反应详情

The product from Example G ((S)-2-(9H-fluoren-9-ylmethoxycarbonylamino)-3-(4-hydroxyphenyl)-propionic acid tert-butyl ester) (4.00 g, 8.64 mmol), 2-pyridylcarbinol (0.92 mL, 9.50 mmol) and triphenylphosphine (2.24 g, 8.64 mmol) were dissolved in 50 mL of dry THF. The solution was cooled in an ice bath under an argon atmosphere and diethyl azidocarboxylate (1.36 mL, 8.64 mmol) was added dropwise over 20 minutes. The ice bath was removed and the solution allowed to stir overnight at room temperature. The solution was concentrated under reduced pressure and partitioned between ethyl acetate and water (100 mL each) and separated. The organic layer was washed with 10% aqueous HCl (2×50 mL), 10% sodium bicarbonate (2×50 mL), brine (2×50 mL), dried with magnesium sulfate, filtered, and concentrated under reduced pressure to a foam (4.80 g). The foam was purified by chromatography (silica gel, 1:1.5 ethyl acetate/hexane) to give the product as a white foam (3.90 g, 82%).

1. temperatureThe solution was cooled in an ice bath under an argon atmosphere
2. customThe ice bath was removed
3. concentrationThe solution was concentrated under reduced pressure
4. custompartitioned between ethyl acetate and water (100 mL each)
5. customseparated
6. washThe organic layer was washed with 10% aqueous HCl (2×50 mL), 10% sodium bicarbonate (2×50 mL), brine (2×50 mL)
7. dry with materialdried with magnesium sulfate
8. filtrationfiltered
9. concentrationconcentrated under reduced pressure to a foam (4.80 g)
10. customThe foam was purified by chromatography (silica gel, 1:1.5 ethyl acetate/hexane)