[CH3:1][NH:2][C:3]([C:5]1[CH:9]=[CH:8][S:7][CH:6]=1)=[O:4].O[CH2:11][NH:12][C:13](=[O:18])[C:14]([F:17])([F:16])[F:15]>S(=O)(=O)(O)O.C(OCC)(=O)C.C(=O)([O-])O.[Na+]>[CH3:1][NH:2][C:3]([C:5]1[CH:9]=[C:8]([CH2:11][NH:12][C:13](=[O:18])[C:14]([F:17])([F:16])[F:15])[S:7][CH:6]=1)=[O:4]To suspension of N-methyl-3-thiophenecarboxamide (1.12 g) (prepared according to J. Org. Chem. (1976), 41(23), 3668-74) in concentrated aqueous sulphuric acid (25 ml) at 0-5° C. was added N-(hydroxymethyl)trifluoroacetamide (1.134 g). The suspension was allowed to warm to 20° C. and stirred for 2 h. The mixture was poured onto ice (150 g) and diluted with ethyl acetate (200 ml). The biphase mixture was diluted with saturated sodium hydrogen carbonate (200 ml) and treated with sodium hydrogen carbonate (21 g). The phases were separated and the organic phase washed with saturated sodium hydrogen carbonate (150 ml×2). The combined aqueous phases were extracted with ethyl acetate (100 ml). The combined organic extracts were concentrated in vacuo. The residue was pre-absorbed onto silica and purified by biotage (90 g) eluting with 1:1 to 0:1 cyclohexane:ethyl acetate to give the title compound as a white solid (0.7129).
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