A mixture of 3-amino-5-(5-methyl-1H-pyrazol-4-yl) thiophene-2-carboxamide (0.111 g, 0.50 mmol), ethyl 4-oxocyclohexanecarboxylate (0.34 g, 2.00 mmol), MgSO4 (0.120 g, 1.00 mmol), CSA (0.012 g, 0.05 mmol) and DMA (3 mL) was stirred at 100° C. for 1 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, hexane to EtOAc then to 80:20 EtOAc/MeOH). The obtained residue was triturated with EtOAc, and the precipitate was collected by filtration to afford the title compound (96 mg, 51%, a mixture of 3:2 cis/trans isomers, absolute structure not determined) as yellow solid:
