反应详情

A solution of 2.5 g of 3,4-dimethoxy-5-nitrobenzoyl chloride in 10 ml of absolute tetrahydrofuran is treated with 1.1 ml of ethyl isocyanoacetate and subsequently with a solution of 3.0 ml of triethylamine in 10 ml of tetrahydrofuran and stirred at room temperature for 48 hours. After distillation of the solvent, the residue is extracted with ethyl acetate/water. The crude product obtained after evaporation is chromatographed on a 20-fold amount of silica gel with ethyl acetate. After recrystallization from ethyl acetate/hexane there is obtained ethyl 5-(3,4-dimethoxy-5-nitrophenyl)-4-oxazole-carboxylate in the form of yellow crystals of m.p. 109°-110°.

1. distillationAfter distillation of the solvent
2. extractionthe residue is extracted with ethyl acetate/water
3. customThe crude product obtained
4. customafter evaporation
5. customis chromatographed on a 20-fold amount of silica gel with ethyl acetate
6. customAfter recrystallization from ethyl acetate/hexane there