反应详情

To a hot (60° C.) solution of propionamidine hydrochloride prepared in step 2 (54.3 g, 0.5 mol) and propynoic acid ethyl ester (53.9 g, 0.55 mol) in absolute alcohol (1 L) was added dropwise a solution of KOH (70 g, 80%, 1 mol) in absolute alcohol (300 mL) during 3 hours. The temperature was kept between 60° C. and 70° C. during the addition. The solvent was removed in vacuo and the residue was dissolved in water. The aqueous solution was acidified to pH 5 with HCl (6 M), extracted with ethyl acetate for at least 15 times. The organic layer was dried over Na2SO4 and then filtered. The filtrate was evaporated under reduced pressure and the residue was recrystallized with acetonitrile to afford 2-ethyl-3H-pyrimidin-4-one as light yellow crystals (14 g, 23%).

1. additionThe temperature was kept between 60° C. and 70° C. during the addition
2. customThe solvent was removed in vacuo
3. dissolutionthe residue was dissolved in water
4. extractionextracted with ethyl acetate for at least 15 times
5. dry with materialThe organic layer was dried over Na2SO4
6. filtrationfiltered
7. customThe filtrate was evaporated under reduced pressure
8. customthe residue was recrystallized with acetonitrile