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-fbec30172e044e11abbdbbc49be44803

Source dataset

uspto-grants-2012_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08148391B2