Triaryl carbonium ion-pair-mediated cooperative aerobic dehydrogenation of N-heterocycles
The triphenylmethyl radical was discovered by Gomberg in 1900 and has been shown to be a persistent radical species. Surprisingly, this radical is rarely used in organic synthesis since its discovery over a century ago. Here, we report a metal-free aerobic dehydrogenation of N-heterocycles mediated...
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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/10356/171494 |
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| Institution: | Nanyang Technological University |
| Language: | English |
| Summary: | The triphenylmethyl radical was discovered by Gomberg in 1900 and has been shown to be a persistent radical species. Surprisingly, this radical is rarely used in organic synthesis since its discovery over a century ago. Here, we report a metal-free aerobic dehydrogenation of N-heterocycles mediated by a triphenylmethyl radical generated from a triaryl carbonium ion pair as the precatalyst in the presence of TEMPO. This protocol exhibits a broad substrate scope and excellent functional group tolerance. The practicality has also been demonstrated with the gram-scale preparation of key intermediates of small-molecule drugs and late-stage functionalization of various dipine drugs. Mechanistic studies and DFT calculations revealed that the triphenylmethyl radical was involved in the catalytic cycle and was essential for the aerobic dehydrogenation process. |
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