Ethanol → 2-(3,4-dihydroxy-5-nitrophenyl)-4H-1-benzopyran-4-one
Reaction equation
B(Br)(Br)Br.C[O:6][C:7]1[CH:8]=[C:9]([C:18]2[O:19][C:20]3[CH:28]=[CH:27][CH:26]=[CH:25][C:21]=3[C:22](=[O:24])[CH:23]=2)[CH:10]=[C:11]([N+:15]([O-:17])=[O:16])[C:12]=1[O:13]C.C(O)C>C(Cl)Cl>[OH:6][C:7]1[CH:8]=[C:9]([C:18]2[O:19][C:20]3[CH:28]=[CH:27][CH:26]=[CH:25][C:21]=3[C:22](=[O:24])[CH:23]=2)[CH:10]=[C:11]([N+:15]([O-:17])=[O:16])[C:12]=1[OH:13]Participants
Procedure
A solution of 10 ml of boron tribromide in 50 ml of methylene chloride are added dropwise within 30 minutes at -10° to a solution of 1.0 g of 2-(3,4-dimethoxy-5-nitrophenyl)-4H-1-benzopyran-4-one in 100 ml of methylene chloride under an argon atmosphere, whereupon the mixture is stirred at room temperature overnight. After cooling to -20°, 20 ml of ethanol are added dropwise thereto. The mixture is then evaporated in a water-jet vacuum. The yellow residue obtained is extracted with water/ethyl acetate. The organic phase is washed with water, dried over sodium sulfate and evaporated. After recrystallization from ethanol/ethyl acetate, there is obtained 2-(3,4-dihydroxy-5-nitrophenyl)-4H-1-benzopyran-4-one in the form of yellow crystals of m.p. >240° (dec.).
Workup
- temperatureAfter cooling to -20°
- customThe mixture is then evaporated in a water-jet vacuum
- customThe yellow residue obtained
- extractionis extracted with water/ethyl acetate
- washThe organic phase is washed with water
- dry with materialdried over sodium sulfate
- customevaporated
- customAfter recrystallization from ethanol/ethyl acetate
Sources & evidence
- ORD record
- ord-794a036a316240e7a9f08641ade86edc
- Source dataset
- uspto-grants-1995_02
- Patent number
- US05389653
Reaction notes
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