Ammonia → 5-Pyrimidinecarboxaldehyde, 4-amino-6-chloro-

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A solution of 7 M NH3 in MeOH (265 mL, 1.855 mol, 2.0 equiv) was added over 1.25 h to a solution of 4,6-dichloropyrimidine-5-carbaldehyde (163.7 g, 0.9301 mol) in toluene (3 L) at ambient temperature. The reaction temperature slowly increased from 20 to 26° C. and a yellow suspension formed. Mild cooling was applied to maintain the reaction temperature at below 26° C. The suspension was stirred at ambient temperature for 3.5 h before the solids were collected by filtration. The solids were washed with EtOAc (1 L). The filtrate was concentrated under reduced pressure, and the solids were triturated with toluene and n-heptane (2:1 v/v, 600 mL), filtered and dried to give 71.1 g of 4-amino-6-chloropyrimidine-5-carbaldehyde as a yellow solid. The original solid filtered from the reaction mixture contained additional amount of 4-amino-6-chloropyrimidine-5-carbaldehyde. The product was extracted from the filtered solid by stirring in EtOAc (1.25 L) for 1.5 h, filtering, then stirring in THF (750 mL) for 1 h and again filtering. Both EtOAc and THF filtrates were concentrated under reduced pressure, and the resulting solids were triturated with toluene and n-heptane (2:1 v/v, 450 mL), filtered and dried to give an additional 44.1 g of 4-amino-6-chloropyrimidine-5-carbaldehyde as a yellow solid. The combined yield of 4-amino-6-chloropyrimidine-5-carbaldehyde (115.2 g, 146.5 g theoretical) was 78.6%. 1H NMR (300 MHz, DMSO-d6) δ 10.23 (s, 1H), 8.71 (bs, 1H), 8.55 (bs, 1H), 8.39 (s, 1H) ppm; C5H4ClN3O (MW, 157.56), LCMS (EI) m/e 158 (M++H).

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