Acetic Anhydride → 5-Chloro-7-hydroxy-3-(4-hydroxyphenyl)-4-oxo-4H-1-benzopyran
Reaction equation
[Cl:1][C:2]1[CH:7]=[C:6]([OH:8])[CH:5]=[C:4]([OH:9])[C:3]=1[C:10](=[O:19])[CH2:11][C:12]1[CH:17]=[CH:16][C:15]([OH:18])=[CH:14][CH:13]=1.[C:20](OC(=O)C)(=O)C.C([O-])(=O)C.[Na+]>>[Cl:1][C:2]1[C:3]2[C:10](=[O:19])[C:11]([C:12]3[CH:17]=[CH:16][C:15]([OH:18])=[CH:14][CH:13]=3)=[CH:20][O:9][C:4]=2[CH:5]=[C:6]([OH:8])[CH:7]=1Participants
4
Conditions
- Temperature
- 140 °C
Procedure
A solution consisting of 1-(2-chloro-4,6-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone (50 mg), acetic anhydride (1.2 mL) and sodium acetate (44 mg) was prepared. The solution was heated at 140° C. for 50 min, cooled to room temperature and stirred for 70 h. The soution was quenched with saturated sodium bicarbonate (10 mL), water (1 mL) and methanol (10 mL). After stirring for 3 h the solution was acidified to pH 5 with saturated potassium diphosphate and extracted with ethyl acetate (3×15 mL). The organics were dried over Na2SO4, filtered and concentrated in vacuo. The resulting yellow oil was diluted with toluene and dehydrated for 1.5 h using a Dean-Starke trap. Chromatography using reverse phase preperative HPLC provided the title compound (18 mg). 1H NMR (DMSO-d6): 11.07 (s br, 1H), 9.46 (s br, 1H), 7.03 (d, 1H, J=8.4 Hz), 6.88 (d, 1H, J=2.4 Hz), 6.79 (s, 1H), 6.78 (d, 2H, J=8.7 Hz), 2.18 (s, 3H); MS: 303 (MH+).