Skeletal Transformation Triggered by C-F Bond Activation after Photochemical Rearrangement of Fluorinated [7]Helicenes
Skeletal Transformation Triggered by C-F Bond Activation after Photochemical Rearrangement of Fluorinated [7]Helicenes
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氟化[7]螺烯光化学重排后 C-F 键激活引发的骨架转变
DOI：
10.1002/chem.202200132
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发表时间：
2022
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;Ryo Igarashi;Hiroshi Katagiri;Takashi Murase
三氟化和四氟化[7]螺旋烯是光不稳定的，并经历双氟原子转移。在这里，我们表明，转移的产品进一步经历了硅胶上的骨架转化。转化开始于硅烷醇表面烯丙基C−F键的活化。然后，所得到的碳阳离子容易地经历与水的区域选择性亲核芳族取代，这取决于氟取代基的位置。六氟-2-丙醇也活化了烯丙基的C−F键，并充当亲核试剂。这些研究结果支持在涉及氟原子的连续转化中产生高度反应性的阳离子亲电中间体。
Tri‐ and tetra‐fluorinated [7]helicenes are photolabile and undergo a double fluorine atom transfer. Herein, we show that the transferred product further undergoes a skeletal transformation on silica gel. The transformation begins with activation of the allylic C−F bond on the silanol surface. Then, the resulting carbocation readily undergoes a regioselective nucleophilic aromatic substitution with water, depending on the position of the fluorine substituents. Hexafluoro‐2‐propanol also activated the allylic C−F bond and acted as a nucleophile. These findings support the generation of a highly reactive cationic electrophilic intermediate in the successive transformations involving fluorine atoms.