Ethanol → Ethyl 5-methoxyindole-2-carboxylate
Reaktionsgleichung
[CH3:1][O:2][C:3]1[CH:4]=[C:5]2[C:9](=[CH:10][CH:11]=1)[NH:8][C:7]([C:12]([OH:14])=[O:13])=[CH:6]2.OS(O)(=O)=O.[OH-].[Na+].[CH3:22][CH2:23]O>>[CH2:22]([O:13][C:12]([C:7]1[NH:8][C:9]2[C:5]([CH:6]=1)=[CH:4][C:3]([O:2][CH3:1])=[CH:11][CH:10]=2)=[O:14])[CH3:23]Komponenten
5
Versuchsvorschrift
5-Methoxy-1H-indole-2-carboxylic acid (10 g, 52.3 mmol) in EtOH (400 ml) containing 36% H2SO4 (7 ml) was heated under reflux for 18 hr. After cooling the mixture was neutralised with 2N NaOH (to pH 7) and extracted with EtOAc (3×150ml), the combined extracts were washed with 10% NaHCO3 (2×25 ml), dried (MgSO4), filtered and evaporated to afford 5-methoxy-1H-indole-2-carboxylic acid ethyl ester as a brown solid (9.52 g, 43.3 mmol, 82%) Mp. 154-155° C., MS: m/e=219.1 (M+).