Hydrochloric Acid → 7-(Trifluoromethyl)-1H-indole

Participants

Reaction Conditions

Reaction Steps

To a stirred mixture of 7-trifluoromethyl-1H-indole-2,3-dione (116 mg) in THF (5.00 mL) was added boron trifluoride etherate (0.205 mL, 1.62 mmol) followed by sodium borohydride (71.4 mg, 1.88 mmol). The resulting mixture was stirred at −20° C. for 2 hrs, then water (1 mL) was added and the mixture was stirred at 0° C. for 10 min. The solution was acidified to pH=1 with 2N HCl, warmed to r.t. and stirred at r.t. for 20 min prior to extraction with EtOAc. The extracts were dried over magnesium sulphate, concentrated in vacuo and the residue purified by chromatography over silica gel eluting with hexane to give 7-trifluoromethyl-1H-indole. 1H NMR (400 MHz, CDCl3) δ ppm 6.63-6.68 (1 H, m), 7.20 (1 H, t, J=7.71 Hz), 7.30-7.35 (1 H, m), 7.47 (1 H, d, J=7.33 Hz), 7.83 (1 H, d, J=8.08 Hz), and 8.56 (1 H, br. s.).

Provenance & Evidence