Thymine → 2-(5-Methyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-yl)acetic acid

This procedure is different from the literature synthesis, but is easier, gives higher yields, and leaves no unreacted thymine in the product. To a suspension of thymine (3, 40 g, 0.317 mol) and potassium carbonate (87.7 g, 0.634 mmol) in DMF (900 mL) was added methyl bromoacetate (30 mL, 0.317 mmol). The mixture was stirred vigorously overnight under nitrogen. The mixture was filtered and evaporated to dryness, in vacuo. The solid residue was treated with water (300 mL) and 4 N hydrochloric acid (12 mL), stirred for 15 minutes at 0° C., filtered, and washed with water (2×75 mL). The precipitate was treated with water (120 mL) and 2 N sodium hydroxide (60 mL), and was refluxed for 10 minutes. The mixture was cooled to 0° C., filtered, and title compound was precipitated by the addition of 4 N hydrochloric acid (70 mL). The yield after drying, in vacuo over sicapent was 37.1 g (64%). 1H-NMR: (90 MHz; DMSO-d6): 11.33 ppm (s, 1H, NH); 7.49 (d, J=0.92 Hz, 1H, ArH); 4.38 (s, 2H, CH2); 1.76 (d, J=0.92 Hz, T-CH).