Ammonium Chloride → 1-(diphenylmethyl)-3-(5-fluoro-7-hydroxy-2,3-dihydro-1,4-benzodioxin-6-yl)-3-hydroxy-1,3-dihydro-2H-indol-2-one

Participants

Reaction Steps

A 100 mL round-bottom flask was charged with 8-fluoro-2,3-dihydrobenzo[b][1,4]dioxin-6-ol (6.4 g, 37 mmol) and tetrahydrofuran (60 mL). A 2 M solution of isopropylmagnesium chloride in tetrahydrofuran (20.0 mL, 40.0 mmol) was added at 5° C. and the reaction mixture was stirred for 15 min. The reaction mixture was concentrated in vacuo and dichloromethane (60 mL) was added, followed by a solution of 1-(diphenylmethyl)-1H-indole-2,3-dione (10.9 g, 35.0 mmol) in dichloromethane (60 mL). The reaction mixture was heated at reflux for 5 h, allowed to cool to ambient temperature and stirred for a further 16 h. Saturated aqueous ammonium chloride (30 mL) was added and the phases were separated. The organic phase was dried over magnesium sulfate, filtered and concentrated in vacuo. Trituration of the residue in methanol (30 mL) afforded 1-(diphenylmethyl)-3-(5-fluoro-7-hydroxy-2,3-dihydro-1,4-benzodioxin-6-yl)-3-hydroxy-1,3-dihydro-2H-indol-2-one (10.8 g, 64%) as an off-white solid: MS (ES+) m/z 506.0 (M+23).

Provenance & Evidence