[Br:1][C:2]1[S:9][C:8]2[C:7]([CH:10]=O)=[C:6]([C:12](OCC)=[O:13])[N:5]([CH3:17])[C:4]=2[CH:3]=1.O.[NH2:19][NH2:20].BrC1SC2C(C=O)=C(C(OCC)=O)NC=2C=1>C(OCCO)C>[CH3:17][N:5]1[C:6]2[C:12]([NH:19][N:20]=[CH:10][C:7]=2[C:8]2[S:9][C:2]([Br:1])=[CH:3][C:4]1=2)=[O:13]The N-methylated product 63 (420 mg, 1.33 mmol) was dissolved in warm 2-ethoxyethanol (26 mL). To a refluxed solution of hydrazine monohydrate (1 mL, 31.9 mmol) and 2-ethoxyethanol (5 mL) under nitrogen was added prepared N-methylated product 62 solution dropwise over a 2 hr period and the solution continued to reflux for additional 1 hr. After cooling to room temperature, about half of the 2-ethoxyethanol was removed under reduced pressure and the remaining solution was refrigerated at −20° C. overnight. The precipitate was filtered and washed with 2-ethoxyethanol to give desired pyridazinone 64 (354 mg, 94%) as a white solid.
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