Amination of 4‐nitropyridazine 1‐oxides by liquid ammonia/potassium permanganate

Treatment of 4‐nitropyridazine 1‐oxide ( 1a ) 3‐methoxy‐6‐chloro‐4‐nitropyridazine 1‐oxide ( 1b ) or 3,6‐dimethoxy‐4‐nitropyridazine 1‐oxide ( 1c ) with a solution of potassium permanganate in liquid ammonia gives in reasonable‐to‐good yields the corresponding 5‐amino‐4‐nitropyridazine 1‐oxides (75%, 54% and 62%, respectively). 3,6‐Dimethoxypyridazine ( 4a ) and 3‐methoxypyridazine ( 4b ) are converted into the corresponding 4‐aminopyridazines 6a,6b on treatment with potassium amide/liquid ammonia/potassium permanganate (yield 50 and 22% respectively). In the last‐mentioned reaction besides 6b 3,3′‐dimethoxy 4,4′‐bipyridazine (7, 23%) was obtained. It is suggested that the neutral 1:1 σ‐adducts formed between ( 1a–1c ) and liquid ammonia and the anionic σ‐adducts, formed between ( 5a–5b ) and potassium amide are intermediates in this amino‐oxidation reaction.