[F:1][CH:2]([F:8])[C:3]([O:5]CC)=O.C[O-].[Na+].[C:12]([C:15]1[S:16][CH:17]=[CH:18][CH:19]=1)(=[O:14])[CH3:13].Cl>CCOCC>[F:8][CH:2]([F:1])[C:3](=[O:5])[CH2:13][C:12]([C:15]1[S:16][CH:17]=[CH:18][CH:19]=1)=[O:14]Ethyl difluoroacetate (1.84 g, 14.8 mmol) was placed in a 100 mL round bottom flask and dissolved in ether (5 mL). To the stirred solution was added 25 weight % sodium methoxide (3.39 g, 15.7 mmol) followed by 2-acetylthiophene (1.72 g, 13.6 mmol). The reaction was stirred at room temperature overnight (15.67 hours), then treated with 3N HCl (8 mL). The organic layer was collected and washed with brine, dried over MgSO4, concentrated in vacuo, and recrystallized from methylene chloride/isooctane to give a brown solid (1.38 g, mp 78°-80° C., 50%). 1H NMR (CDCl3) 300 MHz 14.90 (br s, 1H), 7.80 (d, J=4.0 Hz, 1H), 7.71 (d, J=3.8 Hz, 1H), 7.19 (m, 1H), 6.41 (s, 1H), 6.04 (t, J=54.2 Hz, 1H); 19F NMR (CDCl3) 300 MHz: -126 98 (d); M+204.
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