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

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.