反应详情

温度

-40 °C

A solution of benzofuran (4.24 g, 36 mmol) in dry THF (20 mL) under argon was cooled to −78° C. n-Butyllithium (22.5 mL, 36 mmol, 1.6M in hexanes) was added dropwise such that an internal temperature below −65° C. was maintained. The reaction was allowed to stir at −78° C. for two hours during which time 2-lithiobenzofuran precipitated as a white solid. The suspension of 2-lithiobenzofuran was added dropwise to a cooled (−78° C.) solution of [1(S)-(Methoxy-methyl-carbamoyl)-2,2-dimethylpropyl]-carbamic acid-tert-butyl ester (3.34 g, 12 mmol) in THF (30 mL) via cannula such that an internal temperature of below −65° C. was maintained. The yellow solution was allowed to stir at −70° C. for 30 minutes and −40° C. for a further 3 hours. The reaction was quenched by addition of saturated ammonium chloride solution (200 mL). The aqueous phase was extracted with ethyl acetate (3×150 mL) and the combined organic extracts washed with brine (2×200 mL), dried over magnesium sulphate, filtered and the solvents removed in vacuo to give a crude yellow oil. Purification by column chromatography (SiO2, 10% ethyl acetate in hexanes) gave the title compound as a yellow solid (3.45 g, 87%).

1. additionwas added dropwise such that an internal temperature below −65° C.
2. temperaturewas maintained
3. customprecipitated as a white solid
4. additionThe suspension of 2-lithiobenzofuran
5. additionwas added dropwise to
6. temperaturewas maintained
7. customThe reaction was quenched by addition of saturated ammonium chloride solution (200 mL)
8. extractionThe aqueous phase was extracted with ethyl acetate (3×150 mL)
9. washthe combined organic extracts washed with brine (2×200 mL)
10. dry with materialdried over magnesium sulphate
11. filtrationfiltered
12. customthe solvents removed in vacuo
13. customto give a crude yellow oil
14. customPurification by column chromatography (SiO2, 10% ethyl acetate in hexanes)