Aluminum chloride–catalyzed C-alkylation of pyrrole and indole with chalcone and bis-chalcone derivatives

ABSTRACT

The AlCl₃-catalyzed alkylation of pyrrole (2) with chalcone (1a–i) at a ratio of 8:1 in the presence of 10 mol% AlCl₃ gave the solely 2-alkyl pyrroles (3a–i) at room temperature for 12 in good yields. The same reaction was performed with pyrrole (2) and chalcone at a ratio of 1:3 in CH₃CN at rt for 3 h to achieve 2,5-dialkyl pyrroles (4a–f). In addition, the reaction of the pyrrole (2) and indole (7) on 1,4-phenylene bis-chalcones (5a–g) at the ratio of 8:1 at rt for 24 h gave the double-addition products 6a–g and 8a–g in good yields, respectively. The structure of the products was confirmed by ¹H and ¹³C NMR spectroscopy and elemental analysis.

GRAPHICAL ABSTRACT

KEYWORDS:

• Aluminum(III) chloride
• bis-chalcone
• chalcone
• indole
• Michael addition
• pyrrole

Acknowledgments

We are indebted to the Department of Chemistry of Gaziosmanpaşa University.