An interaction of 6-aryl-1,2,4-triazine-5-carbonitriles with 2‑amino-substituted thiazoles and oxazoles has been studied. The difference in the reactivity of these aminoheterocycles depending on the presence of an oxygen or sulfur atom in their composition has been demonstrated. Previously, the 4-aryl-3-hydroxy-2,2'-bipyridines were obtained as products of aza-Diels–Alder reaction between 6-aryl-3-(2-pyridyl)-1,2,4-triazine-5-carbonitriles and 2-amino-4-aryloxazoles. In the present work we have shown that the reaction of 6-aryl-1,2,4-triazine-5-carbonitriles with 2-aminothiazoles led to the products of ipso-substitution of cyano-group. The aza-Diels–Alder reaction of these compounds with 2,5-norbornadiene allowed to obtain (2,2'-bi)pyridines with the thiazol-2-amine moiety at alpha-position.