Carbazole Based Smaragdyrins: Synthesis, Aromaticity Switching, and Formation of a Spiro-Dimer

Jinchao Chen; Haigen Nie; Yutao Rao; Ling Xu; Mingbo Zhou; Bangshao Yin; Jianxin Song; Atsuhiro Osuka

doi:10.1002/asia.202400029

Carbazole Based Smaragdyrins: Synthesis, Aromaticity Switching, and Formation of a Spiro-Dimer

Chem Asian J. 2024 Apr 16;19(8):e202400029. doi: 10.1002/asia.202400029. Epub 2024 Mar 28.

Authors

Jinchao Chen¹, Haigen Nie¹, Yutao Rao¹, Ling Xu¹, Mingbo Zhou¹, Bangshao Yin¹, Jianxin Song¹, Atsuhiro Osuka¹

Affiliation

¹ Key Laboratory of Chemical Biology and Traditional Chinese Medicine, Ministry of Educational of China, Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, 410081, China.

PMID: 38458988
DOI: 10.1002/asia.202400029

Abstract

Carbazole-incorporated smaragdyrin BF₂-complex 3 was synthesized by S_NAr reaction of 3,5-dibromo-8-mesityl-BODIPY 1 with 3,6-di(tert-butyl)-1,8-di(pyrrol-2-yl)carbazole 2 as a nucleophile. Demetalation of 3 with ZrCl₄ gave the corresponding smaragdyrin free base 4 in a good yield. Oxidations of 3 and 4 with MnO₂ gave smaragdyrins 5 and 6, respectively, both followed by aromaticity switching, since the oxidized products showed a moderate paratropic ring current owing to their 20π-electronic circuits. Further, treatment of 4 with [RhCl(CO)₂]₂ in the presence of NaOAc gave Rh^I complex 7, and oxidation of 3 with RuCl₃ in the presence of triethylamine led to the formation of a spiro dimer product, 8.

Keywords: antiaromaticity; carbazole; oxidation; smaragdyrin.

Abstract

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