Palladium-Catalyzed Allenamide Carbopalladation/Allylation with Active Methine Compounds
作者:Xiaoyi Zhu、Ruibo Li、Hequan Yao、Aijun Lin
DOI:10.1021/acs.orglett.1c01369
日期:2021.6.18
carbopalladation/allylation with active methine compounds has been developed. Various indoles and isoquinolinones bearing a quaternary carbon center were achieved with good efficiency, a broad substrate scope and good functional group tolerance. This reaction underwent cascade oxidative addition, carbopalladation, and allylicalkylation, and two new C–C bonds were formed in one pot.
Saegusa Oxidation of Enol Ethers at Extremely Low Pd-Catalyst Loadings under Ligand-free and Aqueous Conditions: Insight into the Pd(II)/Cu(II)-Catalyst System
作者:Quan Zhu、Yunsong Luo、Yongyan Guo、Yushun Zhang、Yunhai Tao
DOI:10.1021/acs.joc.0c02987
日期:2021.4.16
system of Saegusa oxidation, which converts enolethers to the corresponding enals with a number of diverse substrates at extremely low catalyst loadings (500 mol ppm) under ligand-free and aqueous conditions, is described. Its synthetic utility was demonstrated by large-scale applications of the catalyst system to important nature molecules. This work allows Saegusa oxidation to become a highly practical
The first nickel-catalyzed desymmetric hydrogenation has been achieved. With the Ni(OTf)2/(S,S)-Ph-BPE system, a series of γ,γ-disubstituted cyclohexadienones were transformed to the corresponding cyclohexenones with a chiral all-carbon quaternary center at the γ position in high yields (92% to 98%) and excellent enantioselectivities (92% to 99% ee). This catalytic system can also tolerate the desymmetric
首次实现了镍催化的不对称氢化。使用 Ni(OTf)2/(S,S)-Ph-BPE 系统,一系列 γ,γ-二取代环己二烯酮以高产率转化为相应的环己烯酮,其在 γ 位具有手性全碳四元中心( 92% 至 98%)和出色的对映选择性(92% 至 99% ee)。该催化体系还可以耐受螺碳环环己二烯酮的去对称反应,以产生相应的带有手性螺季碳的环己烯酮,收率高(94% 至 98%)和 ee 值(96% 至 99% ee)。此外,该方法为天然产物大麻吡酮 A 和 B 的中间体提供了一种高效、简洁的合成路线。
Rhodium-Catalyzed Desymmetric Arylation of <i>γ,γ</i>-Disubsituted Cyclohexadienones: Asymmetric Synthesis of Chiral All-Carbon Quaternary Centers
作者:Yu Qiao、Shiming Bai、Xiao-Feng Wu、Ying Yang、He Meng、Jialin Ming
DOI:10.1021/acs.orglett.2c00225
日期:2022.2.25
desymmetric arylation of prochiral cyclohexadienones with ArZnCl in the presence of an (R)-segphos–rhodium catalyst gave high yields of the corresponding cyclohexenones, which contain a chiral arylated carbon center at the β-position and a chiral all-carbon quaternary center at the γ-position, with high diastereo- and enantioselectivities. This catalytic system was also applied to the arylation of spirocarbocyclic
在 ( R )-segphos-铑催化剂存在下,前手性环己二烯酮与 ArZnCl 的不对称芳基化得到高产率的相应环己烯酮,其在β位含有手性芳基化碳中心,在γ-位,具有高非对映选择性和对映选择性。该催化体系还应用于螺碳环环己二烯酮的芳基化,并提供了相应的带有高 dr 和 ee 的手性螺季碳的环己烯酮。
Direct C–H Cyanation by ICN Formed <i>In Situ</i>: Nannozinone B
作者:Paul Wienecke、Hans-Dieter Arndt
DOI:10.1021/acs.orglett.3c00176
日期:2023.2.24
A novel method for C–H cyanation of different pyrans, pyrroles, indoles, and acyclic nucleophilic double bonds using TMSCN, NIS, and Zn(OTf)2 as a catalyst is described. The transformation is conducted under mild conditions tolerating a variety of functional groups. Zn(OTf)2 is likely to serve a dual catalytic role as an activator for TMSCN and for the cyanogen iodide generated in situ. Optimization