General procedure for the synthesis of 4-hydroxy-5-iodopyrimidines from 4-hydroxypyrimidines: 10 g of 4(3H)-pyrimidinone was dissolved in 156 mL of acetic acid, and 25.8 g of N-iodosuccinimide was slowly added at 70 °C. The reaction system was then warmed up to 100 °C and the reaction was continuously stirred for 30 min. Upon completion of the reaction, the reaction mixture was cooled to room temperature and then placed in an ice bath to promote crystallization of the product. Upon completion of crystallization, filtration was carried out under reduced pressure. The resulting solid was washed several times with deionized water and finally dried under reduced pressure to afford the target product 4-hydroxy-5-iodopyrimidine (16 g, yield: 67%). The product was characterized by 1H-NMR (300 MHz, DMSO-d6): δ 12.88 (broad peak, 1H), 8.42 (single peak, 1H), 8.17 (single peak, 1H).
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