反应详情

70 g of 2,3-dihydro-2,2-dimethyl-6-hydroxy-4H-1,3-benzoxazin-4-one in 400 ml of acetonitrile with 100 g of potassium carbonate and 32 ml of chloroacetone are stirred under reflux for 30 hours. After the addition of a further 3.2 ml of chloroacetone, the reaction mixture is refluxed for a further 15-20 hours. The reaction mixture is filtered whilst still warm; the residue is thoroughly washed with acetone, and the combined filtrate is concentrated by evaporation. The crystalline residue is recrystallised from toluene and yields 2,3-dihydro-2,2-dimethyl-6-(2-oxopropoxy)-4H-1,3-benzoxazin-4-one, m.p. 125°-126°.

1. temperatureunder reflux for 30 hours
2. temperaturethe reaction mixture is refluxed for a further 15-20 hours
3. filtrationThe reaction mixture is filtered
4. temperaturewhilst still warm
5. washthe residue is thoroughly washed with acetone
6. concentrationthe combined filtrate is concentrated by evaporation
7. customThe crystalline residue is recrystallised from toluene