Urea → 5-(2-Methoxyphenoxy)-pyrimidine-2,4,6-trione

Participants

Reaction Steps

Sodium (3.2 g; 160 mmol) was dissolved in ethanol (200 ml). Diethyl (2-methoxyphenoxy)malonate (2) (11.2 g; 160 mmol) and urea (2.6 g; 44 mmol) were added to the mixture while being cooled on ice. The mixture was stirred for 4 hours under reflux. After being cooled, ethanol was evaporated, and the residue was dissolved in a small amount of water and made acidic with hydrochloric acid. The mixture was allowed to stand overnight at room temperature. The crystals that precipitated were collected by filtration and dried, to thereby obtain 7.1 g of 5-(2-methoxyphenoxy)-pyrimidine-2,4,6-trione (3). Phosphorus oxychloride (70 ml) and y-collidine (14 ml) were added to this compound and the mixture was stirred for 10 hours under reflux with heat. After phosphorus oxychloride was evaporated, the residue was added to ice-water and the mixture was extracted with ethyl acetate. The reaction mixture was washed with water and dried over anhydrous sodium sulfate, evaporated, and purified by silica gel column chromatography (ethyl acetate: hexane=1:2), to thereby obtain 4.8 g (yield: 39%) of 5-(2-methoxyphenoxy)-2,4,6-trichloropyrimidine (4) as a colorless solid.

Provenance & Evidence