Step 1. Ethyl 4-chloro-2-(methylthio)pyrimidine-5-carboxylate (100 g, 0.43 mol), tetrahydrofuran (THF, 500 mL) and triethylamine (TEA, 186 mL, 1.29 mol) were added sequentially to a 2L three-neck flask. 28% aqueous ammonium hydroxide solution (400mL) was added in batches under stirring and the reaction temperature was controlled to be below 30°C. After 2 hrs of reaction, water (1000 mL) was added and THF was removed by vacuum distillation.The reaction mixture was filtered and the solid product was collected and dried under vacuum at 50 °C to afford ethyl 4-amino-2-(methylthio)pyrimidine-5-carboxylate as a white solid (90 g, 99% yield). The product was analyzed by LC/MS showing m/z = 213.9 [M+H]+; 1H-NMR (DMSO-d6, 400MHz) δ 8.57 (s, 1H), 8.03 (br, 1H), 7.65 (br, 1H), 4.27 (q, J = 7.5Hz, 2H), 2.46 (s, 3H), 1.29 (t, J = 7.2Hz , 3H).
