A mixture of 3-amino-5-(5-methyl-1H-pyrazol-4-yl) thiophene-2-carboxamide (111 mg, 0.50 mmol), tert-butyl (4-oxocyclohexyl)carbamate (320 mg, 1.50 mmol), MgSO4 (120 mg, 1.00 mmol), CSA (11.6 mg, 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 residue obtained was dissolved with small amount of MeOH/EtOAc and added dropwise to a stirred solution of hexane (100 mL). The precipitate was collected by filtration to afford the title compound (122 mg, 58%, a mixture of 11:9 cis/trans isomers, absolute structure not determined) as yellow solid:
