[OH:1][C:2]1[C:10]([Cl:11])=[CH:9][CH:8]=[CH:7][C:3]=1[C:4]([OH:6])=[O:5].[C:12](OC(=O)C)(=[O:14])[CH3:13].OS(O)(=O)=O>>[C:12]([O:1][C:2]1[C:10]([Cl:11])=[CH:9][CH:8]=[CH:7][C:3]=1[C:4]([OH:6])=[O:5])(=[O:14])[CH3:13]To a mixture of 2-hydroxy-3-chloro-benzoic acid (5.0 g, 29.0 mmol) in acetic anhydride (9.0 mL, 95.6 mmol) was added conc. H2SO4 (0.44 mL) at rt. Resulting suspension was heated in a 100° C. oil bath for 40 min. After cooled to about 50° C., the reaction mixture was poured onto ice (100 g) with stirring. Liquid was decanted off and the gooey residue was dissolved in methylene chloride, washed with water and brine, and dried over MgSO4. It was then filtered, and concentrated to give the title compound (5.89 g). 1H NMR (200 MHz, CDCl3): δ (ppm)=7.99 (dd, J=7.8, 1.6 Hz, 1H), 7.66 (dd, J=7.8, 1.6 Hz, 1H), 7.28 (m, 1H), 2.39 (s, 3H).
Wird geladen…