3,4-Difluorophenol → 3-(4,5-difluoro-2-hydroxyphenyl)-1-(diphenylmethyl)-3-hydroxy-1,3-dihydro-2H-indol-2-one

Beteiligte Stoffe

Reaktionsschritte

To a solution of 3,4-difluorophenol (10.33 g, 79.4 mmol) in anhydrous tetrahydrofuran (60 mL) at 0° C. under nitrogen was added isopropyl magnesium chloride (39.7 mL, 79.4 mmol), and the solution was stirred at ambient temperature for 3 h. Tetrahydrofuran was removed by rotary evaporation, and the residue was redissolved in anhydrous dichloromethane (140 mL). The solution was cooled to 0° C. under nitrogen, then N-benzhydryl isatin (13.77 g, 43.9 mmol) was added and the reaction mixture was allowed to warm to ambient temperature. After 3 days, the reaction was quenched with aqueous saturated ammonium chloride (60 mL) and concentrated in vacuo. The residue was re-dissolved in ethyl acetate (150 mL) and washed with water (2×100 mL) and brine (100 mL), dried over sodium sulfate, filtered, and concentrated. The residue was precipitated from diethyl ether to yield 3-(4,5-difluoro-2-hydroxyphenyl)-1-(diphenylmethyl)-3-hydroxy-1,3-dihydro-2H-indol-2-one (12.08 g, 61%) as a colorless solid: 1H NMR (300 MHz, CDCl3) δ 9.23 (br s, 1H), 7.47-7.44 (m, 1H), 7.35-7.21 (m, 9H), 7.18-7.11 (m, 2H), 6.90 (s, 1H), 6.83 (dd, J=11.2, 6.9 Hz, 1H), 6.67 (dd, J=11.2, 8.7 Hz, 1H), 6.56-6.51 (m, 1H), 4.13 (br s, 1H); MS (ES+) m/z 426.2 (M−17).

Herkunft & Nachweise