[S:1]1[CH:5]=[CH:4][CH:3]=[C:2]1[CH2:6][C:7]([OH:9])=O.CN(C=O)C.C(N1C=CN=C1)(N1C=CN=C1)=O.Cl.[CH3:28][NH:29][O:30][CH3:31]>[Cl-].[NH4+]>[CH3:31][O:30][N:29]([CH3:28])[C:7](=[O:9])[CH2:6][C:2]1[S:1][CH:5]=[CH:4][CH:3]=1A 25 mL RB flask with a stirring bar was charged with 2-thiopheneacetic acid (2.84 g, 2 mmol), followed by anhydrous DMF (10 mL). 1,1′-Carbonyldiimidazole (3.24 g, 2 mmol) was added in one portion, giving rise to significant gas evolution. The mixture was warmed to 40° C. After 30 min, N,O-dimethylhydroxyamine hydrochloride (2.14 g, 2.2 mmol) was introduced in one portion. The mixture was allowed to stir at 23° C. for 30 min. before being diluted with sat. ammonium chloride solution (100 mL) and extracted twice with 1:1 ethyl acetate/hexanes (100 mL). The crude mixture was purified by column chromatography over silica gel (0-25% ethyl acetate/hexanes) to give N-methoxy-N-methyl-2-(2-thienyl)acetamide (1-1). 1H NMR (CDCl3, ppm) δ 7.20 (m, 1H), 6.96 (m, 2H), 3.91 (s, 2H), 3.70 (s, 3H), 3.25 (s, 3H).
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