反应详情

To a solution of 22 g of methyl-4-bromoacetoacetate in 200 ml benzene is added 14.4 g of 1,1-dimethylbutylurea and 100 mg of p-toluene sulfonic acid. The solution is heated at reflux under nitrogen for four hours with water removal. At the end of this period the solution is cooled and concentrated. The residual material is chromatographed on 400 g of silicic acid. Elution with a solution of benzene (60%), ethyl acetate (30%) and methanol (10%) gives crystalline material. Recrystallization of this material from ethyl acetate gives 1.8 g of 1-(1,1-dimethylbutyl)-3-(2,5-dihydro-5-oxo-3-furyl)urea, m.p. 130°-132° C.

1. temperatureThe solution is heated
2. temperatureAt the end of this period the solution is cooled
3. concentrationconcentrated
4. customThe residual material is chromatographed on 400 g of silicic acid
5. washElution with a solution of benzene (60%), ethyl acetate (30%) and methanol (10%)
6. customgives crystalline material
7. customRecrystallization of this material from ethyl acetate