反应详情

温度

45 °C

To a suspension of magnesium (0.083 g, 3.42 mmol) in tetrahydrofuran (1.000 mL) was added 0.5 mL of a solution of example 34a (1.099 g, 3.11 mmol) in tetrahydrofuran (1.5 mL). The reaction mixture was warmed (about 40-50° C.) until reaction commenced. The remaining solution of starting bromide was added dropwise. The reaction mixture was stirred at ambient temperature for 1 hour. The resulting Grignard solution was added dropwise to a solution of trimethyl borate (0.696 mL, 6.23 mmol) in tetrahydrofuran (1.5 mL) at 0° C. The reaction mixture was stirred at ambient temperature. After 1 hour at ambient temperature, the reaction mixture was quenched with ice water and then neutralized with 2 M HCl. The mixture was extracted with ethyl acetate (3×). The combined organics were washed with saturated aqueous sodium chloride, dried over anhydrous sodium sulfate, filtered, and concentrated. The crude material was purified by flash chromatography (silica gel, 10-33% ethyl acetate/hexanes) to provide the title compound (0.650 g, 65.7% yield).

1. customuntil reaction commenced
2. stirringThe reaction mixture was stirred at ambient temperature
3. waitAfter 1 hour at ambient temperature
4. customthe reaction mixture was quenched with ice water
5. extractionThe mixture was extracted with ethyl acetate (3×)
6. washThe combined organics were washed with saturated aqueous sodium chloride
7. dry with materialdried over anhydrous sodium sulfate
8. filtrationfiltered
9. concentrationconcentrated
10. customThe crude material was purified by flash chromatography (silica gel, 10-33% ethyl acetate/hexanes)