反应详情

Under a nitrogen atmosphere, to a tetrahydrofuran (50 mL) solution containing (R)-1-[(3R,5R)-5-(3,4,5-trifluorophenyl)morpholine-3-yl]ethanol (2.25 g), triphenylphosphine (4.51 g) and 4-nitrobenzoic acid (2.88 g) was dropwise added diisopropyl azodicarboxylate (3.39 mL) while cooling with ice. The resultant solution was stirred at the same temperature for 30 minutes, and then at room temperature for 2 hours. The reaction solution was diluted with water and ethyl acetate, and the organic layer was partitioned. The organic layer was washed with brine, and then dried over anhydrous magnesium sulfate. Solvent was removed by distillation under reduced pressure, and the resulting residue was crudely purified by silica gel column chromatography (heptane/ethyl acetate 8/2→1/1), to thereby obtain a crude product (3.6 g) of 4-nitrobenzoic acid (S)-1-[(3R,5R)-5-(3,4,5-trifluorophenyl)morpholine-3-yl]ethyl ester. A solution of the obtained crude product (3.53 g) in methanol (300 mL) was added sodium methoxide (4.39 mL, 28% methanol solution), and the resultant solution was stirred at room temperature for 1 hour. Solvent was removed by distillation under reduced pressure, and the resultant product was diluted with ethyl acetate and water. The organic layer was partitioned, washed with brine, and then dried over anhydrous magnesium sulfate. Solvent was removed by distillation under reduced pressure, and the resulting residue was purified by silica gel column chromatography (heptane/ethyl acetate 9/1→1/1), to thereby obtain the titled compound (1.19 g). The physical properties of the compound were as follows.

1. temperaturewhile cooling with ice
2. customthe organic layer was partitioned
3. washThe organic layer was washed with brine
4. dry with materialdried over anhydrous magnesium sulfate
5. customSolvent was removed by distillation under reduced pressure
6. customthe resulting residue was crudely purified by silica gel column chromatography (heptane/ethyl acetate 8/2→1/1)
7. customto thereby obtain a crude product (3.6 g) of 4-nitrobenzoic acid (S)-1-[(3R,5R)-5-(3,4,5-trifluorophenyl)morpholine-3-yl]ethyl ester
8. customSolvent was removed by distillation under reduced pressure
9. additionthe resultant product was diluted with ethyl acetate and water
10. customThe organic layer was partitioned
11. washwashed with brine
12. dry with materialdried over anhydrous magnesium sulfate
13. customSolvent was removed by distillation under reduced pressure
14. customthe resulting residue was purified by silica gel column chromatography (heptane/ethyl acetate 9/1→1/1)