Synthesis of new indole substituted pyrazolo[3,4-b]quinoline via a sequential four component reaction

Among nitrogen-containing heterocyclic compounds, pyrazolo quinolines have paid significant interest in medicinal chemistry due to uniqueness in biological activities such as antiviral, antimicrobial and antimalarial activities, and also used as optical brightener, dyestuff and as colorant.1,2 In this paper, new pyrazolo[3,4-b]quinoline derivatives substituted with indole 5 have been prepared, based on the reaction of enamines and Michel acceptor via the one-pot, multicomponent reaction of dimedone 1, various aniline 2, indole-3-carboxaldehyde 3, and pyrazolone as an enolizable C−H activated compound 4, under mild conditions respectively in the stoichiometric melt and H2O in the presence of piperidine (Scheme 1). In order to increase the therapeutic properties of pyrazolo[3,4-b]quinoline, we synthetically attached the indole ring with a broad range of biological activity in medicinal chemistry including antihypertensive, antiproliferative, antiviral, antitumor, analgesic, anti-inflammatory, antimicrobial and antifungal activities.3

Keywords:

Pyrazolo[3 , 4-b]quinoline , Indole-3-carboxaldehyde , Michel acceptor , Enamine.