6,7‐Benzotropolone Syntheses Based on Ring‐Closing Metatheses and Four‐Electron Oxidations
6,7‐Benzotropolone Syntheses Based on Ring‐Closing Metatheses and Four‐Electron Oxidations
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DOI：
10.1002/ejoc.202000256
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发表时间：
2020-03
影响因子：
2.8
通讯作者：
Michael Kreibich;M. Gemander;D. Peter;Dharmendra B. Yadav;C. D. de Koning;M. Fernandes;I. Green
中科院分区：
文献类型：
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作者：
Michael Kreibich;M. Gemander;D. Peter;Dharmendra B. Yadav;C. D. de Koning;M. Fernandes;I. Green
用几种方法制备了四种全烯丙基-乙烯基酮(10a - d) - 1,8 -二烯。在1-2 mol - %的Grubbs - II催化剂存在下，它们环合生成6,7 -二氢苯并环庚烯- 5 -酮（11a - d），产率为90 - 96%。母体化合物（11a）递送苯并环庚烯- 5 -酮（13a）和/或含硒化合物（18-22），但不超过痕量的6,7 -苯并曲polone （5a）。然而，5 - a可以通过烯酸钠从化合物11中获得，并允许它与氧气流反应（产率43%）。取代的6,7 -二氢苯并环庚烯- 5 -溴代烯醇酸钠与氧发生类似的4 -电子氧化。这就得到了取代的6,7‐苯并唑酮11b‐d。相反，相应的烯醇化锂对氧是惰性的。6,7 -二氢苯并环庚烯- 5 - one11也以不同的方式得到，即通过Grubbs - II催化剂介导的烯丙基-烯丙基酮73 -另一种1,8 -二烯的RCM/C=C迁移串联反应（产率90%）。
Four homoallylortho‐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 SeO2the 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,5awas accessible from compound11avia 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–dand 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‐one11dwas also accessed differently, namely by a Grubbs‐II catalyst‐mediated RCM/C=C migration tandem reaction of the allylortho‐allylaryl ketone73– another 1,8‐diene of sorts (90 % yield).