[6π] photocyclization to cis-hexahydrocarbazol-4-ones: substrate modification, mechanism, and scope
Upon irradiation at λ = 366 nm, tertiary N-alkoxycarbonyl-N-aryl-β-enaminones furnished exclusively the trans-hexahydrocarbazol-4-ones by a conrotatory [6π] photocyclization but epimerized on silica to cis-hexahydrocarbazol-4-ones (14 examples, 44-98% yield). The acceptor substitution on the nitroge...
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| Hauptverfasser: | , |
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| Dokumenttyp: | Article (Journal) |
| Sprache: | Englisch |
| Veröffentlicht: |
January 16, 2019
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| In: |
The journal of organic chemistry
Year: 2019, Jahrgang: 84, Heft: 3, Pages: 1139-1153 |
| ISSN: | 1520-6904 |
| DOI: | 10.1021/acs.joc.8b03144 |
| Online-Zugang: | Verlag, Volltext: https://doi.org/10.1021/acs.joc.8b03144 Verlag: https://pubs.acs.org/doi/10.1021/acs.joc.8b03144 
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| Verfasserangaben: | Sachin G. Modha, Alexander Pöthig, Andreas Dreuw, and Thorsten Bach |
| Zusammenfassung: | Upon irradiation at λ = 366 nm, tertiary N-alkoxycarbonyl-N-aryl-β-enaminones furnished exclusively the trans-hexahydrocarbazol-4-ones by a conrotatory [6π] photocyclization but epimerized on silica to cis-hexahydrocarbazol-4-ones (14 examples, 44-98% yield). The acceptor substitution on the nitrogen atom enhanced the stability of the cyclized products compared to N-alkyl-N-aryl-β-enaminones reported previously. The mechanism of the [6π] photocyclization was investigated by quenching experiments, deuterium-labeling experiments, and DFT calculations, suggesting a triplet pathway for the conrotatory ring closure followed by a suprafacial [1,4] hydrogen migration. |
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| Beschreibung: | Im Text wird pi als griechischer Buchstabe dargestellt Gesehen am 20.11.2019 |
| Beschreibung: | Online Resource |
| ISSN: | 1520-6904 |
| DOI: | 10.1021/acs.joc.8b03144 |