A mixture of 3-amino-4-bromo-5-(1H-pyrazol-4-yl)thiophene-2-carboxamide (90 mg, 0.313 mmol), 4,4,4-trifluorobutan-2-one (395 mg, 3.13 mmol), CSA (7.28 mg, 0.031 mmol), MgSO4 (37.7 mg, 0.313 mmol) and DMA (2 mL) was microwave-irradiated at 150° C. for 3 h. The mixture was poured into saturated aqueous NaHCO3 and extracted with EtOAc, and the extract was dried over MgSO4, filtered and concentrated under reduced pressure. The residue was purified by column chromatography (Purif, silica gel, 95:5 hexane/EtOAc to EtOAc). The obtained solid was triturated with EtOAc, and the precipitate was collected by filtration to afford the title compound (29.2 mg, 24%) as a white solid:
