Acetic Acid → 2-Ethylamino-5-nitro-phenol

Temperature

0 °C

2-Methyl-6-nitro-benzoxazole (12.25 g, 68.76 mmol) was dissolved in Tetrahydrofuran (500 mL) and Acetic acid (4.00 mL, 70.4 mmol) and was cooled at 0° C. Sodium tetrahydroborate (5.20 g, 138 mmol) was added over 10 min and the reaction was stirred at 0° C. for 30 min, then warmed to room temperature and stirred an additional 2.5 h. The undissolved borohydride was removed by filtration, and the filtrate conc. in vacuo to ˜100 mL. The filtrate was poured into water (800 mL) and neutralized with sodium bicarbonate powder. The aq. was extracted 3×200 mL DCM; the org. extract was washed with 100 mL water and 200 mL 1:1 brine:satd. sodium bicarbonate sol., then dried over sodium sulfate before being filtered through a ½″ h×2″ diameter plug of silica gel, washing with 500 mL 1:1 DCM:EtOAc. The filtrate was conc. to give 2-Ethylamino-5-nitro-phenol as a yellow solid (11.5 g, 92%)

1. temperaturewarmed to room temperature
2. stirringstirred an additional 2.5 h
3. customThe undissolved borohydride was removed by filtration
4. additionThe filtrate was poured into water (800 mL)
5. extractionThe aq. was extracted 3×200 mL DCM
6. extractionextract
7. washwas washed with 100 mL water and 200 mL 1:1 brine
8. dry with materialsodium bicarbonate sol., then dried over sodium sulfate
9. filtrationbefore being filtered through a ½″ h×2″ diameter plug of silica gel
10. washwashing with 500 mL 1:1 DCM

ORD record

ord-c4921a3823994489977cdf2ecb362052

Source dataset

uspto-grants-2013_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08552186B2