5-Benzyloxyindole → 3-(5-Benzyloxyindolyl)propanic acid

Participants

Reaction Steps

To a solution of 5-benzyloxyindole (1.15 g, 5 mmol) in N,N-dimethylformamide (40 mL) was added sodium hydride (200 mg, 5 mmol). After stirring for 30 minutes, ethyl bromopropionate (900 mg, 5.0 mmol) was added and the mixture was stirred at ambient temperature for 1 h, additional sodium hydride (100 mg, 2.5 mmol) was added. After stirring for 10 minutes, additional ethyl bromopropionate (180 mg, 1.0 mmol) was added. The mixture was stirred at ambient temperature overnight. The solvent was removed under high vacuum, the residue was dissolved in water (10 mL) and tetrahydrofuran (10 mL), NaOH (500 mg) was added and stirred for 2 h. After acidifying to pH 4-5, the mixture was extracted with methylene chloride. The methylene chloride layer was washed with brine and dried over Na2SO4. After evaporating the solvent in vacuo, the residue was purified by flash column chromatography (1-5% ethyl acetate in methylene chloride) to give 3-(5-benzyloxyindolyl)propanic acid as white solid. The solid was dissolved in N,N-dimethylformamide (20 mL), K2CO3 (1.0 g) and iodomethane (840 mg) were added and the reaction was stirred at ambient temperature for 3 h. The mixture was concentrated under high vacuum and residue was purified by flash column chromatography (methylene chloride) to give the title compound as a colorless oil (1.10 g, 71%). 1H-NMR (400 MHz, CDCl3) δ 7.47 (d, J=7.3 Hz, 2H), 7.38 (t, J=7.3 Hz, 2H), 7.32 (d, J=7.2 Hz, 1H), 7.23 (d, J=10.2 Hz, 1H), 7.15 (d, J=2.3 Hz, 1H), 7.09 (d, J=3.1 Hz, 1H), 6.96 (dd, J=8.8, 2.5 Hz, 1H), 6.39 (d, J=3.1 Hz, 1H), 5.10 (s, 2H), 4.41 (t, J=6.9 Hz, 2H), 3.66 (s, 3H), 2.81 (t, J=6.8 Hz, 2H).

Provenance & Evidence