反应详情

1-Methyl-3-(4'-fluorophenyl)-3-hydroxyurea (10.0 g; 0.054 moles) was dissolved in dioxane (80 ml.) and mixed with a 2 N aqueous sodium hydroxide (32 ml; 0.064 mole). Ethyl chloroformate (5.7 ml; 0.06 mole) was added dropwise to the mixture at 10°-15° C. with stirring and the stirring continued for 1/2 hour after the addition was completed. The product which precipitated as formed was removed by filtration, washed with water and dried. The product was recrystallized from methanol and dried under vacuum to yield 2-(4'-fluorophenyl)-4-methyl-1,2,4-oxadiazolidine-3,5-dione as a solid melting 97°-99° C. and having the following elemental analysis as calculated for C9H7FN2O3 :

1. additionafter the addition
2. customThe product which precipitated
3. customas formed
4. customwas removed by filtration
5. washwashed with water
6. customdried
7. customThe product was recrystallized from methanol
8. customdried under vacuum