反应详情

A 3 N aqueous KOH solution (6.5 mL, 19.5 mmol, 3 equiv.) was added to a solution of 4-methoxy-2,3-dihydro-indole-1,6-dicarboxylic acid 1-tert-butyl ester 6-methyl ester (2 g, 6.5 mmol, 1 equiv.) in a 1:4 MeOH:tetrahydrofuran solution (20 mL) and the mixture was shaken for 16 hours. The methanol was removed under vacuum and the pH was adjusted to 3 with 3 N aqueous HCl solution. The resulting slurry was diluted with ethyl acetate (20 mL), the organic layer was separated and the aqueous phase was extracted with EtOAc (2×20 mL). The organic layers were combined, dried over Na2SO4 and the solvent was removed under vacuum to afford 4-methoxy-2,3-dihydro-indole-1,6-dicarboxylic acid 1-tert-butyl ester, 1.68 g (88% yield). LC @215 nm; Rt 1.44: 83%, m/z (ES+): 238 (M-Boc+MeCN+H+.); δH (400 MHz; d6-DMSO) 12.58 (1H, br.s) 7.97 (1H, br.s), 6.94 (1H, d), 3.70 (2H, t), 3.61 (3H, s), 2.75 (2H, t), 1.28 (9H, s).

1. customThe methanol was removed under vacuum
2. additionThe resulting slurry was diluted with ethyl acetate (20 mL)
3. customthe organic layer was separated
4. extractionthe aqueous phase was extracted with EtOAc (2×20 mL)
5. dry with materialdried over Na2SO4
6. customthe solvent was removed under vacuum