C([O:8][C:9]([C:11]1[NH:12][C:13]([CH3:23])=[C:14]([CH2:17][CH2:18][C:19]([O:21][CH3:22])=[O:20])[C:15]=1[CH3:16])=[O:10])C1C=CC=CC=1>CO>[CH3:22][O:21][C:19]([CH2:18][CH2:17][C:14]1[C:15]([CH3:16])=[C:11]([C:9]([OH:10])=[O:8])[NH:12][C:13]=1[CH3:23])=[O:20]4-(2-methoxycarbonyl-ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylic acid benzyl ester (390 mg, 1.24 mmol) was dissolved in anhydrous MeOH (20 mL). The solution was evacuated and rinsed with argon several times. 120 mg of palladium on charcoal (10%) were added and again the mixture was evacuated and rinsed with argon several times. Finally argon was exchanged by hydrogen (balloon filled with hydrogen) and the mixture was stirred for 3 h at room temperature. The reaction mixture was filtered over celite and the filter residue was washed with MeOH (150 mL). The filtrate was concentrated in vacuo to give pure 4-(2-methoxycarbonyl-ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylic acid as a colorless solid (263 mg). MS (ESI−): m/e=225 [M−H]−.
読み込み中…