反应详情

To a solution of 2,2,6,7-tetramethyl-1-benzofuran-3 (2H)-one obtained in Reference Example 41 (5.20 g, 27.3 mmol) in anhydrous trifluoroacetic acid (50 mL) and chloroform (5 mL) was added ammonium nitrate (2.10 g, 32.8 mmol) at 0° C., and the mixture was stirred at the same temperature for 2 hours, and then concentrated under reduced pressure. Water was added to the residue, which was extracted with ethyl acetate. The extract was washed with water and a saturated sodium hydrogen carbonate solution, and then was dried over anhydrous sodium sulfate. The solvent was distilled off under reduced pressure to obtain a residue, which was purified by silica gel column chromatography (hexane:ethyl acetate=50:1) to obtain 5.40 g (yield 84%) of the title compound. Melting point: 131-132° C. (ethyl acetate-hexane).

1. concentrationconcentrated under reduced pressure
2. additionWater was added to the residue, which
3. extractionwas extracted with ethyl acetate
4. washThe extract was washed with water
5. dry with materiala saturated sodium hydrogen carbonate solution, and then was dried over anhydrous sodium sulfate
6. distillationThe solvent was distilled off under reduced pressure
7. customto obtain a residue, which
8. customwas purified by silica gel column chromatography (hexane:ethyl acetate=50:1)