反应详情

温度

-45 °C

The keto ester of Step 13 (24.8 g, 62.5 mmol) was dissolved in THF (230 mL) and cooled to -45° C. A THF (15 mL) solution of tetrahydro-1-methyl-3,3-diphenyl-1H,3H-pyrrolo[1,2-c][1,3,2]oxazaborole-borane adduct (J. Org. Chem., 56, 751 (1991), 4.55 g, 15.6 mmol) was added dropwise and the resulting mixture was stirred 20 minutes at -45° C. To this solution, 1.0M borane-THF (62.5 mL, 62.5 mmol) was added dropwise over 30 minutes. The reaction mixture was stirred 1 hour at -45° C. followed by another 2 hours with slow warming to -20° C. After cooling the solution of -40° C., it was poured onto 25% aq. NH4OAC (425 mL) and 1.0M diethanolamine (40 mL) at 0° C. and stirred vigorously for 20 minutes. The title compound was extracted with EtOAc (3×), dried over MgSO4 and concentrated under reduced pressure. The crude oil was purified by flash chromatography (25% to 50% EtOAc in hexanes) to yield 22.6 g (91%) of the desired product as an oil.

1. stirringThe reaction mixture was stirred 1 hour at -45° C.
2. waitfollowed by another 2 hours
3. temperaturewith slow warming to -20° C
4. temperatureAfter cooling the solution of -40° C., it
5. stirringstirred vigorously for 20 minutes
6. extractionThe title compound was extracted with EtOAc (3×)
7. dry with materialdried over MgSO4
8. concentrationconcentrated under reduced pressure
9. customThe crude oil was purified by flash chromatography (25% to 50% EtOAc in hexanes)