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Synthesis 2019; 51(16): 3085-3090
DOI: 10.1055/s-0037-1611521
paper
© Georg Thieme Verlag Stuttgart · New York

Iron-Promoted Construction of Indoles via Intramolecular Oxidative C–N Coupling of 2-Alkenylanilines Using Persulfate

Menglan Wang
a   State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Zhejiang University of Technology, Hangzhou 310014, P. R. of China   Email: qawu@zjut.edu.cn
b   State Key Laboratory for Oxo Synthesis and Selective Oxidation, Suzhou Research Institute of LICP, Lanzhou Institute of Chemical Physics (LICP), Chinese Academy of Sciences, Lanzhou 730000, P. R. of China   Email: yhli@licp.cas.cn
,
Yudong Li
b   State Key Laboratory for Oxo Synthesis and Selective Oxidation, Suzhou Research Institute of LICP, Lanzhou Institute of Chemical Physics (LICP), Chinese Academy of Sciences, Lanzhou 730000, P. R. of China   Email: yhli@licp.cas.cn
,
Qing-An Wu*
a   State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Zhejiang University of Technology, Hangzhou 310014, P. R. of China   Email: qawu@zjut.edu.cn
,
Shuping Luo
a   State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Zhejiang University of Technology, Hangzhou 310014, P. R. of China   Email: qawu@zjut.edu.cn
,
Yuehui Li*
b   State Key Laboratory for Oxo Synthesis and Selective Oxidation, Suzhou Research Institute of LICP, Lanzhou Institute of Chemical Physics (LICP), Chinese Academy of Sciences, Lanzhou 730000, P. R. of China   Email: yhli@licp.cas.cn
› Author AffiliationsThe authors acknowledge financial support of this work by the National Natural Science Foundation of China (21633013, 21101109, 21602228) and Natural Science Foundation of Jiangsu Province (BK20160394).
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Publication History

Received: 15 February 2019

Accepted after revision: 01 April 2019

Publication Date:
30 April 2019 (online)

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Abstract

Indole scaffold synthesis relies primarily on oxidative C–H amination of N-protected alkenylanilines for C–N intramolecular cyclization reactions. Herein, for the first time, without N-protection, various readily prepared 2-alkenylanilines were transformed into the desired indole products in good yields by using K2S2O8 as oxidant in the presence of catalytic amounts of FeF2. The K2S2O8/FeF2 system offers a direct and benign synthetic route to 3-arylindoles and it is applicable to a wide range of substituted indoles including drug intermediates.

Key words

indoles - C–N coupling - 2-alkenylanilines - oxidative amination - iron catalysis - 3-arylindoles - unprotected anilines

Supporting Information

    Supporting information for this article is available online at https://doi.org/10.1055/s-0037-1611521.
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