The conversion of ketones to esters has been achieved through the use of Cu catalyst and tetrabutylammonium nitrite. This reaction involves the activation of the less activated C-C bond, and the alkyl group is removed as a leaving group. Various isopropyl ketones are found to be good substrates for this reaction.
Mesoporous silica KIT-6 supported superparamagnetic CuFe<sub>2</sub>O<sub>4</sub> nanoparticles for catalytic asymmetric hydrosilylation of ketones in air
作者:Min Li、Bin Li、Hong-Feng Xia、Danru Ye、Jing Wu、Yifeng Shi
DOI:10.1039/c3gc42638f
日期:——
A diverse range of prochiral ketones were reduced in air with high yields and good-to-excellent enantioselectivities (up to 97% ee) in the presence of a heterogeneous catalyst system, which was in situ formed from catalytic amounts of superparamagnetic CuFe2O4 nanoparticles supported on mesoporous silica KIT-6 and non-racemic dipyridylphosphine ligand, the stoichiometric hydride donor polymethylhydrosiloxane
在非均相催化剂体系的存在下,在空气中以高收率和良好至优异的对映选择性(高达97%ee)还原了多种手性酮,该催化剂体系是由催化量的超顺磁性CuFe 2 O 4原位形成的介孔二氧化硅KIT-6和非外消旋二吡啶基膦配体,化学计量的氢化物供体聚甲基氢硅氧烷(PMHS)以及一定量的添加剂负载的纳米颗粒。磁性可分离的催化剂可以有效地重复使用4次,而活性和对映选择性均无明显损失。
Direct C–H Arylation of Aldehydes by Merging Photocatalyzed Hydrogen Atom Transfer with Palladium Catalysis
Herein, we report that merging palladium catalysis with hydrogen atom transfer (HAT) photocatalysis enabled direct arylations and alkenylations of aldehyde C–H bonds, facilitating visible light-catalyzed construction of a variety of ketones. Tetrabutylammonium decatungstate and anthraquinone were found to act as synergistic HAT photocatalysts. Density functional theory calculations suggested a Pd0–PdII–PdIII–PdI–Pd0
在本文中,我们报道了钯催化与氢原子转移(HAT)光催化的合并使醛C–H键的直接芳基化和烯基化成为可能,从而促进了可见光催化的各种酮的构建。发现四丁基癸酸铵和蒽醌可作为HAT的协同光催化剂。密度泛函理论计算表明,Pd 0 -Pd II -Pd III -Pd I -Pd 0途径,并揭示了在存在KHCO 3的情况下,Pd 0催化剂和光催化剂的再生同时发生。这种再生具有低能垒,促进了钯催化循环与光催化循环的有效耦合。本文报道的工作表明,HAT光催化在钯催化的交叉偶联和CH官能化反应中的进一步应用有望成功。
Light-Driven <i>N</i>-Heterocyclic Carbene Catalysis Using Alkylborates
a state-of-the-art methodology enabling radical–radical coupling. The catalytic process involves forming an acyl azolium intermediate from the NHC catalyst and an acyl donor, followed by single electron reduction of this key intermediate, which is largely dependent on the photoredox catalyst. We designed a radical NHC catalysis in which the direct photoexcitation of a borate to form a high reducing
Copper-dipyridylphosphine-catalyzed hydrosilylation: enantioselective synthesis of aryl- and heteroarylcycloalkyl alcohols
作者:Shan-Bin Qi、Min Li、Shijun Li、Ji-Ning Zhou、Jun-Wen Wu、Feng Yu、Xi-Chang Zhang、Albert S. C. Chan、Jing Wu
DOI:10.1039/c2ob27040d
日期:——
hydrosilylation of a vast array of aryl cycloalkyl ketones with different ring sizes was studied systematically for the first time (up to 99% enantiomeric excess). The results demonstrated that the steric size of cycloalkyl groups has a significant influence on the reaction outcomes. The first stereoselective formation of a selection of cyclohexyl heteroaryl alcohols of up to 97% enantiopurity was realized