1546-78-7

6313-33-3

372-31-6

1546-78-7

Ethyl trifluoroacetoacetate (0.16 mL, 1.0 eq.) and DBU (0.19 mL, 1.2 eq.) were added to a three-necked flask, followed by the addition of anhydrous ethanol (10 mL) to dissolve the reactants. An ethanol solution of formamidine hydrochloride (0.09 g formamidine hydrochloride dissolved in 2 mL of ethanol, 1.05 equiv. of formamidine hydrochloride) was prepared and added to the reaction system. The reaction temperature was adjusted to 70-80 °C and maintained for 3-5 hours, during which the progress of the reaction was monitored by TLC. After completion of the reaction, the solvent was removed by distillation under reduced pressure. The residue was diluted with water (20 mL) and the pH was adjusted to 6-7 with 1 mol/L hydrochloric acid.Subsequently, the aqueous phase was extracted with ethyl acetate (3 × 8 mL), the organic phases were combined and dried with anhydrous sodium sulfate. After filtration, the solvent was removed by vacuum distillation to give a light yellow solid. The solid was washed with petroleum ether (5 mL), filtered and the filter cake was washed with petroleum ether. Finally, the product was dried in an oven at 55 °C for 2 h to give a light yellow flaky solid in 96% yield.