Potential ambifunctionality of 2‐azidopyrido[1,2‐a] pyrimidin‐4‐one

Abstract 2‐Azidopyrido[1,2‐a]pyrimidin‐4‐one can exit only in the azido form and undergoes cyclo‐addition reaction with 1,3‐dicarbonyl compounds to form 1,2,3‐triazole derivatives. Under the influence of bases or hydrochloric acid the carbonyl group is attacked with subsequent opening of the pyrimidine ring. This causes an immediate cyclization of the azide group to give a tetrazolo derivative. In a similar way a triazole ring can be formed from the appropriate hydrazino derivatives of pyrido[1,2‐a]pyrimidin‐4‐one.