Stereo- and Enantioselective Benzylic C–H Alkenylation via Photoredox/Nickel Dual Catalysis
作者:Xiaokai Cheng、Tongtong Li、Yuting Liu、Zhan Lu
DOI:10.1021/acscatal.1c02851
日期:2021.9.3
molecules undergo this cross-coupling reaction smoothly to afford chiral allylic compounds in up to 93% ee and >20/1 E/Z ratio under mild reaction conditions with good functional group tolerance. A triplet-energy-transfer-inhibiting strategy is developed for the stereoselective synthesis of alkenes under visible-lightphotocatalysis. The coordination pattern of nickel with chiral bis-imidazoline ligand has
报道了通过光氧化还原/镍催化的立体和对映选择性苄基 C-H 烯基化。容易获得的烷基苯和烯基溴化物,包括复杂的分子,在温和的反应条件下顺利地进行这种交叉偶联反应,以提供高达 93% ee 和 >20/1 E / Z比的手性烯丙基化合物,具有良好的官能团耐受性。开发了一种三重态能量转移抑制策略,用于在可见光光催化下立体选择性合成烯烃。基于非线性效应实验和 X 射线衍射,阐明了镍与手性双咪唑啉配体的配位模式。
New General Method for Regio- and Stereoselective Allylic Substitution with Aryl and Alkenyl Coppers Derived from Grignard Reagents
作者:Yohei Kiyotsuka、Yuji Katayama、Hukum P. Acharya、Tomonori Hyodo、Yuichi Kobayashi
DOI:10.1021/jo802426g
日期:2009.3.6
Allylic substitution with sp2-carbon reagents (aryl and alkenyl anions) was realized by usingallylic picolinates and copper reagents derived from RMgBr and CuBr·Me2S to afford anti SN2′ products regio- and stereoselectively. Steric and electronic factors in the reagents and the size of the methylene substituents around the allylic moiety marginally affected the selectivity. The reaction system was
通过使用烯丙基吡啶甲酸酯和衍生自RMgBr和CuBr·Me 2 S的铜试剂实现Sp 2-碳试剂(芳基和烯基阴离子)的烯丙基取代,可以在区域和立体选择性地提供抗S N 2'产物。试剂中的立体和电子因素以及烯丙基部分周围的亚甲基取代基的大小在一定程度上影响了选择性。该反应系统也与烷基试剂相容。此外,该取代被应用于四元中心的构建和(-)-倍半茶烯酚的合成。吸电子的C的吡啶基的性质和螯合(═ ö)-C 5 H ^ 4 Ñ到MgBr 2 发现原位产生的碳负责替代的高效率。
Picolinoxy Group, a New Leaving Group for anti S<sub>N</sub>2′ Selective Allylic Substitution with Aryl Anions Based on Grignard Reagents
作者:Yohei Kiyotsuka、Hukum P. Acharya、Yuji Katayama、Tomonori Hyodo、Yuichi Kobayashi
DOI:10.1021/ol800300x
日期:2008.5.1
The picolinoxy group was found to be an extremely powerful leavinggroup for allylic substitution with aryl nucleophiles derived from ArMgBr and CuBr*Me2S. The substitution proceeds with anti SN2' pathway and with high chirality transfer. The electron-withdrawing effect of the pyridyl group and chelation to MgBr2 are likely the origin of success. Results suggesting these effects were obtained.
Enantiospecific, Regioselective Cross-Coupling Reactions of Secondary Allylic Boronic Esters
作者:Laetitia Chausset-Boissarie、Kazem Ghozati、Emily LaBine、Jack L.-Y. Chen、Varinder K. Aggarwal、Cathleen M. Crudden
DOI:10.1002/chem.201303683
日期:2013.12.23
enantioselective Suzuki–Miyaura cross‐coupling of chiral, enantioenriched secondaryallylic boronic esters is described (see scheme; DME=dimethoxyethane, Bpin = pinacolboryl, dba = dibenzylideneacetone). Mechanistic studies show that the reactions proceed via γ‐selective transmetalation followed by reductive elimination. The reaction provides the first independent confirmation that the transmetalation of
Enantioselective Reductive
<scp>Cross‐Coupling</scp>
of Aryl/Alkenyl Bromides with Benzylic Chlorides
<i>via</i>
Photoredox/Biimidazoline Nickel Dual Catalysis
作者:Tongtong Li、Xiaokai Cheng、Jiamin Lu、Huifeng Wang、Qun Fang、Zhan Lu
DOI:10.1002/cjoc.202100819
日期:2022.5
The asymmetric reductive arylation and alkenylation of benzylic chloride under photoredox/nickel dual catalysis using chiral biimidazoline (BiIm) ligand is reported to access 1,1-diaryl alkanes and aryl allylic compounds with good yield as well as stereo- and enantioselectivities. This protocol uses more commercially available and less expensive C(sp2)-Br as the electrophile coupling partner. A primary