Some Reductive Transformations in the Furazano[3,4‐ d ]pyridazine System. — Formation of 1,2‐Dipyridazinyldiazene Derivatives

Hydrogenation of 4,7‐diarylfurazano[3,4‐ d ]pyridazine 1‐oxides 1 on palladized carbon or platinum oxide yielded 4,5‐diamino‐3,6‐diarylpyridazines 2 and trans ‐1,2‐bis(5‐amino‐3,6‐diaryl‐pyridazin‐4‐yl)diazene 1‐oxides 3 , readily converted by stannous chloride into trans ‐1,2‐bis(5‐amino‐3,6‐diarylpyridazin‐4‐yl)diazenes 6 . Reduction of 1 with sodium tetrahydroborate gave 4,7‐diarylfurazano[3,4‐ d ]pyridazines 5 and 4,7‐diaryl‐4,5‐dihydrofurazano[3,4‐ d ]pyridazine 1‐oxides 4 . The crystal structures of 3a and 4a were solved by X‐ray analysis.