反应详情

Methyl 4-amino-3-chlorobenzoate (5.65 g; synthesized in accordance with Synthesis, 1985, 669) was dissolved in tetrahydrofuran (112 ml) and admixed with a solution of sodium hydrogen carbonate (7.67 g) in water (84.8 ml) and benzyl chloroformate (39.1 ml) and the mixture was stirred under a nitrogen atmosphere at room temperature for 22.5 hours. The reaction mixture was extracted with ethyl acetate and the ethyl acetate layer was washed three times with water and then twice with saturated brine. The ethyl acetate layer was dried over magnesium sulfate and then the solvent was distilled off under reduced pressure, and then the residue was purified by column chromatography on silica gel (ethyl acetate/hexane=1:7). A desired fraction was concentrated under reduced pressure and the residue was crystallized from a mixture of ethyl acetate and diisopropyl ether to yield methyl 4-benzyloxycarbonylamino-3-chlorobenzoate (7.51 g) as white crystals.

1. extractionThe reaction mixture was extracted with ethyl acetate
2. washthe ethyl acetate layer was washed three times with water
3. dry with materialThe ethyl acetate layer was dried over magnesium sulfate
4. distillationthe solvent was distilled off under reduced pressure
5. customthe residue was purified by column chromatography on silica gel (ethyl acetate/hexane=1:7)
6. concentrationA desired fraction was concentrated under reduced pressure
7. customthe residue was crystallized from a mixture of ethyl acetate and diisopropyl ether