5-Bromosalicylaldehyde → 6-bromo-3-(5-bromo-2-thienyl)-4-hydroxy-2H-1-benzopyran-2-one

Participants

Reaction Conditions

Reaction Steps

A solution of titanium trichloride (7.71 g) in water (50 ml) was added to a solution of ethyl (5-bromo-2-thienyl)glyoxylate (5.0 g) and 5-bromo-2-hydroxybenzaldehyde (4.36 g) in dry acetic acid (50 ml) with stirring at 4° C. and the mixture was stirred for 11/2 hours. It was extracted with ethyl acetate and the extract was washed with water, brine, dried over magnesium sulfate and evaporated under reduced pressure. The residue was dissolved in toluene and p-toluenesulfonic acid (2.5 g) was added and the mixture heated under reflux for 21/2 hours. It was allowed to stand at room temperature overnight and evaporated under reduced pressure. The residue was purified by silica gel column chromatography to give 6-bromo-3-(5-bromo-2-thienyl)-4-hydroxy-2H-1-benzopyran-2-one, m.p. 234-6° C. (compound 27)

Provenance & Evidence