Synthesis of N‐Alkyl and N‐H‐Carbazoles through SNAr‐Based Aminations of Dibenzothiophene Dioxides

Alkyl amines have become available for the synthesis of diverse N‐alkyl carbazoles through twofold SNAr aminations of dibenzothiophene dioxides by using alkali metal bases. Of particular importance is the choice of counter cations on alkali metal bases, that is, i) the use of Li base for the efficie...

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Bibliographic Details
Published in:Chemistry : a European journal 2019-11, Vol.25 (65), p.14780-14784
Main Authors: Kaga, Atsushi, Nogi, Keisuke, Yorimitsu, Hideki
Format: Article
Language:English
Subjects:
Alkali metals
amination
Amines
Base metal
Carbazoles
Cations
Chemistry
Dibenzothiophene
dibenzothiophene dioxides
Dioxides
nucleophilic aromatic substitution
Phenethylamine
Phenylethylamine
Synthesis
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Summary:Alkyl amines have become available for the synthesis of diverse N‐alkyl carbazoles through twofold SNAr aminations of dibenzothiophene dioxides by using alkali metal bases. Of particular importance is the choice of counter cations on alkali metal bases, that is, i) the use of Li base for the efficient intermolecular reaction and ii) the sequential addition of heavier alkali metal bases (Na, K, or Cs) to promote intramolecular cyclization in a one‐pot manner. This protocol also enables the cascade synthesis of N‐H‐carbazoles by using 2‐phenylethylamine by removal of the 2‐phenethyl group from N‐(2‐phenethyl) carbazoles in a single operation. One‐pot, two‐fold SNAr aminations of dibenzothiophene dioxides with alkyl amines by using a LiN(SiMe3)2/KN(SiMe3)2 system have been developed for the synthesis of diverse N‐alkyl carbazoles. This protocol also enables the cascade synthesis of N‐H‐carbazoles through concomitant removal of the 2‐phenethyl group from N‐(2‐phenethyl)carbazoles in a single operation (see scheme).
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.201903916