Synthesis of Terminally Fluorinated [7]Helicenes and Their Application to Photochemical Domino Reactions
Synthesis of Terminally Fluorinated [7]Helicenes and Their Application to Photochemical Domino Reactions
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末端氟化[7]螺旋烯的合成及其在光化学多米诺反应中的应用
DOI：
10.1002/asia.202001295
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Takashi Murase
中科院分区：
文献类型：
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作者：
Chikako Matsuda;Yuto Suzuki;Hiroshi Katagiri;Takashi Murase
螺旋烯的分子内Diels−桤木反应使它们的π共轭螺旋形骨架变形。特别地，末端四氟化[7]螺烯（F4-[7]螺烯）经历光诱导的Diels-桤木反应，随后是光诱导的双氟原子转移。在此，我们通过降低氟取代的水平来深入研究这种光化学多米诺过程。在亲双烯体末端带有两个氟原子的F3-[7]螺烯进行光诱导的Diels−桤木反应，但整个多米诺过程变得缓慢。F2-[7]螺烯仅在亲二烯体末端二氟化，也是光不稳定的。结果，两个氟原子足以使光化学多米诺反应发生。X射线晶体学分析表明，F2-[7]螺烯比F4-[7]螺烯压缩程度低，表明末端聚芳醚增强了分子内芳烃-氟代芳烃的堆积相互作用，从而促进了转化。
The intramolecular Diels−Alder reactions of helicenes deform their π‐conjugated screw‐shaped skeletons. In particular, terminally tetrafluorinated [7]helicene (F4‐[7]helicene) undergoes a photoinduced Diels−Alder reaction followed by a photoinduced double fluorine atom transfer. Herein, we thoroughly investigated this photochemical domino process by decreasing the level of fluorine substitution. F3‐[7]Helicenes bearing two fluorine atoms at the dienophile terminal underwent photoinduced Diels−Alder reactions, but the whole domino process became slow. F2‐[7]Helicene, which is difluorinated only at the dienophile terminal, was also photolabile. As a result, two fluorine atoms were sufficient for the photochemical domino reaction to occur. X‐ray crystallographic analysis revealed that F2‐[7]helicene was less compressed than F4‐[7]helicene, indicating that terminal polyfluorination enhanced the intramolecular arene−fluoroarene stacking interactions and thus promoted the transformations.