[O-]CC.[Na+].[Na].[F:6][C:7]1[CH:8]=[CH:9][C:10]([C:17](=[O:23])[CH2:18][S:19]([CH3:22])(=[O:21])=[O:20])=[C:11]([CH:16]=1)[N:12]([CH3:15])[CH:13]=O.Cl>C(O)C>[F:6][C:7]1[CH:16]=[C:11]2[C:10]([C:17](=[O:23])[C:18]([S:19]([CH3:22])(=[O:21])=[O:20])=[CH:13][N:12]2[CH3:15])=[CH:9][CH:8]=1A solution of sodium ethoxide in ethanol, prepared from sodium metal (2.3 g) and absolute ethanol (50 ml), was added dropwise over 5 minutes to a solution of 5'-fluoro-N-methyl-2'-methylsulphonylacetylformanilide (2.7 g), prepared in a similar manner to that described in Example 11, in absolute ethanol (10 ml) at ambient temperature. The mixture was stirred at this temperature for 30 minutes then added to hydrochloric acid (1M; 100 ml), keeping the temperature below 30°. The mixture was extracted with dichloromethane (2×150 ml). The extracts were combined, dried (magnesium sulphate) and evaporated in vacuo to give the crude product (2.5 g). The crude product was crystallised from industrial methylated spirit to give 7-fluoro-1-methyl-3-methylsulphonyl-4-quinolone, m.p. 221°-222.5° (2.0 g). The product was heated to 90° with grinding to give 7-fluoro-1-methyl-3-methylsulphonyl-4-quinolone, m.p. 234°-235° (2.0 g).
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