Cyclohexene → 4-{[(S)-8-fluoro-6-methylphenanthridin-5(6H)-yl]sulfonyl}phenol

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Reaction Steps

(S)-8-Fluoro-5-(4-methoxy-benzenesulfonyl)-6-methyl-5,6-dihydrophenanthridine (1.26 g, 3.29 mmol) was suspended in cyclohexene (6.0 mL, 59 mmol). Boron tribromide (20 mL, 1.0 M solution in dichloromethane) was added dropwise at room temperature. The solution was stirred for 20 hours. A solution of saturated, aqueous sodium bicarbonate (300 mL) was added dropwise and then the mixture was extracted with dichloromethane (6×20 mL). The combined organic layers were dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo. The crude material was purified by silica gel flash chromatography (1:19 to 1:4 ethyl acetate:hexane) and then recrystallization (dichloromethane-hexane) to afford the title compound as white crystals (1.1 g, 90%), m.p. 193° C.

Provenance & Evidence