反应详情

温度

-78 °C

4-Bromo-3-methylbenzoic acid (3.96 g, 18.4 mmol) was dissolved in tetrahydrofuran (100 mL) and the solution was cooled to −78° C. n-Butyllithium in hexanes (16.2 mL of 2.5 M, 41 mmol) was added dropwise over 20 minutes. The reaction mixture was allowed to stir for 30 minutes at −78° C. and then acetone (1.35 mL, 18.4 mmol) was added in a dropwise manner. The reaction mixture was allowed to stir for 30 minutes at −78° C., and then allowed to warm to room temperature. The reaction mixture was then diluted with 1M aqueous sodium hydroxide (100 mL). The organic layer was discarded and then the aqueous layer was acidified with 4M aqueous hydrochloric acid. The aqueous layer was then extracted 3 times with ethyl acetate. The combined extracts were dried over sodium sulfate and then concentrated in vacuo. The crude material was purified by silica gel column chromatography using a gradient of 0-10% methanol in dichloromethane to give 4-(1-hydroxy-1-methyl-ethyl)-3-methyl-benzoic acid (1.51 g, 42%). 1H NMR (400 MHz, DMSO) δ 12.74 (s, 1H), 7.68 (dd, J=3.9, 2.5 Hz, 2H), 7.55 (d, J=8.7 Hz, 1H), 5.06 (s, 1H), 2.56 (s, 3H), 1.51 (s, 6H).

1. additionwas added dropwise over 20 minutes
2. stirringto stir for 30 minutes at −78° C.
3. temperatureto warm to room temperature
4. extractionThe aqueous layer was then extracted 3 times with ethyl acetate
5. dry with materialThe combined extracts were dried over sodium sulfate
6. concentrationconcentrated in vacuo
7. customThe crude material was purified by silica gel column chromatography