[Br:1][C:2]1[CH:3]=[C:4]2[C:8](=[CH:9][C:10]=1[CH3:11])[NH:7][C:6]([C:12]([O:14]CC)=[O:13])=[C:5]2[CH3:17].BrC1C(C)=C2C(=CC=1)NC(C([O-])=O)=C2C.[OH-].[K+]>CCO>[Br:1][C:2]1[CH:3]=[C:4]2[C:8](=[CH:9][C:10]=1[CH3:11])[NH:7][C:6]([C:12]([OH:14])=[O:13])=[C:5]2[CH3:17]A 1:1 isomeric mixture of ethyl 5-bromo-3,6-dimethyl-1H-indole-2-carboxylate and 5-bromo-3,4-dimethyl-1H-indole-2-carboxylate (5.36 g, 18.1 mmol) was dissolved in EtOH (20 mL) and KOH (3.6 g, 54 mmol). The mixture was refluxed for 3 h and gave 4.67 g (99%) of a 1:1 isomeric mixture of the corresponding acids. The mixture was acidified and the precipitate that formed was filtered and dried at 120° C. to afford the title compound (4.39 g, 90.6%). 1H NMR (300 MHz, DMSO-d6) δ, mix 12.96 (s, 1H), 11.50 and 11.40 (2s, 2×0.5H), 7.85 and 7.33 (2s, 2×0.5H), 7.34 and 7.16 (2d, J=8.7 Hz, 2×0.5H), 2.76, 2.73, 2.49 and 2.47 (4s, 4×1.5H).
Wird geladen…
