反应详情

The compound (4.08 g, 12.0 mmol) synthesized in Example 6 (6 g) was dissolved in methanol (40 mL) and sodium methoxide (696 μL, 3.61 mmol) was added thereto, followed by stirring of the mixture at room temperature for 2 hours. After Dowex 50W×8 was added thereto until the reaction mixture became neutral and it was filtered, the solvent was distilled off under reduced pressure. The residue was dissolved in ethyl acetate (40 mL) and saturated aqueous sodium hydrogencarbonate solution (20 mL) and benzyloxy chloroformate (2.4 mL, 16.8 mmol) were added thereto under ice-cooling, followed by stirring of the mixture at the same temperature for 1 hour and 30 minutes. The organic layer was washed with saturated brine (50 mL) and dried with anhydrous sodium sulfate, followed by distilling off of the solvent under reduced pressure. The residue was purified using silica gel flash column chromatography (hexane:ethyl acetate, 2:1-1:1, V/V) to obtain the desired title compound (789 mg, yield 18%) as a pale yellow solid and its diastereomer (1.62 g, yield 36%) as a pale yellow oil.

1. filtrationit was filtered
2. distillationthe solvent was distilled off under reduced pressure
3. dissolutionThe residue was dissolved in ethyl acetate (40 mL)
4. temperatureunder ice-cooling
5. stirringby stirring of the mixture at the same temperature for 1 hour and 30 minutes
6. washThe organic layer was washed with saturated brine (50 mL)
7. dry with materialdried with anhydrous sodium sulfate
8. distillationby distilling off of the solvent under reduced pressure
9. customThe residue was purified