Synthesis 2022; 54(06): 1621-1632
DOI: 10.1055/a-1677-4881
paper

An Oxidant- and Catalyst-Free Synthesis of Dibenzo[a,c]carbazoles via UV Light Irradiation of 2,3-Diphenyl-1H-indoles

Yang Kang
a   Key Laboratory of Applied Surface and Colloid Chemistry (Ministry of Education), School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710119, P. R. of China
,
Rong Hou
a   Key Laboratory of Applied Surface and Colloid Chemistry (Ministry of Education), School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710119, P. R. of China
,
Xiaoyan Min
a   Key Laboratory of Applied Surface and Colloid Chemistry (Ministry of Education), School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710119, P. R. of China
,
Tao Wang
a   Key Laboratory of Applied Surface and Colloid Chemistry (Ministry of Education), School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710119, P. R. of China
,
Yong Liang
b   Department of Molecular Medicine, Beckman Research Institute of City of Hope, Duarte, CA 91010, USA
,
Zunting Zhang
a   Key Laboratory of Applied Surface and Colloid Chemistry (Ministry of Education), School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710119, P. R. of China
› Author Affiliations

We are grateful for financial support from the National Natural Science Foundation of China (No. 21672132).


Abstract

An efficient methodology for the synthesis of dibenzo[a,c]carbazoles via annulation of 2,3-diphenyl-1H-indoles in EtOH under UV light irradiation (λ = 365 nm) along with hydrogen evolution is described. This method exhibits the advantages of mild reaction conditions, no requirement of any oxidants and catalysts, and release of hydrogen as the only byproduct. Notably, the mechanism investigation confirms that the trans-4b,8a-dihydro-9H-dibenzo[a,c]carbazole intermediate could convert into cis-4b,8a-dihydro-9H-dibenzo[a,c]carbazole, which relies on the nitrogen atom of the indole ring. This is followed by intramolecular dehydrogenation which yields the dibenzo[a,c]carbazoles.

Supporting Information



Publication History

Received: 02 September 2021

Accepted after revision: 23 October 2021

Accepted Manuscript online:
23 October 2021

Article published online:
30 November 2021

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