(2S)-2-[(4-bromo-2-nitrophenyl)amino]butanoic acid → (3S)-7-bromo-3-ethyl-3,4-dihydroquinoxalin-2(1H)-one
Reaction equation
[Br:1][C:2]1[CH:7]=[CH:6][C:5]([NH:8][C@@H:9]([CH2:13][CH3:14])[C:10](O)=[O:11])=[C:4]([N+:15]([O-])=O)[CH:3]=1>CO.C(O)(=O)C.[Fe]>[Br:1][C:2]1[CH:3]=[C:4]2[C:5]([NH:8][C@@H:9]([CH2:13][CH3:14])[C:10](=[O:11])[NH:15]2)=[CH:6][CH:7]=1Participants
Procedure
A solution of (2S)-2-[(4-Bromo-2-nitrophenyl)amino]butanoic acid (8.3 g, 27.4 mmol) in methanol (20 mL) and acetic acid (20 mL) was treated with iron filings (5.0 g, 89.5 mmol). The reaction was heated at reflux for 3 h, after which time the reaction was cooled, and filtered. The filtrate was concentrated in vacuo, and the resulting residue was diluted with ethyl acetate, washed with a saturated aqueous solution of sodium bicarbonate, dried over magnesium sulfate, and concentrated in vacuo to yield 3.8 g (54%) of (3S)-7-bromo-3-ethyl-3,4-dihydroquinoxalin-2(1H)-one as a yellow solid. [α]D25=+33.23° (c=0.008 G/ML, DMSO); MS (ESI) m/z 255/257 ([M+H]+); Anal. Calcd for C10H11BrN2O: C, 47.08; H, 4.35; N, 10.98. Found: C, 46.98; H, 4.08; N, 10.90.
Workup
- temperatureThe reaction was heated
- temperatureat reflux for 3 h
- temperatureafter which time the reaction was cooled
- filtrationfiltered
- concentrationThe filtrate was concentrated in vacuo
- additionthe resulting residue was diluted with ethyl acetate
- washwashed with a saturated aqueous solution of sodium bicarbonate
- dry with materialdried over magnesium sulfate
- concentrationconcentrated in vacuo
Sources & evidence
- ORD record
- ord-3450f8f4bae841b0baf2451c3d2e8419
- Source dataset
- uspto-grants-2008_04
- Patent number
- US07351709B2
Reaction notes
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