[C:1]([C:4]1[CH:9]=[CH:8][C:7]([Cl:10])=[CH:6][N:5]=1)(=O)[CH3:2].[C:11]([OH:15])(=O)[CH:12]=O.C(=O)([O-])[O-].[K+].[K+].O.[NH2:23][NH2:24]>CO.O>[Cl:10][C:7]1[CH:8]=[CH:9][C:4]([C:1]2[CH:2]=[CH:12][C:11](=[O:15])[NH:23][N:24]=2)=[N:5][CH:6]=1To a slurry of 5.05 g of 2-acetyl-5-chloropyridine (32.4 mmol) in 36 mL of methanol at room temperature was added 60 mL of water and 4.8 g of 50% glyoxylic acid (32.4 mmol). Potassium carbonate (8.96 g, 2 equivalents) was added carefully (foaming), and the reaction mixture was stirred overnight at room temperature under nitrogen. The next day, the slurry was partially stripped on the rotovap to remove methanol (maximum bath temperature 30° C.). The slurry was transferred to a separatory funnel and extracted twice with methylene chloride. The aqueous phase was transferred back to a round bottom flask and treated carefully with 13.7 mL of acetic acid (foaming) followed by 1.9 g of hydrazine hydrate (38 mmol). The reaction mixture was refluxed for 2 hours. It became very dark. While cooling, potassium carbonate was carefully added until the pH was 7. The reaction mixture was cooled to room temperature, then filtered and washed with water. The solids were dried in a vacuum oven at 50° C. The product was 4.13 g of a fine black solid. The NMR data is as follows: 300 MHz 1H NMR (DMSO d-6, TMS=0 ppm) 7.10 (d, 1H); 7.75 (d, 1H); 8.11 (d, 1H) 8.70 (d, 1H); 13.4 (bs, 1H). The yield of pyridazinone was 61%.
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