4-Nitroaniline → N-(4-Nitrophenyl)glycine ethyl ester

A mixture of 4-nitroaniline (25.0 g, 181 mmol) and ethyl bromoacetate (10.0 ml, 90.5 mmol) was stirred at 80°-90° C. for 20 hours under a nitrogen atmosphere. Ethyl acetate (30 ml) was added to the reaction mixture and the mixture was refluxed under heating for 10 minutes, after which solid was collected by filtration and recrystallized from ethanol to give 13.1 g of ethyl (4-nitroanilino)acetate as a yellow solid (64%). A mixture of this solid (1.00 g, 4.46 mmol) and n-valeryl chloride (1.12 g, 9.36 mmol) was stirred at 80°-90° C. for 2 hours under a nitrogen atmosphere. The reaction mixture was purified by silica gel column chromatography (n-hexane/ethyl acetate=1/1) to give 948 mg of ethyl [4-nitro-N-(n-valeryl)anilino]acetate as a pale-yellow solid (69%). The solid (851 mg, 2.76 mmol) was dissolved in a mixture of chloroform (20 ml) and ethanol (30 ml) and 10% palladium carbon (80 mg) was added. The mixture was stirred at room temperature for 60 hours under a hydrogen atmosphere. After filtration, low boiling matters were distilled away from the filtrate under reduced pressure to give 759 mg of ethyl [4-amino-N-(n-valeryl)anilino]acetate as a colorless oil (99%).