Transient Directing Group Strategy as a Unified Method for Site Selective Direct C4-H Halogenation of Indoles
Guanghua Kuang1,2,3, Dandan Liu3,4, Xuerong Chen3
1Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
Abstract:
A unified method for direct C4-H halogenation of indoles has been accomplished with the assistance of anthranilic acids as suitable transient directing groups. Exclusive site selectivity (one out of five potential reactive sites) as well as good functional group tolerance was obtained to install three kinds of halogen atoms (Cl, Br and I, respectively) by using inexpensive N-halosuccinimides (NXS) as halogen sources under mild conditions. Taking advantage of the rich functional groups in the product, a diversity of nitrogen-containing heterocycles were facily constructed via one-step late-stage derivations.
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