To a mixture of the carboxylic acid 55 (1.04 g, 1.5 mmol), 2-amino-1-(thiophen-3yl)ethanone hydrochloride (533 mg, 3.0 mmol), EDCI (575 mg, 3.0 mmol), and HOBt (507 mg, 3.75 mmol) in DMF (10 mL) was added NMM (0.83 mL, 7.5 mmol). The resulting mixture was stirred at room temperature for 15 h. The reaction mixture was poured into a HCl solution (1.0 M, 50 mL), and extracted with EtOAc. The organic phase was dried over anhydrous MgSO4, filtered and evaporated under vacuum. The residue was further purified by silica column chromatography to provide the titled amide compound (529 mg, 0.65 mmol, 43%).
