Cycloaromatization of a non-conjugated polyenyne system: Synthesis of 5H-benzo[d]fluoreno[3,2-b]pyrans via diradicals generated from 1-[2-{4-(2-alkoxymethylphenyl)butan-1,3-diynyl}]phenylpentan-2,4-diyn-1-ols and trapping evidence for the 1,2-didehydrobenzene diradical
Cycloaromatization of a non-conjugated polyenyne system: Synthesis of 5H-benzo[d]fluoreno[3,2-b]pyrans via diradicals generated from 1-[2-{4-(2-alkoxymethylphenyl)butan-1,3-diynyl}]phenylpentan-2,4-diyn-1-ols and trapping evidence for the 1,2-didehydrobenzene diradical
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DOI：
10.1016/s0040-4039(97)00785-5
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发表时间：
1997-06-02
影响因子：
1.8
通讯作者：
Ueda, I
中科院分区：
文献类型：
--
作者：
Miyawaki, K;Suzuki, R;Ueda, I
非共轭四炔类化合物1经热分子内环化成非苯基二基(23)，然后在25℃下进行自由基环芳构化，得到7-脱氢-5H-苯并[d]荧并[3，2-b]吡喃单环(24)和烷基(25)。24的抽氢反应得到5H-苯并[d]荧并[3，2-b]吡喃(3)，它们与25反应生成4。另一方面，2得到5H-荧醇(5)，表明1，2-二脱氢苯二自由基中间体(28和29)的形成。这些自由基通过与芳香族二烯菲反应而被捕获为相应的Diels-Alder类型的产物。(C)1997年爱思唯尔科学有限公司。
Non-conjugated tetraynes 1 undergo thermal intramolecular cyclization to non-benzenoid diradicals (23) followed by radical cycloaromatization at 25 degrees C to provide 7-dehydro-5H-benzo[d]fluoreno[3,2-b]pyran monoradical(24) and alkyl radicals(25). Hydrogen abstraction of 24 gives 5H-benzo[d]fluoreno[3,2-b]pyrans (3) which are converted to 4 by reaction with 25. On the other hand, 2 gives 5H-fluorenol (5), indicating the formation of 1,2-didehydrobenzene diradical intermediates (28 and 29). These radicals are trapped as the corresponding Diels-Alder-type products by reaction with an aromatic diene, anthracene. (C) 1997 Elsevier Science Ltd.