Synthesis of pyridine and 2,2′-bipyridine derivatives from the aza Diels–Alder reaction of substituted 1,2,4-triazines

Amidrazone and the tricarbonyl derivatives reacted in boiling ethanol in the presence of 2,5-norbornadiene giving the pyridine derivatives respectively (59–72%) and in the presence of 2,3-dihydrofuran yielding the lactones (39–44%). The 2,2′-bipyridine derivatives were similarly obtained in good yield (81–87%) from the reaction of amidrazone and tricarbonyl derivatives in the presence of 2,5-norbornadiene .