A divergent C−H/N−H annulation of N-aryl urazoles with allylic acetals under ruthenium catalysis is described. By tuning the reaction conditions, including the ruthenium ligand, Zn(OTf)₂ loading, and reaction temperature, the reactivity of π-allylruthenium intermediates can be selectively controlled. Under one set of conditions, γ-addition furnishes seven-membered benzodiazepines, whereas alternative conditions promote α-addition to afford six-membered dihydrocinnolines. The reaction proceeds with good substrate scope and functional group tolerance, providing annulated heterocycles in moderate to high yields. These results demonstrate the utility of allylic acetals as electrophilic partners in ruthenium-catalyzed C−H functionalization and offer an efficient strategy for accessing diverse nitrogen-containing heterocycles.