The one‐pot, three‐component, synthesis of a new series of 4‐hydroxy‐3‐(2‐arylimidazo[1,2‐a]pyridin‐3‐yl)quinolin‐2(1H)‐ones in the presence of DABCO as a catalyst has been achieved using aryl glyoxal monohydrates, quinoline‐2,4(1H,3H)‐dione, and 2‐aminopyridine in H2O/EtOH under reflux conditions. The cheapness of organocatalyst, simple workup, operational simplicity, regioselectivity, and high yields are some advantages of this protocol.

An improved synthesis of 2-ethyl-5-(2-hydroxy-4-oxoquinolin-3(4H)-ylidene)-6-aryl-5,6-dihydroimidazo[2,1-b][1,3,4]thiadiazol-7-ium hydroxide derivatives 4a–k via the reaction of aryl glyoxal monohydrates 1a–k, quinoline-2,4-diol 2 and 2-amino-[1,3,4]thiadiazole (3) in the presence of Et3N/sulfamic acid in H2O is described. This green protocol is characterized by the use of the readily available catalyst and reactants, short reaction times, operational simplicity and high yields of products. The structures of all compounds were characterized by 1H NMR, 13C NMR and Fourier-transform infrared (FT-IR) spectral data and microanalyses.