Bismuth(III) Triflate Catalyzed Three-Component Reactions of Indoles, Ketones, and α-Bromoacetaldehyde Acetals Enable Indole-to-Carbazole Transformation

Yanlong Gu; Wenbo Huang; Shaomin Chen; Xin Wang

doi:10.1021/acs.orglett.8b01707

Bismuth(III) Triflate Catalyzed Three-Component Reactions of Indoles, Ketones, and α-Bromoacetaldehyde Acetals Enable Indole-to-Carbazole Transformation

Org Lett. 2018 Jul 20;20(14):4285-4289. doi: 10.1021/acs.orglett.8b01707. Epub 2018 Jul 6.

Authors

Yanlong Gu^{1

2}, Wenbo Huang¹, Shaomin Chen¹, Xin Wang¹

Affiliations

¹ Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, School of Chemistry and Chemical Engineering, Hubei Key Laboratory of Material Chemistry and Service Failure , Huazhong University of Science and Technology , 430074 , Wuhan , China.
² State Key Laboratory for Oxo Synthesis and Selective Oxidation , Lanzhou Institute of Chemical Physics , 730000 , Lanzhou , China.

PMID: 29978706
DOI: 10.1021/acs.orglett.8b01707

Abstract

A three-component reaction of indoles, α-bromoacetaldehyde acetals, and ketones was developed by using bismuth(III) triflate as the catalyst to realize a straightforward approach for synthesizing carbazole derivatives. The reaction was established mechanistically through the autotandem catalysis of Bi(OTf)₃ in the following two steps: (i) Friedel-Crafts-type alkylation of indole with α-bromoacetaldehyde acetal, which produced a tryptaldehyde-type intermediate and (ii) [4 + 2] annulation of this intermediate with the ketone component.

Publication types

Research Support, Non-U.S. Gov't