[CH2:1]([C:3]1[S:7][C:6]([C:8]([O:10]C)=[O:9])=[CH:5][C:4]=1[C:12]1[N:16]([CH3:17])[N:15]=[CH:14][CH:13]=1)[CH3:2].[Br:18]N1C(=O)CCC1=O.[OH-].[Na+]>O1CCCC1>[Br:18][C:13]1[CH:14]=[N:15][N:16]([CH3:17])[C:12]=1[C:4]1[CH:5]=[C:6]([C:8]([OH:10])=[O:9])[S:7][C:3]=1[CH2:1][CH3:2]A solution of methyl 5-ethyl-4-(1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylate (300 mg, 1.2 mmol) [Prepared in Example 98] and N-bromosuccinimide (213 mg, 1.2 mmol) in Tetrahydrofuran (5.99 ml) was stirred in a sealed tube for 1 h at 70° C. Aqueous sodium hydroxide (4.0 ml, 23.97 mmol) was added in one portion and the solution stirred an additional 1 h. The reaction mixture was then partitioned between H2O-DCM and the pH of the aqueous phase was adjusted to ˜4 and washed several times with DCM. The combined organic fractions were dried over Na2SO4, concentrated then purified via column chromatography (silica, 20% EtOAC in hexanes) yielding 4-(4-bromo-1-methyl-1H-pyrazol-5-yl)-5-ethyl-2-thiophenecarboxylic acid (378 mg, 1.2 mmol, 100% yield) as a yellow oil: LCMS (ES) m/e 314, 316 (M, M+2)+.
Wird geladen…
