离子盐作为溶剂催化Mizoroki-Heck偶联反应。基于咪唑并[1,2- a]的配合物在吡啶骨架上具有给电子4-甲氧基苯基环的对位吡啶是最有效的催化剂,能够使用活化的芳基氯化物和位