[NH:1]1[C:6]2C=N[O:9][CH2:10][C:5]=2[C:4](=O)[CH2:3][C:2]1=O.C[NH2:14].[C:15](=O)([O-])[NH2:16].C(=O)=O>O1CCOCC1.C(O)C>[CH3:15][NH:16][C:10](=[O:9])[C:5]1[CH:4]=[CH:3][CH:2]=[N:1][C:6]=1[NH2:14]14.96 g (0.09 mol) of 1H-Pyrido[2,3-d]oxazin-2,4-dione was suspended in 138 ml dioxane. The mixture is heated to 40° C. and 17 ml of a 33% solution of methyl amine in ethanol is added dropwise directly into the reaction mixture, to avoid carbamate formation with the evolving CO2. The reaction is allowed to continue for 90 minutes. After cooling down to room temperature, the formed precipitate is removed by filtration and the filtrate is concentrated to dryness. 13.2 g (97%) of 2-aminonicotinic acid methyl amide was isolated (m.p. 140-2° C.).
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