Hydrochloric Acid → Diisopropyl Ether

Participants

Reaction Steps

A solution of 1,4-dihydro-2-methoxy-6-methyl-4-(2,3-dichlorophenyl)-5-pyrimidinecarboxylic acid, 1-methylethyl ester (1.2 g., 3.37 mmole) and pyridine (1.0 ml.) in dichloromethane (10 ml.) under argon is cooled to 0° and treated dropwise with ethyl chloroformate (0.4 ml., 4.04 mmole). After the addition is completed, the cooling bath is removed and the reaction is allowed to stir at room temperature for one hour. The solvent is then stripped off to provide a colorless solid. This crude material is dissolved in methanol (12 ml.) and treated with 2N hydrochloric acid (3 ml.). The reaction is allowed to stir at room temperature overnight precipitating a colorless solid. The solvent is evaporated and the residue is dissolved in ethyl acetate. The resulting solution is washed with water, sodium bicarbonate solution, and brine. After drying over anhydrous magnesium sulfate, the solvent is stripped off and the residue is triturated with isopopyl ether to give 1.12 g. of colorless solid. Recrystallization from dichloromethane--isopropyl ether gives 6-(2,3-dichlorophenyl)-3,6-dihydro-4-methyl-2-oxo-1,5(2H)-pyrimidinedicarboxylic acid, 1-ethyl 5-(1-methylethyl) ester as a colorless solid; m.p. 173°-175°. TLC (silica gel; ethyl acetate: hexanes, 60:40) Rf =0.30.

Provenance & Evidence