反应详情

To a cold (0° C.) solution of NaOEt (0.2 mol) in absolute alcohol (150 mL) was added propionamidine hydrochloride (10.9 g, 0.1 mol) in one portion. A solution of 2-ethoxymethylene-malonic acid diethyl ester (21.6 g, 0.1 mol) in absolute alcohol (60 mL) was added dropwise to the above mixture during 20 minutes. After the addition was completed, the whole mixture was heated to reflux for 2.5 hours, then cooled and poured to ice water. The aqueous solution was acidified to pH 5 with HCl (6 M), extracted with ethyl acetate (4 100 mL). The organic layer was washed with brine and dried over Na2SO4. The solvent was removed under reduced pressure and the residue was re-crystallized with acetonitrile to afford 2-ethyl-6-oxo-1,6-dihydro-pyrimidine-5-carboxylic acid ethyl ester as white crystals (17 g, 86%). 1H NMR(CDCl3) δ 8.71 (s, 1H), 4.37-4.32 (q, 2H), 2.84-2.78 (q, 2H), 1.38-1.34 (m, 6H). MS (ESI) m/e (M+1)+197.2.

1. additionAfter the addition
2. temperaturethe whole mixture was heated
3. temperatureto reflux for 2.5 hours
4. temperaturecooled
5. extractionextracted with ethyl acetate (4 100 mL)
6. washThe organic layer was washed with brine
7. dry with materialdried over Na2SO4
8. customThe solvent was removed under reduced pressure
9. customthe residue was re-crystallized with acetonitrile