Hydrochloric Acid → 7-Bromo-4H-1-benzopyran-4-one

Participants

Reaction Steps

Conc. HCl (100 mL) was added to a solution of (E)-1-(4-bromo-2-hydroxyphenyl)-3-(dimethylamino)prop-2-en-1-one (31.9 g, 118 mmol) in dichloromethane (900 mL) and the reaction mixture was heated at reflux 40 min with vigorous stirring. After being cooled to room temperature, the organic layer was separated and the aqueous layer was extracted with dichloromethane. The combined organic layers were washed with 3M potassium carbonate soln, water, and dried over Na2SO4. Filtration and concentration gave 7-bromo-4H-chromen-4-one as a pale yellow solid. LCMS 224.9 (M+H); 1H NMR (DMSO-d6) 8.29-8.31 (d, 1H), 7.92-7.99 (m, 2H), 7.64-7.66 (dd, 1H), 6.37-6.39 (d, 1H).

Provenance & Evidence