To a solution (1.25 M) of diethyl acetamidomalonate (6.79 g, 31.25 mmol) in N-methyl-2-pyrrolidone (25 mL) was added 60% sodium hydride (1.25 g, 31.25 mmol), and the mixture was stirred at room temperature for 1 hr. Diphenylmethylene chloride (4.45 mL, 25.0 mmol) and potassium iodide (4.15 g, 25 mmol) were added, and the mixture was stirred at 50° C. for 7 hrs. After completion of the reaction, toluene (75 mL) and water (31.5 mL) were added to the reaction mixture, and the mixture was partitioned. The organic layer was washed twice with water (31.5 mL) and concentrated. Ethanol (31.5 mL) and 2M aqueous sodium hydroxide solution (37.5 mL) were added to the concentrated solution, and the mixture was stirred at 80° C. for 11 hrs and allowed to cool to 25° C. Toluene (9 mL) was added and the mixture was partitioned. The aqueous layer was concentrated to a half volume and adjusted to pH 1.1 with concentrated hydrochloric acid, which resulted in the precipitation of white crystals. The crystals were collected by filtration and dried under vacuum to give the title compound (5.0 g).
