Trifluoroacetic acid → 2-ethyl-4-methoxy-1H-indole
Reaction equation
C(OC(=O)[NH:7][C:8]1[CH:13]=[C:12](OC)[CH:11]=[CH:10][C:9]=1[CH2:16][C:17](=O)[CH2:18][CH3:19])(C)(C)C.[C:22](O)(C(F)(F)F)=[O:23]>C1COCC1>[CH2:18]([C:17]1[NH:7][C:8]2[C:9]([CH:16]=1)=[C:10]([O:23][CH3:22])[CH:11]=[CH:12][CH:13]=2)[CH3:19]Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Procedure
To a solution of [5-methoxy-2-(2-oxo-butyl)-phenyl]-carbamic acid t-butyl ester 73b (1.36 g, 4.65 mmole) in 10 ml THF was added 4 ml TFA. The reaction mixture was stirred at room temperature for 5 h, quenched with 50 ml H2O and extracted with EtOAc. The organic layer was dried over MgSO4 and concentrated. The residue was purified by flash column chromatography (10–15% EtOAc in hexane) to give pale yellow solid (1.36 g, 73%). 1H NMR (CDCl3) δ 7.75 (1H, bs), 7.49 (1H, d, J=8.6 Hz), 6.81 (1H, s), 6.73 (1H, d, J=8.6 Hz), 3.83 (3H, s), 2.75 (2H, q, J=7.5 Hz), 1.32 (3H, t, J=7.5 Hz). ESIMS (MH+): 272.10.