[C:1]([O:5][C:6]([N:8]1[C:16]2[C:11](=[CH:12][CH:13]=[CH:14][CH:15]=2)[CH:10]=[C:9]1[C:17]1[C:18](=[O:35])[N:19]([CH2:27][O:28][CH2:29][CH2:30][Si:31]([CH3:34])([CH3:33])[CH3:32])[CH:20]=[C:21]([C:23]([O:25]C)=[O:24])[CH:22]=1)=[O:7])([CH3:4])([CH3:3])[CH3:2].[OH-].[Li+]>O1CCCC1.O>[C:1]([O:5][C:6]([N:8]1[C:16]2[C:11](=[CH:12][CH:13]=[CH:14][CH:15]=2)[CH:10]=[C:9]1[C:17]1[C:18](=[O:35])[N:19]([CH2:27][O:28][CH2:29][CH2:30][Si:31]([CH3:32])([CH3:33])[CH3:34])[CH:20]=[C:21]([C:23]([OH:25])=[O:24])[CH:22]=1)=[O:7])([CH3:4])([CH3:3])[CH3:2]Intermediate (1b), 2-[5-methoxycarbonyl-2-oxo-1-(2-trimethylsilanyl-ethoxymethyl)-1,2-dihydro-pyridin-3-yl]-indole-1-carboxylic acid tert-butyl ester (2.88 g, 5.78 mmol) was stirred in a mixture of tetrahydrofuran (40 mL) and water (20 mL). Lithium hydroxide (0.469 g, 11.2 mmol) was added and the reaction stirred at reflux for 2 hours. After cooling the reaction mixture was concentrated in vacuo, and the residue was taken up in water and the pH adjusted to 5 with the careful addition of an aqueous 2M hydrochloric acid solution. This aqueous solution was extracted with dichloromethane (×3), and the combined extracts were washed with brine, dried (Na2SO4) and concentrated in vacuo to afford the desired title compound as a yellow solid 2.30 g, 85%.
Loading…