A mixture of (4E)-6-tert-butyl-4-(methoxymethylene)isoquinoline-1,3(2H,4H)-dione (50 mg, 0.19 mmol), 4-aminomethyl-1-furan-3-yl-1H-pyridin-2-one hydrochloride (43 mg, 0.19 mmol), and triethylamine (150 μL, 1.1 mmol) in N,N-dimethylformamide (2 mL) is stirred overnight at room temperature. The reaction mixture is concentrated under reduced pressure, and the residue is triturated with chloroform to provide (4Z)-6-tert-butyl-4-[({[1-(3-furyl)-2-oxo-1,2-dihydropyridin-4-yl]methyl}amino)methylene]isoquinoline-1,3(2H,4H)-dione as a white solid (34 mg, 43%).
