An efficient synthesis of imidazo[2,1-b][1,3,4]thiadiazol-7-ium hydroxides by a one-pot, three-component reaction in water

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.

A Green and Convenient Route for the Regioselective Synthesis of New Substituted 3-Aryl-5H-indeno[1,2-c]pyridazines as Potential Monoamine Oxidase Type A Inhibitors

Several indeno[1,2-c]pyridazines were efficiently synthesised using the one-pot, three-component reaction of substituted indanones, arylglyoxalmonohydrates, and hydrazine in the presence of 1,5-diazabicyclo[4,3,0]non-5-ene (DBN) in water at room temperature. These substituted 3-aryl indeno[1,2-c]pyridazines can be considered as potential monoamine oxidase type A (MAOA) inhibitors. The advantages of this new strategy are the novelty of the indenopyridazine derivatives, high regioselectivity, use of water as the solvent, no requirement for toxic metal catalysts, and good to excellent yields.