A Short Route to Heteroarylcarbazoles: Synthesis of New Pyrazolylcarbazoles and Carbazolylquinolines

Abstract

A short synthesis of pyrazolylcarbazoles from 9-alkylcarbazoles in three steps is reported. The acetylcarbazoles prepared by the acetylation of carbazoles with acetic anhydride catalyzed by BiCl₃ were converted into chloroaldehydes with Vilsmeier reagent. Condensation of chloroaldehydes with hydrazine followed by cyclization yield the pyrazolylcarbazoles. Carbazolyl chalcones were prepared by the condensation of carbazole-3-aldehyde with o-aminoacetophenone and cyclized to carbazolylquinolone using several catalysts. Cyclization of carbazolyl chalcones with the Vilsmeier reagent yields a mixture of carbazolylquinoline carbaldehydes.

Key words

carbazoles - heterocycles - aldehydes - ring closure - condensation

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