Synthesis 2022; 54(08): 2019-2030
DOI: 10.1055/a-1681-7480
paper

Iron-Catalyzed One-Pot Synthesis of Indole-Tethered Tetrasubstituted Pyrroles and Their Transformations to Indolizino[8,7-b]indole Derivatives

Xue Xiao
a   Laboratory of Asymmetric Synthesis, Chongqing University of Arts and Sciences, 319 Honghe Ave., Yongchuan, Chongqing, 402160, P. R. of China
b   Tonichem Pharmaceutical Technology Co., Ltd, Huizhou, 516008, P. R. of China
,
Xiao-Hui Chen
a   Laboratory of Asymmetric Synthesis, Chongqing University of Arts and Sciences, 319 Honghe Ave., Yongchuan, Chongqing, 402160, P. R. of China
b   Tonichem Pharmaceutical Technology Co., Ltd, Huizhou, 516008, P. R. of China
,
Xian-Xun Wang
b   Tonichem Pharmaceutical Technology Co., Ltd, Huizhou, 516008, P. R. of China
,
Wan-Zhen Li
a   Laboratory of Asymmetric Synthesis, Chongqing University of Arts and Sciences, 319 Honghe Ave., Yongchuan, Chongqing, 402160, P. R. of China
,
Hai-Lei Cui
a   Laboratory of Asymmetric Synthesis, Chongqing University of Arts and Sciences, 319 Honghe Ave., Yongchuan, Chongqing, 402160, P. R. of China
› Author Affiliations
We are grateful for the support provided for this study by the National Natural Science Foundation of China (21871035, 21502013) and the Chongqing Research Program of Basic Research and Frontier Technology (cstc2019jcyj-msxm2653).


Abstract

We have developed an efficient iron-catalyzed one-pot reaction of tryptamines, ynones and nitroolefins, affording indole-tethered tetrasubstituted pyrroles in acceptable to good yields. Other aromatic and aliphatic amines can also be utilized in this process, delivering the corresponding highly functionalized tetrasubstituted pyrroles. Indolizino[8,7-b]indole derivatives could be obtained through TFA-, TfOH- or Fe(OTf)3-mediated cyclizations via dearomatization of indole. Unexpected dibrominated products, 7,9-dibromo-6,11-dihydro-5H-indolizino[8,7-b]indoles, were formed when trimethylphenylammonium tribromide (PTAP) was employed as electrophilic cyclization promoter.

Supporting Information



Publication History

Received: 27 September 2021

Accepted after revision: 28 October 2021

Accepted Manuscript online:
28 October 2021

Article published online:
06 December 2021

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