2,3-Dihydro-1,4-benzodioxin-5-ol → 1-(diphenylmethyl)-3-hydroxy-3-(5-hydroxy-2,3-dihydro-1,4-benzodioxin-6-yl)-1,3-dihydro-2H-indol-2-one

Participants

Reaction Conditions

Reaction Steps

To a solution of 2,3-dihydro-1,4-benzodioxin-5-ol (3.60 g, 23.7 mmol) in anhydrous tetrahydrofuran (80 mL) at 0° C. was added isopropylmagnesium chloride (11.8 mL, 2 M solution in tetrahydrofuran, 23.7 mmol). The mixture was stirred at 0° C. for 45 min, concentrated in vacuo, and 1,2-dichloroethane (60 mL) was added. The mixture was cooled to 0° C. and a solution of 1-benzhydrylindoline-2,3-dione (4.94 g, 15.8 mmol) in 1,2-dichloroethane (70 mL) was added. The reaction mixture was allowed to warm to ambient temperature and stirred for 60 h, and heated to 83° C. and stirred for 3.5 h. The reaction mixture was allowed to cool to ambient temperature, concentrated in vacuo and saturated aqueous ammonium chloride (250 mL) was added. The mixture was extracted with ethyl acetate (250 mL followed by 2×100 mL). The organic phase was washed with water (150 mL) and brine (150 mL), dried over sodium sulfate and filtered. The filtrate was concentrated in vacuo. The residue was taken up in ethyl acetate and a solid was precipitated by the addition of hexanes to afford 1-(diphenylmethyl)-3-hydroxy-3-(5-hydroxy-2,3-dihydro-1,4-benzodioxin-6-yl)-1,3-dihydro-2H-indol-2-one (5.10 g, 69%) as a colorless solid: 1H NMR (300 MHz, CDCl3) δ9.14 (s, 1H), 7.43-7.30 (m, 9H), 7.22 (d, J=8.7 Hz, 1H), 6.97-6.79 (m, 3H), 6.52 (s, 1H), 6.44 (d, J=8.7 Hz, 1H) 6.26 (d, J=7.8 Hz, 1H), 4.22 (s, 4H).

Provenance & Evidence