Metal-free access to β-carbolines via single-electron transfer catalyzed by a triaryl carbenium ion pair
The β-carboline moiety exists in a wide range of drugs and natural products, but synthesis often relies on noble metals and stochiometric oxidants. Here, we develop a metal-free strategy using a triaryl carbenium ion pair as a catalyst to access β-carbolines from tryptamines and aromatic aldehydes....
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| Main Authors: | , , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
2023
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| Subjects: | |
| Online Access: | https://hdl.handle.net/10356/168719 |
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| Institution: | Nanyang Technological University |
| Language: | English |
| Summary: | The β-carboline moiety exists in a wide range of drugs and natural products, but synthesis often relies on noble metals and stochiometric oxidants. Here, we develop a metal-free strategy using a triaryl carbenium ion pair as a catalyst to access β-carbolines from tryptamines and aromatic aldehydes. This protocol exhibits excellent functional group tolerance, and its practicality is demonstrated with the preparation of Eudistomin U and fluorescent compounds on gram scales. Mechanistic studies reveal that the trityl radical is generated via a single-electron transfer process and subsequently trapped by an oxygen molecule. In addition, the in-situ-generated reactive oxygen-centered radical is also found to be essential for the efficient dehydroaromatization process to afford the desired products. |
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