反应详情

3,5-Difluorobenzoic acid (25 g, 0.158 mol) was dissolved in DCM (150 mL) and dioxane (50 mL). The mixture was transferred into a stainless steel autoclave. Concentrated sulfuric acid (3.6 mL) was added, followed by isobutene (100 mL). The mixture was kept in the autoclave for 5 days. Excess isobutene and the solvents were removed under reduced pressure, the mixture diluted with EtOAc and washed with water, saturated aqueous sodium hydrogen carbonate and brine. Drying and evaporation gave a dark-yellow oil, which was purified by kugelrohr distillation (80–100° C., 1.0 mbar) to give tert-butyl-3,5-difluorobenzoate (27.51, g, 81% ) as a colorless solid.

1. customExcess isobutene and the solvents were removed under reduced pressure
2. additionthe mixture diluted with EtOAc
3. washwashed with water, saturated aqueous sodium hydrogen carbonate and brine
4. customDrying
5. customevaporation
6. customgave a dark-yellow oil, which
7. distillationwas purified by kugelrohr distillation (80–100° C., 1.0 mbar)