The Wittig reaction of certain 2-(alkylidenehydrazono) propylidenephosphoranes with ketenes provides a general route to l-oxo-3, 4-diaza-2, 4, 6, 7-octatetraenes (allenyl azines). The allenyl azines undergo a facile intramolecular thermal cycloaddition reaction to yield pyrazolo [5, 1-~]-1, 4-oxazines and/or 4, 9-dihydropyrazolo [1, 5-b] isoquinolines depending on the nature of the substituents introduced via the ketene.