4-Methoxybenzenesulfonyl chloride → (S)-8-Fluoro-5-(4-methoxy-benzenesulfonyl)-6-methyl-5,6-dihydrophenanthridine

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Reaction Steps

A solution of 8-fluoro-6-methylphenanthridine (0.5 g, 2.4 mmol) and 4-methoxybenzenesulfonyl chloride (0.514 g, 2.49 mmol) in dichloromethane (5 mL) was added to a solution of borane-methyl sulfide (0.142 mL, 1.42 mmol, 10 M solution in methyl sulfide) and (R)-2-methyl-CBS-oxazaborolidine (0.47 mL, 0.4734 mmol, 1.0 M solution in toluene) in dry dichloromethane (6 mL) over the course of three hours at room temperature. The reaction mixture was stirred for twelve hours and then a solution of aqueous sodium hydroxide (10 mL, 1 N) was added. The aqueous layer was extracted with dichloromethane (3×). The organic layers were combined, washed with a solution of saturated, aqueous sodium chloride, and dried over anhydrous sodium sulfate. The organic solvent was removed in vacuo to yield the crude product as an orange solid. The crude product was purified by chromatography on silica gel (1:10 ethyl acetate:hexane) to afford the title compound as a white solid (0.489 g, 1.28 mmol, 54% ).

Provenance & Evidence