Synthesis
General procedure for the synthesis of 4-amino-5-bromopyrimidin-2(1H)-one from 6-aminopyrimidin-2(1H)-one: 6-aminopyrimidin-2(1H)-one (55.6 g, 0.5 mol), N-bromosuccinimide (106.8 g, 0.6 mol) and DMF (150 mL) were added to a reaction flask, cooled to 15°C, and ultrasonicated for reaction under ultrasonic condition for 1 hour. The progress of the reaction was monitored by thin layer chromatography (TLC) and after confirming the complete reaction of the raw materials, it was filtered. The filter cake was washed with distilled water (20 mL×2) and dried to obtain 4-amino-5-bromopyrimidin-2(1H)-one (90.9 g, 95.6% yield).
Purification Methods
5-Bromocytosine is recrystallised from H2O or 50% aqueous EtOH. Alternatively, dissolve ca 3g in conc HCl (10mL) and evaporate to dryness. Dissolve the residual hydrochloride in the minimum volume of warm H2O and make faintly alkaline with aqueous NH3. Collect the crystals and dry them in a vacuum at 100o. [Hilbdert & Jensen J Am Chem Soc 56 134 1934, Beilstein 25 III/IV 3689.]
References
[1] Patent: CN103819412, 2016, B. Location in patent: Paragraph 0023-0025; 0031-0032; 0037; 0038
[2] Synthesis, 2005, # 7, p. 1103 - 1108
[3] Tetrahedron Letters, 1992, vol. 33, # 50, p. 7779 - 7782
[4] Chemistry Letters, 1987, p. 2311 - 2312
[5] Bulletin of the Chemical Society of Japan, 1989, vol. 62, # 11, p. 3750 - 3751
