2,2-Difluoro-1,3-benzodioxol-5-ol

33070-32-5

1211539-82-0

General procedure for the synthesis of 2,2-difluorobenzo[d][1,3]dioxol-5-ol from 2,2-difluoro-5-bromo-1,3-benzodioxole: Under nitrogen atmosphere, 0.97 g (17.22 mmol) of potassium hydroxide, 0.20 g (0.42 mmol) of di-tert-butyl (2',4',6'-triisopropyl-3,4,5,6-tetra methyl-[1,1'-biphenyl]-2-yl)phosphine and 0.09 g (0.10 mmol) of tris(dibenzylideneacetone)dipalladium(0) were added to 5 ml of 1,4-dioxane and 5 ml of aqueous solution containing 2.04 g (8.61 mmol) of 2,2-difluoro-5-bromobenzodioxolane. The reaction mixture was stirred at 100°C for 17 hours. After completion of the reaction, 22 ml of 1 M hydrochloric acid was added followed by ethyl acetate for extraction. The aqueous layer was extracted three times with ethyl acetate and the combined organic layers were washed with saturated aqueous sodium chloride solution, dried over anhydrous sodium sulfate, filtered and the solvent was removed by distillation under reduced pressure. The crude product obtained was purified by silica gel column chromatography (Expanding agent: heptane/ethyl acetate=80/20) to give 1.42 g (Yield: 94.8%) of 2,2-difluoro-5-hydroxybenzodioxolane as a light yellow oil.1H-NMR (300 MHz, CDCl3, δppm): 6.88 (d, 1H, J=8.7Hz), 6.62 (d , 1H, J=2.4Hz), 6.48 (dd, 1H, J=8.7Hz, 2.4Hz).