Synthesis
General procedure for the synthesis of 2-amino-4-methoxypyrimidine from 4-chloro-6-methoxypyrimidin-2-amine: 4-chloro-6-methoxypyrimidin-2-amine (2.00 g, 12.58 mmol) was dissolved in a solvent mixture of ethanol and ethyl acetate (1:1.3, v/v), followed by the addition of N,N-diisopropylethylamine (4.35 mL, 25.2 mmol) and a 10% palladium-carbon catalyst (10 mol%). The reaction mixture was stirred for 14 hours under a hydrogen atmosphere (using a hydrogen balloon to maintain positive hydrogen pressure). The progress of the reaction was monitored by thin layer chromatography (TLC) (unfolding agent ratio 1:1 hexane to ethyl acetate). Upon completion of the reaction, the reaction mixture was flushed with nitrogen and filtered through a bed of diatomaceous earth to remove the palladium-carbon catalyst. The diatomaceous earth bed was washed well with ethyl acetate. The filtrates were combined and dried with anhydrous sodium sulfate. The solvent was removed by evaporation under reduced pressure to give 2-amino-4-methoxypyrimidine as pure product (94% yield). The product did not require further purification and could be used directly in the subsequent reaction.
References
[1] Patent: WO2009/93981, 2009, A1. Location in patent: Page/Page column 104
[2] Patent: WO2008/98058, 2008, A1. Location in patent: Page/Page column 65
[3] Patent: WO2007/84786, 2007, A1. Location in patent: Page/Page column 98-99
[4] ACS Medicinal Chemistry Letters, 2011, vol. 2, # 10, p. 774 - 779
[5] Chemische Berichte, 1903, vol. 36, p. 3383
