C([O:5][C:6]([C:8]1[C:13]([O:14][CH2:15][C:16]2[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=2)=[C:12]([OH:22])[N:11]=[C:10]([CH2:23][C:24]2[CH:29]=[CH:28][CH:27]=[C:26]([Cl:30])[C:25]=2[Cl:31])[N:9]=1)=[O:7])(C)(C)C.O.[OH-].[Li+]>O1CCCC1.O>[CH2:15]([O:14][C:13]1[C:8]([C:6]([OH:7])=[O:5])=[N:9][C:10]([CH2:23][C:24]2[CH:29]=[CH:28][CH:27]=[C:26]([Cl:30])[C:25]=2[Cl:31])=[N:11][C:12]=1[OH:22])[C:16]1[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=1To a stirred solution of 5-benzyloxy-2-(2,3-dichlorobenzyl)-6-hydroxypyrimidine-4-carboxylic acid tert-butyl ester (130) (10 g, 21.69 mmol) in a mixture of tetrahydrofuran-water (2:1, 90 mL) was added lithium hydroxide, monohydrate (4.55 g, 108.42 mmol). The mixture was refluxed for 18 h. After completion of the reaction, the volume was reduced by evaporation as much as possible, water was added, and the residue was washed with ethyl acetate to remove non-acidic impurities. The separated aqueous part was acidified with 2(N)HCl to bring the pH to approx. 5 to 6. The acidified aqueous part was extracted with dichloromethane, the separated organic part was dried over sodium sulfate and concentrated under reduced pressure to get 5-benzyloxy-2-(2,3-dichlorobenzyl)-6-hydroxypyrimidine-4-carboxylic acid (131) (7.5 g, 85.32%) as a white solid.
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