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[(DPEPhos)(bcp)Cu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst
Published on: May 21, 2019
Pd(OAc)2-catalyzed regioselective aromatic C-H bond fluorination.
Shao-Jie Lou1, Dan-Qian Xu, Ai-Bao Xia
1Catalytic Hydrogenation Research Center, State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Zhejiang University of Technology, Hangzhou 310014, PR China.
Chemical Communications (Cambridge, England)
|June 6, 2013
Summary
A new palladium-catalyzed system enables selective ortho-monofluorination of N-heterocycles. This method utilizes a palladium(II/IV) catalytic cycle, offering a precise approach for synthesizing fluorinated organic compounds.
Area of Science:
- Organic Chemistry
- Catalysis
- Fluorination Chemistry
Background:
- Palladium-catalyzed C-H functionalization is a powerful tool in organic synthesis.
- Selective ortho-functionalization of N-heterocycles remains a synthetic challenge.
- Fluorinated organic compounds possess unique properties relevant to pharmaceuticals and materials science.
Purpose of the Study:
- To develop a novel catalytic system for highly selective ortho-monofluorination of N-heterocycles.
- To investigate the scope and limitations of the developed fluorination method.
- To elucidate the catalytic mechanism of the observed transformation.
Main Methods:
- Development of a novel palladium(II) acetate (Pd(OAc)2)-N-fluorobenzenesulfonimide (NFSI)-trifluoroacetic acid (TFA) catalytic system.
- Application of the system to various aryl-N-heterocyclic directing groups, including quinoxaline, pyrazole, benzo[d]oxazole, and pyrazine derivatives.
- Mechanistic studies using Electrospray Ionization-Tandem Mass Spectrometry (ESI-MS/MS) to propose a palladium(II/IV) catalytic cycle.
Main Results:
- Achieved highly selective ortho-monofluorination of diverse N-heterocyclic compounds.
- Demonstrated the broad applicability of the developed Pd(OAc)2-NFSI-TFA system.
- Proposed a plausible Pd(II/IV) catalytic cycle supported by ESI-MS/MS experimental evidence.
Conclusions:
- The novel Pd(OAc)2-NFSI-TFA system provides an efficient and selective method for ortho-monofluorination of N-heterocycles.
- The proposed Pd(II/IV) catalytic cycle offers insights into the mechanism of this selective fluorination reaction.
- This methodology expands the synthetic toolbox for accessing valuable fluorinated N-heterocyclic compounds.
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