A mixture of 2-[(3-nitrophenyl)methylene]-3-oxobutanoic acid, ethyl ester (16.46 g, 62.6 mmol), o-methylisourea hydrogen sulfate (14.00 g, 81.4 mmol), and sodium bicarbonate (15.8 g, 18.8 mmol) in dimethylformamide (9.4 ml) was heated at 70° C. (oil bath) under argon overnight. The cooled reaction was diluted with water and extracted with ethyl acetate. The organic phase was washed several times with water, washed with saturated sodium chloride, dried (potassium carbonate) and evaporated. The residue was passed through a pad of silica gel, crystallized from isopropyl ether/hexanes and then triturated with 60% isopropyl ether hexanes (50 ml) to give 1,4-dihydro-2-methoxy-6-methyl-4-(3-nitrophenyl)-5-pyrimidinecarboxylic acid, ethyl ester as light yellow crystals (12.32 g), melting point 101°-103° C.
