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

Abstract

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.

Enantioselective Construction of Chiral THIQUINOL and Its Derivatives via Chiral Phosphoric Acid Catalysis

“…Chiral isoquinoline and its derivatives are crucial components in many biologically active natural products, − pharmaceuticals, − and functional molecules. − They are also used as chiral ligands or catalysts in asymmetric synthesis. − Owing to the significance of this structural motif, much effort has been made toward the efficient synthesis of isoquinoline derivatives, especially those with a teriary stereocenter or chiral axis at the C1 position. Among these achievements, the addition of nucleophiles to iminium or acyl iminium ions has been shown to be an effective method for synthesizing C1-sustituted isoquinoline derivatives. − …”