High temperature coupling of 6-aryl-5-cyano-3-(pyridin-2-yl)-1,2,4-triazines with 2-amino-4-aryloxazoles proceeds as the inverse demand Diels–Alder reaction between the oxazole moiety as dienophile and the 1,2,4-triazine moiety as diene to construct new 4,5-diaryl-6-cyano-3-hydroxypyridin-2-yl fragment. A reaction mechanism is proposed, and the structure of the key-product is proved by the X-ray diffraction analysis.

Synthesis of 5-aryl-2,2'-bipyridines with electron-donor substituents at the C6position by reacting 5-substituted 6-aryl-3-(2-pyridyl)-1,2,4-triazines with 2,5-norbornadiene under high pressure...