Synthesis
A mixture of 2-chloro-5-nitropyrimidin-4-amine (1.0 g, 5.7 mmol) and SnCl2·2H2O (5.2 g, 22.9 mmol) in EtOH (55 mL) under N2 was heated to 80 °C and stirred for two hours. The mixture was then concentrated under reduced pressure. EtOAc and Celite were added to the residue, and the mixture was basified with saturated Na2CO3 (aq.) to pH 9- 10. The mixture was filtered through a pad of Celite and washed with EtOAc. The organic layer was separated, washed with brine, dried (Na2SO4), and concentrated in a vacuum. The residue was purified on ISCO (20 g silica gel column, EtOAc/hexanes 0~100 per cent) to give 2-Chloro-4,5-diaminopyrimidine (0.41 g 49 per cent).
