Bromotrichloromethane → Malonic acid, bromoethyl-, diethyl ester

In a 10 mL round-bottom flask, 1.88 g of diethyl ethylmalonate (10 mmol), 2.18 g of bromotrichloromethane (11 mmol), 79 mg of tetra-n-butylammonium fluoride trihydrate (0.25 mmol), and 69 mg of potassium carbonate (0.5 mmol) were stirred at 24° C. for 1 h. An exothermic reaction caused the temperature of the mixture to rise to 40° C. After filtration of the solids, the solution was found to contain 2.5 g (95% yield) of diethyl α-bromo-α-ethylmalonate.