Methyl 3-amino-2-[(tert-butoxycarbonyl)amino]benzoate → 2,3-Diaminobenzoic acid methyl ester

Methyl 3-amino-2[(tert-butoxycarbonyl)amino]benzoate (61.8 g, 232 mmol) was added to trifluoroacetic acid (250 mL), and the mixture was stirred at room temperature for 3 hr. Trifluoroacetic acid was evaporated in vacuo, and the resulting solid was suspended in ethyl acetate (200 mL), collected by filtration and washed with ethyl acetate (50 mL). The solid was partitioned between ethyl acetate (300 mL) and saturated aqueous sodium hydrogen carbonate (400 mL), and the aqueous layer was seated and extracted with ethyl acetate (300 mL). The combined organic layer was washed with water (300 mL×2) and concentrated in vacuo to give the title compound (24.6 g, 148 mmol, 64%) as a brown solid. The filtrate described above was concentrated in vacuo, and the resulting solid was collected by filtration and washed with ethyl acetate. The filtrate was concentrated in vacuo, and the resulting solid was collected by filtration and washed with diethyl ether. The combined solid was partitioned between ethyl acetate (100 mL) and saturated aqueous sodium hydrogen carbonate (100 mL), and the aqueous layer was seated and extracted with ethyl acetate). The combined organic layer was washed with water and brine, dried over anhydrous sodium sulfate and concentrated in vacuo to give the title compound (8.29 g, 49.9 mmol, 22%) as a brown solid. Total amount: 32.9 g, 198 mmol, 85%.

1. customTrifluoroacetic acid was evaporated in vacuo
2. filtrationcollected by filtration
3. washwashed with ethyl acetate (50 mL)
4. customThe solid was partitioned between ethyl acetate (300 mL) and saturated aqueous sodium hydrogen carbonate (400 mL)
5. extractionextracted with ethyl acetate (300 mL)
6. washThe combined organic layer was washed with water (300 mL×2)
7. concentrationconcentrated in vacuo

ORD record

ord-ae38a5b148604aa18c69b9387e1cbb11

Source dataset

uspto-grants-2014_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08785460B2