[Synthesis]
Phosphoryl chloride (0.67 mL, 7.35 mmol) was slowly added to a suspension of 5-(ethoxymethyl)pyrimidine-2,4(1H,3H)-dione (0.5 g, 2.94 mmol) in toluene (1 mL) at 0 °C and stirred for 15 min. Subsequently, Hünig base (N,N-diisopropylethylamine, 0.77 mL, 4.41 mmol) was added dropwise to the reaction mixture at 0 °C. The reaction mixture was warmed to 120 °C and stirred for 1 hour. Upon completion of the reaction, the mixture was cooled to room temperature and slowly poured into a pre-cooled two-phase mixture of ethyl acetate and water (1:1, v/v) at 0°C for 45 minutes. Stirring was continued at the same temperature for 1.5 hours. The reaction mixture was extracted with ethyl acetate, the organic layers were combined, washed sequentially with water and saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to give the crude product INT-60 (0.40 g, 65% yield) as a brown liquid. The crude product was further purified by silica gel column chromatography with the eluent of petroleum ether/ethyl acetate (30:1 to 20:1). The product was characterized by 1H NMR (400 MHz, CDCl3): δ 8.67 (s, 1H), 4.56 (s, 2H), 3.66 (q, J=7.2 Hz, 2H), 1.30 (t, J=7.2 Hz, 3H). |