[CH3:1][S:2]([C:5]1[CH:6]=[C:7]([C:11]2[S:15][C:14]([C:16](=[O:18])[CH3:17])=[CH:13][CH:12]=2)[CH:8]=[CH:9][CH:10]=1)(=[O:4])=[O:3].C[Si]([N-][Si](C)(C)C)(C)C.[Li+].[F:29][C:30]([F:37])([F:36])[C:31](OCC)=[O:32]>C1COCC1>[F:29][C:30]([F:37])([F:36])[C:31](=[O:32])[CH2:17][C:16]([C:14]1[S:15][C:11]([C:7]2[CH:8]=[CH:9][CH:10]=[C:5]([S:2]([CH3:1])(=[O:4])=[O:3])[CH:6]=2)=[CH:12][CH:13]=1)=[O:18]Into a 250 mL flask was weighed 5.42 g (19.3 mmol) of 1-(5-(3-(methylsulfonyl)phenyl)thiophen-2-yl)ethanone and 42 mL of THF. The resulting suspension was stirred and cooled to 0-3° C. in an ice bath and 23 mL of a lithium bis(trimethylsilyl)amide solution (1.0 M in THF) was added. The resulting thick yellow suspension was stirred and allowed to warm to room temperature then ethyl trifluoroacetate (3.46 mL, 29 mmol) was added. After stirring at room temperature overnight the reaction was concentrated in vacuo to remove THF. The residue was washed into a separatory funnel with ethyl acetate and 1 M HCl. The ethyl acetate was separated, washed with brine, dried (MgSO4), and concentrated in vacuo. The resulting amorphous yellow powder was pure enough for further synthetic transformations, yield: 72 g (99%). 1H NMR (400 MHz, DMSO-d6): δ 8.20 (d, J=7 Hz, 1H), 8.08 (t, J=7 Hz, 1H), 7.95 (d, J=4.0 Hz, 1H), 7.89 (d, J=7 Hz, 1H), 7.78 (d, J=4 Hz, 1H), 7.69 (t, J=7 Hz, 1H), 6.22 (broad s, 1H), 3.26 (s, 3H).
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