反应详情

温度

75 °C

The product from step (ii) (10 g; 0.034 mol) in tetrahydrofuran (35 ml) was added dropwise to a suspension of magnesium turnings (0.88 g) in tetrahydrofuran (5 ml). The mixture was warmed to 75° C. when the Grignard reaction started. Further of the bromo compound was slowly added and the external heat source removed, a gentle reflux being maintained. After complete addition, the mixture was heated for 30 mins under reflux and then cooled to 15° C. A dry nitrogen atmosphere was introduced and trimethyl borate (3.77 g; 0.0363 mol) was slowly added and the mixture stirred at 15°-20° C. for 16 hrs. A 20% soln of hydrochloric acid (50 ml) was slowly added, the organic layer was separated, and the aqueous layer extracted with ether (2×50 ml). The combined organic layers were washed with brine and dried over sodium sulphate. Upon evaporation of the solvents a yellow solid was obtained. Yield 8.7 g; 100%.

1. customthe Grignard reaction
2. customthe external heat source removed
3. temperaturea gentle reflux
4. temperaturebeing maintained
5. additionAfter complete addition
6. temperaturethe mixture was heated for 30 mins
7. temperatureunder reflux
8. temperaturecooled to 15° C
9. additionA dry nitrogen atmosphere was introduced
10. customthe organic layer was separated
11. extractionthe aqueous layer extracted with ether (2×50 ml)
12. washThe combined organic layers were washed with brine
13. dry with materialdried over sodium sulphate
14. customUpon evaporation of the solvents a yellow solid
15. customwas obtained