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

摘要

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 H-1 NMR, C-13 NMR and Fourier-transform infrared (FT-IR) spectral data and microanalyses.