2-Phenyl-6-chloro-oxazolo [5, 4-c] pyridazine (IV) was prepared by heating 4-amino-3, 6-dichloropyridazine (I) or 4-amino-6-chloro-3-pyridazinol (V) with excess of benzoyl chloride. The synthesis of 4-amino-3-pyridazinol (VI), 5-amino-4-chloro-3-pyridazinol (X), 5-acylamido-4-chloro-3-pyridazinol (XI and XII), and 5-amino-3-pyridazinol (XIII) was also described.
