[OH-].[Li+].[NH2:3][C:4]1[C:9]([F:10])=[C:8]([CH2:11][CH3:12])[N:7]=[C:6]([C:13]([O:15]C)=[O:14])[C:5]=1[Cl:17]>O.O1CCCC1>[NH2:3][C:4]1[C:9]([F:10])=[C:8]([CH2:11][CH3:12])[N:7]=[C:6]([C:13]([OH:15])=[O:14])[C:5]=1[Cl:17]A solution of lithium hydroxide (0.49 g, 11.73 mmol) in water (25 mL) was added to a solution of methyl 4-amino-3-chloro-6-ethyl-5-fluoropyridine-2-carboxylate (1.36 g, 5.86 mmol) in tetrahydrofuran (25 mL). The mixture was vigorously stirred at room temperature overnight and was then concentrated to half volume. After adding water the reaction mixture was washed once with ethyl acetate to remove unreacted starting material. The aqueous layer was then acidified to pH<3 with 1N HCl, concentrated and the residue partitioned between tetrahydrofuran and brine. The aqueous layer was discarded and the organic layer concentrated and dried under vacuum to provide 4-amino-3-chloro-6-ethyl-5-fluoropyridine-2-carboxylic acid (1.01 g, 4.60 mmol) as a white solid, mp 144-145° C.
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