Three-component green synthesis of 6-ethoxycarbonyl-5-methyl-7-(thien-2-yl)-4,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidine, a promising antituberculosis drug

Dihydroazolopyrimidines: Past, Present and Perspectives in Synthesis, Green Chemistry and Drug Discovery

“…However, in this case, the structures of the final compounds were proven only by NMR spectra. Another article deals with the formation of a mixture of two regioisomers involving endocyclic nitrogens in positions 2 and 4 in the reaction of thiophene‐2‐carbaldehyde, ethyl acetoacetate, and 3‐amino‐1,2,4‐triazole in refluxing ethanol [172] . In the same reaction but in boiling water, only a regioisomer involving nitrogen in position 2 was formed.…”

Efficient synthesis of (5-oxo-6,7-dihydro-4H-[1,2,4]triazolo-[1,5-a]pyrimidin-6-yl)acetanilides based on the recyclization of N-arylitaconimides with 3-amino[1,2,4]triazoles

“…19 The same strategy should include three-component reactions of aminotriazole with ketones and Meldrum´s acid, 20 carbonyl and methylene active compounds. 2,11,21- 24 The annulation of a pyrimidine ring to the triazole one is also possible by the condensation of aminotriazoles with dicarbonyl compounds 25 or their synthetic analogs, namely, enaminoesters, 11 alkoxymethylene ketones, 26 ethoxymethylenemalonodinitrile. 11 Procedures based on recyclization reactions are very convenient for the synthesis of polysubstituted polyheterosystems.…”