Nickel-Catalyzed [5+2] Cycloaddition of 10π-Electron Aromatic Benzothiophenes with Alkynes To Form Thermally Metastable 12π-Electron Nonaromatic Benzothiepines
Nickel-Catalyzed [5+2] Cycloaddition of 10π-Electron Aromatic Benzothiophenes with Alkynes To Form Thermally Metastable 12π-Electron Nonaromatic Benzothiepines
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DOI：
10.1021/jacs.9b07948
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发表时间：
2019-08-14
影响因子：
15
通讯作者：
Matsubara, Seijiro
中科院分区：
文献类型：
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作者：
Inami, Tasuku;Takahashi, Toshifumi;Matsubara, Seijiro
报道了镍催化的五元苯并噻吩和炔的[5+2]环加成反应，通过脱芳构化反应得到七元苯并硫杂环庚三烯。该反应涉及炔与含硫芳族杂环的硫醇羰基化，通过扩环得到含硫杂环化合物。因此，该方法有利于发散地获得热亚稳态苯并硫杂环庚三烯。通过原位X射线吸收精细结构谱和密度泛函理论计算证实了由苯并噻吩中的C-S键与镍（0）氧化加成形成的硫代镍-乳酸中间体的结构。
The nickel-catalyzed formal [5+2] cycloaddition of five-membered benzothiophenes and alkynes giving seven-membered benzothiepines via unprecedented dearomatization is reported. The reaction involves the carbothiolation of alkynes with sulfur-containing aromatic heterocycles affording sulfur-containing heterocyclic compounds via ring expansion. As a result, this method facilitates divergent access to thermally metastable benzothiepines. The structure of the thianickelacycle intermediate, which is formed via oxidative addition of the C-S bond in benzothiophenes to nickel(0), was confirmed by in situ X-ray absorption fine structure spectroscopy and density functional theory calculation.