Combinatorial Synthesis of Pyrrolo[3,2-f]quinoline and Pyrrolo[3,2-a]acridine Derivatives via a Three-Component Reaction under Catalyst-Free Conditions

A combinatorial synthesis of pyrrolo[3,21]quinoline and pyrrolo[3,2-c]acridine derivatives is described as a three-component reaction of aromatic aldehyde, 1H-indol-S-amine, and 1,3-dicarbonyl compounds under catalyst-free conditions. The 1,3-dicarbonyl compounds include S,S-dimethylcyclohexane-1,3-dione, cyclopentane-1,37 dione, and 2H-indene-1,3-dione. It is interesting that the designed reactions gave aromatized or unaromatized products, which depend on the reaction temperature and reactants of 1,3-dicarbonyl compounds.