反应详情

In a 500 mL flame-dried round bottom flask fitted with a septum and under argon was placed 11.0 g (63.2 mmol) of the dioxolanate of (S)-malic acid (prepared by reaction of commercially available (S)-malic acid with excess dimethoxypropane and p-toluenesulfonic acid as a catalyst) dissolved in 200 mL anhydrous tetrahydrofuran. The reaction was cooled (-20° C. to -30° C.) and 70 mL of 1M borane-tetrahydrofuran complex was added dropwise over 2 hours. Following addition the reaction vessel was placed in a refrigerator at 4° C. for 11 hours, warmed to room temperature, stirred at room temperature for 9 hours and chromatographed (silica gel) using acetone as eluant. Following evaporation under reduced pressure, the residue was chromatographed as before to generate 9.1 g (90%) of the alcohol as a colorless unstable liquid which was dried under reduced pressure and utilized as such in the next reaction: IR (neat, cm-1) 3480 (br), 2994, 2940, 2888, 1791, 1220; 1H NMR (CDCl3) δ 4.58 (dd, J=5.1, 7.0 Hz, 1H), 3.91-3.79 (m, 2H), 2.28-2.13 (m, 1H), 2.13-1.97 (m, 1H), 1.64 (s, 3H), 1.57 (s, 3H).

1. customIn a 500 mL flame-dried round bottom flask
2. customfitted with a septum and under argon
3. temperatureThe reaction was cooled (-20° C. to -30° C.) and 70 mL of 1M borane-tetrahydrofuran complex
4. additionwas added dropwise over 2 hours
5. additionaddition the reaction vessel
6. customchromatographed (silica gel)
7. customevaporation under reduced pressure
8. customthe residue was chromatographed as before
9. customwas dried under reduced pressure
10. customsuch in the next reaction