Boron tribromide → 3-(4-Hydroxyphenyl)-7-(3-hydroxypropyl)chromen-2-one
Reaktionsgleichung
[OH:1][CH2:2][CH2:3][CH2:4][C:5]1[CH:14]=[C:13]2[C:8]([CH:9]=[C:10]([C:16]3[CH:21]=[CH:20][C:19]([O:22]C)=[CH:18][CH:17]=3)[C:11](=[O:15])[O:12]2)=[CH:7][CH:6]=1.B(Br)(Br)Br>ClCCl>[OH:22][C:19]1[CH:18]=[CH:17][C:16]([C:10]2[C:11](=[O:15])[O:12][C:13]3[C:8]([CH:9]=2)=[CH:7][CH:6]=[C:5]([CH2:4][CH2:3][CH2:2][OH:1])[CH:14]=3)=[CH:21][CH:20]=1Komponenten
4
Edukt 2
Produkt 1
Reagenzien, Katalysatoren, Lösungsmittel 1
Versuchsvorschrift
1.00 g (3.22 mmol) of 7-(3-hydroxypropyl)-3-(4-methoxyphenyl)chromen-2-one (see Ex. 3.1) is initially introduced in 30 ml of dichloromethane, and a solution of 0.4 ml (4.2 mmol) of boron tribromide in 10 ml of dichloromethane is added with ice-cooling. The cooling is removed, and the batch is stirred overnight at room temp. The solution is added to ice-water, acidified using 2 N hydrochloric acid and extracted three times with ethyl acetate. The combined org. phases are washed with water and dried over sodium sulfate. The solvent is removed in vacuo, and the residue is chromatographed on silica gel with toluene/ethyl acetate (1:1). After first runnings, 3-(4-hydroxyphenyl)-7-(3-hydroxypropyl)chromen-2-one is obtained as colourless solid in a second fraction (Rf=0.3).