m-Chloroperbenzoic acid → 3-Dichloromethylsulfinyl-7-fluoro-1-methyl-4-quinolone

Participants

Reaction Steps

The crude product (2) was used in the second stage. To a stirred solution of 673 mg (2.873 mmol) of compound (2) in 80 ml DCM, ˜80%, m-chloroperbenzoic acid (MCPBA) (620 mg, 2.873 mmol) was added in a few portions over a period of 1 minute at 0° C. The stirred mixture was allowed to warm to room temperature, was stirred for one hour and then an additional 18 mg of MCPBA was added to complete the transformation. After 30 minutes stirring at room temperature the reaction solution was washed with 15 ml of 5% aqueous sodium carbonate. The aqueous layer was extracted two times with 60 ml of DCM each and the combined DCM solutions were dried over sodium sulfate and concentrated. The residue 660 mg was chromatographed on silica gel with hexane-ethyl acetate (gradient 1:1, 2:3, 1:2) to give 358 mg (50% yield) of racemic 7-fluoro-3-fluoromethylsulfinyl-1-methyl-4-quinolone (3) (monofluoroflosequinan) as a white solid. 1H NMR, CDCl3; δ=3.93 s, 3H, N—CH3; 5.75, 5.73, 5.59, 5.56, 5.46, 5.43, 5.30, 5.27 (8 lines, AB part of ABX), 2H, CH2; 7.18-7.30 m, 2H, H at C8 & C6; 7.98 s, 1H, H at C2; 8.44 dd, 1H, J=9.0 & 6.3 Hz, H at C5.

Provenance & Evidence