Pseudo Four-Component Synthesis of 5,6-Dihydroindolo[2,1-a]isoquinolines

• DOI: 10.1021/acs.joc.3c02133
• Publication Date: 2024-01-05T03:04:55Z
• Authors: Almira R. Miftyak...; Tatiana N. Borisova; Artem N. Fakhrutd...; Valentina V. Ilyu...; Alexander A. Titov; Ilya V. Efimov; Victor A. Tafeenko; Alexey V. Varlamov; Leonid G. Voskres...

An easy synthesis of novel highly functionalized 5,6-dihydroindolo[2,1-a]isoquinolines was developed via a pseudo four-component domino reaction of 1-aroyl-3,4-dihydroisoquinolines, terminal α,β-ynones, and malononitrile. The selective formation of this biologically relevant heterocyclic core was achieved using a one-pot approach under microwave irradiation. The formation of the same skeleton through the reaction of 5,6-dihydropyrrolo[2,1-a]isoquinolines with malonic acid dinitrile supports the proposed mechanism, involving the intermediate product of the three-component reaction. Furthermore, the disproval of an alternative reaction pathway, which involved the dimerization of malononitrile followed by three-component transformation, was demonstrated. Introducing the malononitrile dimer as a CH acid resulted in the formation of a different pyrido[3',4':4,5]pyrrolo[2,1-a]isoquinoline core. Additionally, the synthesized 5,6-dihydroindolo[2,1-a]isoquinolines were examined for their photophysical properties, revealing their attractive luminescent characteristics.