title: An improved method for synthesis of 4,4-dimethylpyrazolone and application to dihydropyridazinone ring formation.
abstract: An improved method for 4,4-dimethylpyrazolone synthesis with t-butylcarbazate was described. The applicability of this method to dihydropyridazinone formation was demonstrated. This method is useful for suppressing the side reaction caused by the high nucleophilicity of hydrazine.
authors.affiliation: Discovery Research Laboratories, Kyorin Pharmaceutical Co. Ltd., 2399–1 Nogi, Nogi-machi, Shimotsuga-gun, Tochigi, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Ochiai
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kojima
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kohno
mesh_terms: D002623:Chemistry Techniques, Analytical; D006834:Hydrazines / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D047069:Pyrazolones / Q000138:chemical synthesis* / Q000737:chemistry; D011724:Pyridazines / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: C572644:4,4-dimethylpyrazolone; D006834:Hydrazines; D047069:Pyrazolones; D011724:Pyridazines; C029424:hydrazine