Studies with enamines and azaenamines: A novel efficient route to 6‐amino‐1,4‐dihydropyridazines and their condensed derivatives

1‐Arylhydrazonopyruvaldehydes 1 react with α,β‐unsaturated nitriles 2 to yield 6‐amino‐1,4‐dihydropyridazines 4 that are converted into pyridazinones 5 via refluxing in an acetic acid/hydrochloric acid mixture and into the ethylidenemalononitrile derivatives 6 on reflux with malononitrile in ethanolic/piperidine solution.