Step 1: 2-Amino-6-chloropurine (2 g) was added to acetic anhydride (25 mL) preheated to 180 °C and the reaction was heated to reflux overnight. Upon completion of the reaction, the mixture was cooled to room temperature. The precipitate was precipitated by the addition of ether and the solid product was collected by filtration and dried. The crude product was purified by reversed-phase fast column chromatography (elution gradient: 0-60% aqueous methanol) to afford N-(6-chloro-9H-purin-2-yl)acetamide (450 mg, 17% yield) as a white solid. m/z 212 ([M+H]+) was obtained by LC-MS analysis.
