反应详情

To a solution of 6-hydroxy-1,3-benzoxazol-2(3H)-one (4.9 g, 32 mmol) in anhydrous N,N-dimethylformamide (40 mL) was added imidazole (2.6 g, 39 mmol) and chloro-tert-butyldimethylsilane (5.4 g, 35 mmol). The reaction mixture was stirred at ambient temperature for 16 h and diluted with ethyl acetate (100 mL). The resultant suspension was filtered and the filtrate was concentrated in vacuo. The residue was taken up in anhydrous N,N-dimethylformamide (50 mL) and cooled to 0° C. To this solution was added sodium hydride (1.6 g, 60% dispersion in mineral oil, 39 mmol) and the reaction mixture was stirred at 0° C. for 15 min. Iodomethane (6.1 mL, 97 mmol) was added and the reaction mixture was stirred at ambient temperature for 16 h. The reaction mixture was concentrated in vacuo and the residue was taken up in water (100 mL) and ethyl acetate (100 mL). The phases were separated and the aqueous phase was extracted with ethyl acetate (2×100 mL). The combined organic solution was washed with water (2×100 mL) and brine (100 mL), dried over anhydrous sodium sulfate, filtered and concentrated in vacuo. The crude product was purified by column chromatography with hexanes/ethyl acetate (5/1) to afford 6-{[tert-butyl(dimethyl)silyl]oxy}-3-methyl-1,3-benzoxazol-2(3H)-one (6.55 g, 72%) as a colorless solid: 1H NMR (300 MHz, CDCl3) δ6.79-6.72 (m, 2H), 6.69-6.64 (m, 1H), 3.36 (s, 3H), 0.98 (s, 9H), 0.17 (s, 6H).

1. filtrationThe resultant suspension was filtered
2. concentrationthe filtrate was concentrated in vacuo
3. temperaturecooled to 0° C
4. stirringthe reaction mixture was stirred at 0° C. for 15 min
5. stirringthe reaction mixture was stirred at ambient temperature for 16 h
6. concentrationThe reaction mixture was concentrated in vacuo
7. customThe phases were separated
8. extractionthe aqueous phase was extracted with ethyl acetate (2×100 mL)
9. washThe combined organic solution was washed with water (2×100 mL) and brine (100 mL)
10. dry with materialdried over anhydrous sodium sulfate
11. filtrationfiltered
12. concentrationconcentrated in vacuo
13. customThe crude product was purified by column chromatography with hexanes/ethyl acetate (5/1)