[CH3:1][O:2][N:3]([CH3:11])[C:4]([C:6]1[CH:10]=[CH:9][S:8][CH:7]=1)=[O:5].[Cl:12]N1C(=O)CCC1=O>CC(O)=O>[Cl:12][C:9]1[S:8][CH:7]=[C:6]([C:4]([N:3]([O:2][CH3:1])[CH3:11])=[O:5])[CH:10]=1To a stirred solution of N-methoxy-N-methylthiophene-3-carboxamide (5.0 g, 1.0 eq, prepared from Example 12 step A) in 50 mL CH3COOH was added N-chlorosuccinimide (3.88 g, 1.0 eq). The mixture was then reflux at 120° C. for 4 h. After quenching with water, the mixture was extracted with ethyl acetate. The extract was washed with brine, dried, concentrated, and purified by column chromatography to get 3.0 g desired product (40% yield).
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