C([O:3][C:4]([C:6]1[CH:7]=[N:8][N:9]([CH2:11][C:12]2[CH:17]=[CH:16][C:15]([C:18](C)(C)[O:19][SiH2]C(C)(C)C)=[CH:14][CH:13]=2)[CH:10]=1)=[O:5])C.O.[OH-].[Li+]>CO.O>[OH:19][CH2:18][C:15]1[CH:16]=[CH:17][C:12]([CH2:11][N:9]2[CH:10]=[C:6]([C:4]([OH:5])=[O:3])[CH:7]=[N:8]2)=[CH:13][CH:14]=1A mixture of 1-[4-(tert-Butyl-dimethyl-silanyloxymethyl)-benzyl]-1H-pyrazole-4-carboxylic acid ethyl ester (630 mg, 1.4 mmol) and lithiumhydroxide-hydrate (119 mg, 2.8 mmol) in 20 mL MeOH and 10 mL water was stirred at RT for 32 h. The mixture was evaporated in vacuo and the aq. layer was acidified with 1 N aq. HCl. After extraction with ethyl acetate, the organic layer was dried over MgSO4 and evaporated to yield the crude product which was used in the next step without further purification. 1H-NMR (DMSO-d6, 400 MHz) 12.3 (bs, 1H), 8.36 (s, 1H), 7.81 (s, 1H), 7.23-7.31 (s, 4H), 5.34 (s, 2H), 5.18 (t, 1H), 4.47 (s, 2H).
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