烯烃的催化胺化是构建具有氮中心的复杂杂环最有吸引力的反应之一。在这里,我们提出协同光氧化还原和钴肟催化允许在没有外部氧化剂的情况下,各种 NH 亲核试剂与二、三和四取代烯烃之间进行高效和温和的脱氢反应,从而能够获得一系列N杂环。值得注意的是,含Z和E烯烃的N杂环都是可以得到的。机理研究表明Z-肉桂基衍生物可以通过光催化E to Z通过能量转移过程进行烯烃异构化。此外,我们发现缓慢的能量转移可以抑制E到Z烯烃异构化过程,从而提供具有E选择性的肉桂基衍生物。我们的结果突出了使用双光氧化还原和钴肟催化反应产生多种N-杂环的好处。
Formal Aza‐Wacker Cyclization by Tandem Electrochemical Oxidation and Copper Catalysis
作者:Xiangli Yi、Xile Hu
DOI:10.1002/anie.201814509
日期:2019.3.26
In oxidative electrochemical organic synthesis, radical intermediates are often oxidized to cations on the way to final product formation. Herein, we describe an approach to transform electrochemically generated organic radical intermediates into neutral products by reaction with a metalcatalyst. This approach combines electrochemical oxidation with Cu catalysis to effect formal aza‐Wacker cyclization
Brønsted Base Assisted Photoredox Catalysis: Proton Coupled Electron Transfer for Remote C−C Bond Formation via Amidyl Radicals
作者:Jiaqi Jia、Yee Ann Ho、Raoul F. Bülow、Magnus Rueping
DOI:10.1002/chem.201802907
日期:2018.9.20
The synthesis of alkyne‐ and alkene‐decorated lactams has been achieved through a photoredox‐initiated radical cascade reaction. The developed Brønsted base assisted, photoredox‐catalyzed, intramolecular 5‐exo‐trig cyclization/intermolecular radical addition/elimination reaction provides facile access to functionalized γ‐lactams, with good functional group tolerance and high yields.
Direct C–H/N–H dehydrogenative coupling is a promising yet thermodynamically unfavorable transformation in the absence of a sacrificial hydrogen acceptor. Herein, a conceptually novel oxidant-free dehydrogenative amination of alkenes through a synergistic photoredox and cobaltcatalysis with H2 evolution has been achieved. With this approach, a wide range of five-membered N-heterocycles were synthesized