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:11].N1[CH2:26][CH2:25][CH2:24][CH2:23]1.[Cl:27][C:28]1C(O)=C(C=[CH:34][CH:35]=1)C=O>CS(C)=O>[CH2:1]([O:3][C:4]([CH:5]1[C:6]([CH:7]=[O:8])=[CH:34][C:35]2[C:23](=[CH:24][CH:25]=[CH:26][C:28]=2[Cl:27])[O:11]1)=[O:9])[CH3:2]Participants
Conditions
- Temperature
- 25 °C
Procedure
(E)-4-Oxo-but-2-enoic acid ethyl ester (2.7 mL, 22.99 mmol), 2-nitro benzoic acid (0.648 g, 3.83 mmol), and pyrrolidine (0.31 mL, 3.83 mmol) were added simultaneously to a solution of commercially available 3-chloro-2-hydroxy-benzaldehyde (5.0 g, 19.16 mmol) in dimethysulfoxide (20 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, yielded 5-chloro-3-formyl-2H-chromene-2-carboxylic acid ethyl ester as a solid (2.10 g, 50.1%).
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-079136ae1b0649809da0c9fad29bdf48
- Source dataset
- uspto-grants-2012_05
- Patent number
- US08178689B2
Reaction notes
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