反应详情

温度

-20 °C

A solution of 5-bromo-7-tert-butyl-3,3-dimethyl-2,3-dihydrobenzo[b]furan (12.4 g, 44.0 mmol) in freshly distilled THF (44 mL) is cooled to -78° C. under Ar, and a solution of n-butyl lithium (2.5M in hexane; 15.0 mL, 37.5 mmol) is added dropwise via syringe. A slight exotherm is apparent, and a milky suspension results. The suspension is allowed to warm to -20° C., and then is cooled to -50° C. To the resulting suspension is added a large excess of freshly pulverized solid CO2. The resulting mixture is allowed to warm to 0° C. After 1 h, the mixture is partitioned between 0.1N NaOH (40 mL) and hexane (3×30 mL). The hexane layer is dried (MgSO4), filtered and evaporated to yield 7-tert-butyl-3,3-dimethyl-2,3-dihydrobenzo[b]furan. The aqueous layer is acidified to pH 2 with 1N HCl, and is extracted with Et2O (3×20 mL). The Et2O layers are combined, dried (MgSO4), filtered and evaporated to provide the desired carboxylic acid.

1. customa milky suspension results
2. temperatureis cooled to -50° C
3. temperatureto warm to 0° C
4. customthe mixture is partitioned between 0.1N NaOH (40 mL) and hexane (3×30 mL)
5. dry with materialThe hexane layer is dried (MgSO4)
6. filtrationfiltered
7. customevaporated