Dichloromethane → Methyl 3-(2,4-dihydroxy-3-phenylphenyl)propanoate
Reaktionsgleichung
B(Br)(Br)Br.C[O:6][C:7]1[C:12]([C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=2)=[C:11]([O:19]C)[CH:10]=[CH:9][C:8]=1[CH2:21][CH2:22][C:23]([OH:25])=[O:24].[CH2:26](Cl)Cl>>[OH:6][C:7]1[C:12]([C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=2)=[C:11]([OH:19])[CH:10]=[CH:9][C:8]=1[CH2:21][CH2:22][C:23]([O:25][CH3:26])=[O:24]Komponenten
4
Versuchsvorschrift
BBr3 (4.72 g, 1.78 ml, 18.9 mmol) was carefully added through a syringe over 5 min to a stirred solution of dimethoxy acid 4c (1.35 g, 4.7 mmol) in anhydrous CH2Cl2 (20 ml). Resulted mixture was magnetically stirred for 8 h and concentrated under vacuum. The residue was co-evaporated with toluene (2×20 ml), dissolved in methanol (20 ml) and HCl gas was bubbled into the solution for 2 min. The material obtained after evaporation of the solvent was partitioned between cold water (30 ml) and ethyl acetate (100 ml). The organic phase was washed with saturated NaHCO3 (2×10 ml), brine (20 ml), dried over MgSO4 and concentrated. The resultant crude product was chromatographed on a short silica gel column eluting with ethyl acetate. Pure product fractions were concentrated to afford 1.2 g (94%) of 5c as a tan oil. 1H NMR (DMSO-d6): δ 8.95 (s, 1H), 7.82 (s, 1H), 7.24–7.36 (m, 5H), 6.83 (d, J=8.2 Hz, 1H), 6.38 (d, J=8.2 Hz, 1H), 3.59 (s, 3H), 2.75 (t, J=8.0 Hz, 2H), 2.52 (t, J=8.0 Hz, 2H).