Acetone → 6-bromo-2,2-dimethyl-3,4-dihydro-2H-1-benzopyran-4-one

Participants

Reaction Steps

A solution of 1-(5-bromo-2-hydroxyphenyl)-ethanone (21.4 g, 0.1 mol), acetone (365 mL) and pyrrolidine (8.4 mL) in toluene (220 mL) was refluxed for 4 h. To the reaction mixture was added acetone (36.5 mL). The mixture was refluxed for 15 h. Then 1 N HCl (220 mL) was added, and the resulting mixture was extracted with ethyl acetate (200 mL, 3×). The combined organic layers were washed with water (150 mL), brine (150 mL), dried over anhydrous Na2SO4, filtered, and evaporated to give 6-bromo-2,2-dimethyl-chroman-4-one (18.0 g, 71%). 1H-NMR (CDCl3): 1.45 (s, 6 H), 2.71 (s, 2 H), 6.82 (d, 1 H), 7.52 (dd, 1 H), 7.96 (d, 1 H).

Provenance & Evidence