Organocatalyzed highly efficient synthesis of densely functionalized pyrrole-fused 1,4-dihydropyridine derivatives

摘要

An organo base catalyzed diverse pyrrole-fused 1,4-dihydropyridines were synthesized. This one-pot, three-component domino reaction of enamino imides, aromatic aldehydes, and malononitrile/ethyl cyanoacetate was achieved by 10 mol% of DMAP under refluxing ethanol. In addition, novel bis-pyrrole-fused 1,4-dihydropyridine derivatives were also prepared by using terephthalaldehyde as a linker instead of simple aromatic aldehydes. This transformation proceeds via Knoevenagel condensation/Michael addition and N-cyclization reaction sequence and have some salient features including the use of a cost-effective catalyst, short reaction time and high atom economy. Moreover, the reusability of the catalyst was also performed up to five runs without any significant loss in activity.