Chinese Journal of Catalysis ›› 2019, Vol. 40 ›› Issue (8): 1135-1140.DOI: 10.1016/S1872-2067(19)63370-X

• Communication • Previous Articles     Next Articles

Brönsted acidic ionic liquid catalyzed synthesis of benzo[a]carbazole from renewable acetol and 2-phenylindoles in a biphasic system

Minghao Lia, Fengtian Wua, Yanlong Gua,b   

  1. a Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China;
    b State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, Gansu, China
  • Received:2019-03-13 Revised:2019-04-03 Online:2019-08-18 Published:2019-06-21
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (21761132014, 21872060), the Fundamental Research Funds for the Central Universities of China (2016YXZD033), the Fundamental Research Funds for the Central Universities (2019kfyXJJS072), and Opening fund of Hubei Key Laboratory of Material Chemistry and Service Failure (2017MCF01K).

Abstract: An efficient metal-free strategy for the synthesis of pharmaceutically relevant benzo[a]carbazoles from the derivatives of readily available 2-phenylindole and bio-renewable acetol in an aqueous biphasic system was developed. This protocol employed a sulfone-containing Brönsted acidic ionic liquid as the catalyst, which could be used for five times without a noticeable decrease in its activity and selectivity. Various substituted 2-phenylindoles and α-hydroxyketones participated in the reaction smoothly, with water as the sole byproduct. Mechanistically, the reaction involved the conventional carbon-nucleophile-induced Heyns-type rearrangement and downstream intramolecular olefination.

Key words: Benzo[a]carbazole, Brönsted acid ionic liquid, Bio-renewable acetol, 2-Phenylindole