Zhao Hua, Shen Peng, Sun Dongru, Zhai Hongbin, Zhao Yufen
Institute of Drug Discovery Technology, Qian Xuesen Collaborative Research Center of Astrochemistry and Space Life Sciences, Ningbo University, Ningbo 315211, Zhejiang, China.
The State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
J Org Chem. 2021 Jul 2;86(13):9189-9199. doi: 10.1021/acs.joc.1c00494. Epub 2021 Jun 11.
The regioselective functionalization reaction of unprotected carbazoles with donor-acceptor (D-A) cyclopropanes has been demonstrated for the first time. With Sc(OTf) as Lewis acid catalyst, the N-H functionalization of carbazoles takes place through a highly selective nitrogen-initiated nucleophilic ring opening reaction. Significantly, by engaging TfOH as Brønsted acid catalyst, a straightforward C-H functionalization at the 3-position of the unprotected carbazole proceeds via Friedel-Crafts-type addition. This strategy facilitates the diversity-oriented synthesis of carbazole-containing heterocycles and expands the novel application of D-A cyclopropanes.
首次证明了未保护的咔唑与供体-受体（D-A）环丙烷的区域选择性官能团化反应。以Sc(OTf)作为路易斯酸催化剂，咔唑的N-H官能团化通过高度选择性的氮引发亲核开环反应进行。值得注意的是，通过使用TfOH作为布朗斯特酸催化剂，未保护咔唑3位的直接C-H官能团化通过傅克型加成反应进行。该策略促进了含咔唑杂环的多样性导向合成，并扩展了D-A环丙烷的新应用。
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