6,7‐Benzotropolone Syntheses Based on Ring‐Closing Metatheses and Four‐Electron Oxidations
Four homoallyl ortho‐vinylaryl ketones (10a‐ d) – 1,8‐dienes of sorts – were prepared by several approaches. In the presence of 1–2 mol‐% Grubbs‐II catalyst, they ring‐closed to give 6,7‐dihydrobenzocyclohepten‐5‐ones (11a‐ d) in 90–96 % yield. With SeO2 the parent compound (11a) delivered benzocyclohepten‐5‐one (13a) and/or selenium‐containing compounds (18–22) but no more than traces of 6,7‐benzotropolone (5a). However,5a was accessible from compound11a via the sodium enolate and allowing it to react with a stream of oxygen (43 % yield). The sodium enolates of the substituted 6,7‐dihydrobenzocyclohepten‐5‐ones11b–d and oxygen underwent analogous 4‐electron oxidations. This furnished the substituted 6,7‐benzotropolones11b‐ d. In contrast, the corresponding lithium enolates were inert towards oxygen. The 6,7‐dihydrobenzocyclohepten‐5‐one11d was also accessed differently, namely by a Grubbs‐II catalyst‐mediated RCM/C=C migration tandem reaction of the allyl ortho‐allylaryl ketone73– another 1,8‐diene of sorts (90 % yield)..
| Medienart: |
E-Artikel |
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| Erscheinungsjahr: |
2020 |
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| Erschienen: |
2020 |
| Enthalten in: |
Zur Gesamtaufnahme - volume:2020 |
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| Enthalten in: |
European Journal of Organic Chemistry - 2020(2020), 19, Seite 2929-2955 |
| Beteiligte Personen: |
Kreibich, Michael [VerfasserIn] |
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| BKL: |
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| Anmerkungen: |
© 2020 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim |
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| Umfang: |
27 |
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| doi: |
10.1002/ejoc.202000256 |
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| funding: |
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| Förderinstitution / Projekttitel: |
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| PPN (Katalog-ID): |
WLY005058902 |
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| 520 | |a Four homoallyl ortho‐vinylaryl ketones (10a‐ d) – 1,8‐dienes of sorts – were prepared by several approaches. In the presence of 1–2 mol‐% Grubbs‐II catalyst, they ring‐closed to give 6,7‐dihydrobenzocyclohepten‐5‐ones (11a‐ d) in 90–96 % yield. With SeO2 the parent compound (11a) delivered benzocyclohepten‐5‐one (13a) and/or selenium‐containing compounds (18–22) but no more than traces of 6,7‐benzotropolone (5a). However,5a was accessible from compound11a via the sodium enolate and allowing it to react with a stream of oxygen (43 % yield). The sodium enolates of the substituted 6,7‐dihydrobenzocyclohepten‐5‐ones11b–d and oxygen underwent analogous 4‐electron oxidations. This furnished the substituted 6,7‐benzotropolones11b‐ d. In contrast, the corresponding lithium enolates were inert towards oxygen. The 6,7‐dihydrobenzocyclohepten‐5‐one11d was also accessed differently, namely by a Grubbs‐II catalyst‐mediated RCM/C=C migration tandem reaction of the allyl ortho‐allylaryl ketone73– another 1,8‐diene of sorts (90 % yield). | ||
| 700 | 1 | |a Gemander, Manuel |4 aut | |
| 700 | 1 | |a Peter, David |4 aut | |
| 700 | 1 | |a Yadav, Dharmendra B. |4 aut | |
| 700 | 1 | |a de Koning, Charles B. |4 aut | |
| 700 | 1 | |a Fernandes, Manuel A. |4 aut | |
| 700 | 1 | |a Green, Ivan R. |4 aut | |
| 700 | 1 | |a van Otterlo, Willem A. L. |4 aut | |
| 700 | 1 | |a Brückner, Reinhard |4 aut | |
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