2908-71-6

769-82-4

2908-71-6

S4. 100 g of the ring-closing product (cas:769-82-4) was placed in a 1 liter wide-mouth reaction flask and 500 mL of 33% hydrobromic/acetic acid solution was added. The reaction system was rapidly heated to 100 °C and maintained at this temperature for 8-16 h. The endpoint of the reaction was monitored by thin layer chromatography (TLC). Upon completion of the reaction, 20 g of acidic activated carbon was added to the reaction mixture and stirred for 30 min before thermal filtration. The filtrate was concentrated to dryness under reduced pressure. Subsequently, 30 mL of anhydrous ethanol was added and filtered after cooling to precipitate crystals. Finally, 1.49 g of 5-(bromomethyl)-2-methylpyrimidin-4-amine hydrobromide was obtained by drying in 87% yield.