Synthesis of new derivatives of pyranoquinolines by a one-pot, three-component reaction

Recently, the use of one-pot, multicomponent reactions (MCRs) have received considerable interest in the synthesis of heterocyclic compounds with biological and pharmacological activities by a route with three or more components, which avoids the spread of poisonous intermediates [1]. Catalysts are the master key toward green chemistry goals [2], and by decreasing the activation energy, catalysts can make a chemical reaction happen in shorter time, more benign, and energy-efficient conditions. The biochemically significant processes are catalyzed. Research into catalysis is a major field in applied science and involves many areas of chemistry, notably organometallic chemistry and materials science. The presence of pyranoquinoline moiety in many alkaloids have attracted serious attention. For instance, antitumor, antimicrobial, anti-inflammatory, antiallergic, antimalarial, inhibition of calcium signaling, and platelet aggregation are some of the unique properties, in behalf of this attraction [3, 4]. In continuation of our interest in the synthesis of new and various heterocyclic compounds [5, 6], an efficient protocol for the synthesis of pyranoquinolines 4 by multicomponent condensation of arylglyoxals 1, ethyl cyanoacetate (2), 4-hydroxyquinolin-2(1H)-one (3) and catalyzed by TEACB in H2O/EtOH under reflux conditions. Furthermore, effect of different catalysts on the reaction was conducted through different catalytic systems including sulfanilic acid, p-toluenesulfonic acid (p-TSA), L-proline, L-cysteine, three ethylamine (Et3N), etc. The best results were obtained using TEACB as a catalyst (Scheme 1).