[CH3:1][C:2]1[C:3]2[N:4]([N:12]=[C:13]([C:15]3[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=3)[N:14]=2)[CH:5]=[CH:6][C:7]=1[C:8]([O:10]C)=[O:9].O.[OH-].[Li+].Cl>O1CCCC1.O>[CH3:1][C:2]1[C:3]2[N:4]([N:12]=[C:13]([C:15]3[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=3)[N:14]=2)[CH:5]=[CH:6][C:7]=1[C:8]([OH:10])=[O:9]
A mixture of methyl 8-methyl-2-phenyl-[1,2,4]triazolo[1,5-a]pyridine-7-carboxylate (634 mg, 2.37 mmol) and lithium hydroxide monohydrate (398 mg, 9.49 mmol) in tetrahydrofurane (15 ml) and water (5 ml) is stirred for 3 days at 25° C. The mixture is diluted with water, acidified to pH=0 with hydrochloric acid 37% and extracted with ethyl acetate; the organic layer is washed with water and brine, dried with magnesium sulfate and the solvent is evaporated affording 8-methyl-2-phenyl-[1,2,4]triazolo[1,5-a]pyridine-7-carboxylic acid (710 mg, 118%) as a white solid. mp.: >250° C. MS: m/z=254.1 (M+H+).
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