[C:1]([O:5][C:6]([N:8]1[CH2:13][CH2:12][N:11]([C:14]2[C:19]([Cl:20])=[CH:18][C:17]([C:21]([OH:23])=[O:22])=[CH:16][N:15]=2)[CH2:10][CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].[C:24]([O-])([O-])=O.[K+].[K+].CI>CN(C=O)C>[C:1]([O:5][C:6]([N:8]1[CH2:9][CH2:10][N:11]([C:14]2[C:19]([Cl:20])=[CH:18][C:17]([C:21]([O:23][CH3:24])=[O:22])=[CH:16][N:15]=2)[CH2:12][CH2:13]1)=[O:7])([CH3:4])([CH3:2])[CH3:3]To a mixture of 4-(5-carboxy-3-chloro-pyridin-2-yl)-piperazine-1-carboxylic acid tert-butyl ester from step (a) above (1.1 g, 3.22 mmol) and K2CO3 (0.67 g, 4.83 mmol) in DMF (10 mL) was added dropwise MeI (0.3 mL, 4.83 mmol) with stirring at room temperature. The reaction mixture was stirred at room temperature for 16 h, quenched with 20 mL of satd. aq. solution of NaHCO3 and extracted with EtOAc (50 mL). The organic extract was washed with brine (20 mL), dried over Na2SO4, filtered and concentrated in vacuo. The residue was purified by column chromatography (gradient 30% to 50% EtOAc in hexane) to give the title compound as white solid.
Wird geladen…
