2-Ethyl-2-thiourea hydrobromide (1.52 g, 8.19 mmol) and (ethoxymethylene)malononitrile (1.0 g, 8.19 mmol) were added to a solution of N,N-diisopropylethylamine (3.57 mL, 20.05 mmol) in ethanol (20 mL). The reaction mixture was stirred at room temperature for 3.5 hours. Upon completion of the reaction, the resulting solid product was collected by filtration and washed with ethanol. Finally, the product was dried under vacuum to afford 4-amino-2-(ethylthio)-5-pyrimidine as a light yellow solid (580 mg, 39% yield).
