2-Nitrobenzoic acid → 5-chloro-3-formyl-2H-chromene-2-carboxylic acid ethyl ester
Reaction equation
[CH2:1]([O:3][C:4](=[O:9])/[CH:5]=[CH:6]/[CH:7]=[O:8])[CH3:2].[N+](C1C=CC=CC=1C(O)=O)([O-])=O.N1CCCC1.[Cl:27][C:28]1[CH:35]=[CH:34][CH:33]=[C:32]([OH:36])[C:29]=1[CH:30]=O>CS(C)=O>[CH2:1]([O:3][C:4]([CH:5]1[C:6]([CH:7]=[O:8])=[CH:30][C:29]2[C:32](=[CH:33][CH:34]=[CH:35][C:28]=2[Cl:27])[O:36]1)=[O:9])[CH3:2]Participants
Conditions
- Temperature
- 25 °C
Procedure
(E)-4-Oxo-but-2-enoic acid ethyl ester (4.60 mL, 38.32 mmol), 2-nitrobenzoic acid (1.08 g, 6.39 mmol), and pyrrolidine (0.53 mL, 6.39 mmol) were added simultaneously to a solution of commercially available 2-chloro-6-hydroxy-benzaldehyde (5.0 g, 31.93 mmol) in dimethysulfoxide (30 mL) at 25° C. and the solution was stirred for 78 hours at 25° C. The reaction was quenched by the addition of water. The reaction mixture was then partitioned between water and ethyl acetate. The combined organics were washed with a saturated brine solution, dried over anhydrous sodium sulfate, filtered, rinsed and concentrated in vacuo. The residue obtained was purified on a silica gel Flash column chromatography using ethyl acetate-hexanes (1:1.2) as eluents, yielding 5-chloro-3-formyl-2H-chromene-2-carboxylic acid ethyl ester as a solid (2.08 g, 49.5%).
Workup
- customThe reaction was quenched by the addition of water
- customThe reaction mixture was then partitioned between water and ethyl acetate
- washThe combined organics were washed with a saturated brine solution
- dry with materialdried over anhydrous sodium sulfate
- filtrationfiltered
- washrinsed
- concentrationconcentrated in vacuo
- customThe residue obtained
- customwas purified on a silica gel Flash column chromatography
Sources & evidence
- ORD record
- ord-e9bfc1c75a7449e4b1b2a03060fb2c6c
- Source dataset
- uspto-grants-2012_05
- Patent number
- US08178689B2
Reaction notes
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