反应详情

A mixture of (4-nitro-2-phenylbenzoyl)methionine methyl ester (7.69 g, 30 mmol), prepared as in Example 192A and aqueous saturated lithium hydroxide (20 mL) in methanol (50 mL) was refluxed for 6 hours. The reaction mixture was carefully acidified with concentrated hydrochloric acid (10 mL), and extracted with ethyl acetate (4×). The combine extracts were washed with brine, dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo. The residue was dissolved in dichloromethane (50 mL) and THF (10 mL) and 2-trimethylsilylethanol (3.72 g, 31.5 mmol), 1,3-diisopropylcarbodiimide (5.17 mL, 33 mmol) and 4-dimethylaminopyridine (30 mg) were added sequentially. After 4 hours, aqueous hydrochloric acid (0.1 N, 0.5 mL) was added and the reaction mixture was stirred for another 2 hours. The reaction mixture was then filtered through silica gel (40 g), and the filtrate was concentrated in vacuo. The residue was purified by column chromatography (5% ethyl ether-hexane) to give the title compound (8.90 g, 87%).

1. temperaturewas refluxed for 6 hours
2. extractionextracted with ethyl acetate (4×)
3. washThe combine extracts were washed with brine
4. dry with materialdried over anhydrous magnesium sulfate
5. filtrationfiltered
6. concentrationconcentrated in vacuo
7. dissolutionThe residue was dissolved in dichloromethane (50 mL)
8. filtrationThe reaction mixture was then filtered through silica gel (40 g)
9. concentrationthe filtrate was concentrated in vacuo
10. customThe residue was purified by column chromatography (5% ethyl ether-hexane)