Multicomponent cyclocondensation reactions of aminoazoles, arylpyruvic acids and aldehydes with controlled chemoselectivity

The multicomponent reactions of 3-amino-1,2,4-triazoles/5-aminotetrazole with phenylpyruvic acids and aromatic aldehydes were studied using conventional thermal heating, ultrasonification and microwave dielectric heating. Two different reaction pathways for these cyclocondensations occurring under either kinetic or thermodynamic control were established depending on the temperature regime and building block selection. In case of aminotriazoles, an unprecedented reaction pathway leading to 5-aryl-7-hydroxy-6-phenyl-4,5,6,7-tetrahydro[1,2,4]triazolo[1,5-a]pyrimidine-7-carboxylic acids was found and discussed.