Trifluoroacetic acid → 3-(6-hydroxy-1,3-benzodioxol-5-yl)-7-(trifluoromethyl)-1,3-dihydro-2H-indol-2-one

Participants

Reaction Steps

To a solution of 3-hydroxy-3-(6-hydroxy-1,3-benzodioxol-5-yl)-7-(trifluoromethyl)-1,3-dihydro-2H-indol-2-one (7.06 g, 20.0 mmol) in anhydrous trifluoroacetic acid (21.0 mL, 9.12 g, 80 mmol) was added triethylsilane (12.8 mL, 9.30 g, 80.0 mmol) at ambient temperature. The reaction mixture was stirred at ambient temperature for 0.5 h. The reaction mixture was quenched with water (50.0 mL). The mixture was extracted with ethyl acetate (2×150 mL). The organic solution was washed with saturated ammonium chloride (3×75 mL), dried over sodium sulfate and filtered. The filtrate was concentrated in vacuo to dryness. The residue was triturated with diethyl ether to afford 3-(6-hydroxy-1,3-benzodioxol-5-yl)-7-(trifluoromethyl)-1,3-dihydro-2H-indol-2-one (5.94 g, 88%) as colourless solid: 1H NMR (300 MHz, DMSO-d6) δ 10.81 (s, 1H), 9.25 (br, 1H), 7.37 (d, J=8.0 Hz, 1H), 7.12 (d, J=7.3 Hz, 1H), 6.98 (dd, J=7.7, 7.7 Hz, 1H), 6.71 (s, 1H), 5.88 (s, 2H), 4.65 (s, 1H); 13C NMR (75 MHz, DMSO-d6) δ 178.7, 150.5, 147.4, 140.5, 140.1, 133.3, 127.8, 124.3, 124.2, 121.6, 115.5, 110.8, 110.3, 101.3, 98.2, 48.1; MS (ES+) m/z 338.3 (M+1).

Provenance & Evidence