6,7-benzotropolone syntheses based on ring-closing metatheses and four-electron oxidations

Abstract: 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 compound 11a 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‐ones 11b–d and oxygen underwent analogous 4‐electron oxidations. This furnished the substituted 6,7‐benzotropolones 11b ‐d . In contrast, the corresponding lithium enolates were inert towards oxygen. The 6,7‐dihydrobenzocyclohepten‐5‐one 11d was also accessed differently, namely by a Grubbs‐II catalyst‐mediated RCM/C=C migration tandem reaction of the allyl ortho‐allylaryl ketone 73 – another 1,8‐diene of sorts (90 % yield)

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch
• Notes: European journal of organic chemistry. - 2020, 19 (2020) , 2929-2955, ISSN: 1099-0690

Classification and Topics

• Keyword: Isomerisierungsreaktion ; Ringschlussmetathese ; Sauerstoff ; Aromaten

Contributors, Places and Time

• Event: Veröffentlichung
• (where): Freiburg
• (who): Universität
• (when): 2020
• Creator: Kreibich, Michael ; Gemander, Manuel ; Peter, David ; Yadav, Dharmendra B. ; Koning, Charles B. ; Fernandes, Manuel A. ; Green, Ivan ; Otterlo, Willem van ; Brückner, Reinhard

Further information

• DOI: 10.1002/ejoc.202000256
• URN: urn:nbn:de:bsz:25-freidok-1663795
• Rights: Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 25.03.2025, 1:54 PM CET