Friedlӓnder's synthesis of quinolines as a pivotal step in the development of bioactive heterocyclic derivatives in the current era of medicinal chemistry

In the current scenario of medicinal chemistry, quinoline plays a pivotal role in the design of new heterocyclic compounds with several pharmacological properties, so the search for new synthetic methodologies and their application in drug discovery has been widely studied. So far, many procedures have been performed for the preparation of quinoline scaffolds, among which Friedländer quinoline synthesis plays an important role in obtaining these heterocycles. The Friedländer reaction involves condensation between 2-aminobenzaldehydes and keto-compounds. The quinoline nucleus, once obtained through the Friedländer synthesis, has been extensively modified so that these derivatives can exhibit a large number of biological activities such as anticancer, antimalarial, antimicrobial, antifungal, antituberculosis, and antileishmanial properties. In this work, the focus is on the applicability of the Friedländer reaction in the synthesis of various types of bioactive heterocyclic quinoline compounds, which to date has not been reported in the context of medicinal chemistry. The main part of this review selectively focuses on research from 2010 to date and will present highlights of the Friedländer quinoline synthesis procedures and findings to address biological and pharmacological activities.

An Efficient Synthesis of Bis-indolylindane-1,3-diones, Indan-1,3-diones, and Indene-1,3(2H)-denies Using [Hbim]BF 4 Ionic Medium

We prepared a brand new molecule in one step for the synthesis of bis-indolylindane-1,3-dione and indan-1,3-diones from the reaction of ninhydrin and 3 substituted/unsubstituted indoles using [Hbim]BF₄ ionic liquid in excellent yields. The method was also used for the synthesis of novel indene-1,3(2H)-denies derivatives.

One-pot synthesis of benzo[f]quinolin-3-ones and benzo[a]phenanthridein-5-ones by the photoanuulation of 6-chloropyridin-2-ones and 3-chloroisoquinolin-1-ones to phenylacetylene

The one-pot synthesis of benzo[f]quinolin-3-ones and benzo[a]phenanthridein-5-ones was achieved by the inter- and intramolecular photoannulation of 6-chloropyridin-2-ones and 3-chloroisoquinolin-1-ones with phenylacetylene or tethered phenylacetylene. The reactions were proceeded by photoaddition of 6-chloropyridin-2-ones and 3-chloroisoquinolin-1-ones to phenylacetylene to give the chlorine-substituted stilbenoids, and then 6π electrocyclization of the stilbenoids and oxidation aromatization to afford the polycyclic products.