Fused pyrazolo[3,4-d]pyridazine N-oxides with balanced detonation performance and safety.

A "skeleton-first, oxidation-late" two-step route is reported to synthesize a fused N-oxide (2), featuring a one-pot functionalization strategy introducing nitro and N-oxide moieties. Compound 2 exhibits an exceptionally high density (1.98 g cm-3), excellent detonation velocity (9023 m s-1), and low sensitivities (IS = 30 J, FS > 360 N).