反应详情

2.5 M Hexane solution of normal butyl lithium (1.07 mL, 2.67 mmol) was slowly added under nitrogen to the 4-methoxybenzothiophene (92a, 368 mg, 2.24 mmol) obtained in Preparation Example 1 dissolved in an anhydrous tetrahydrofuran solution at −78° C., and the reaction mixture was stirred for 30 minutes. To the reaction mixture was slowly added a triisopropylborate solution (i-PrO)3B) (0.55 mL, 2.69 mmol) at room temperature, stirred for one hour, and the reaction was terminated by adding a solution of 2N hydrochloride. The resulting product was extracted with ethyl acetate, evaporated after a treatment with sodium sulfate, and concentrated under reduced pressure, recrystallized and filtered using hexane and ethyl acetate to give the target product 4-methoxybenzothiophene-2-boronic acid (95a, 289 mg, 62%).

1. customobtained in Preparation Example 1
2. stirringstirred for one hour
3. customthe reaction was terminated
4. additionby adding a solution of 2N hydrochloride
5. extractionThe resulting product was extracted with ethyl acetate
6. customevaporated after a treatment with sodium sulfate
7. concentrationconcentrated under reduced pressure
8. customrecrystallized
9. filtrationfiltered