Sulfuric Acid → 4-(5-Bromo-2-trifluoromethoxyphenyl)-2,2,6,6-tetramethylpyran-3,5-dione

Participants

Reaction Conditions

Reaction Steps

To an ice-cold solution of concentrated sulphuric acid (10 ml) is added a second solution of 2-(5-bromo-2-trifluoromethoxyphenyl)-4,4,6,6-tetramethyl-1,5-dioxaspiro[2.4]heptan-7-one (6.34 g, 15.00 mmol) in 1,2-dichloroethane (10 ml) dropwise over 5 minutes. This biphasic mixture is stirred vigorously for 2 hours at 0° C., then poured into ice-water, rinsing with a small amount of additional 1,2-dichloroethane/water. This mixture is then concentrated under vacuum to remove all organic solvents, until a free-flowing solid was produced. The solid is filtered, washed with water then isohexane, followed by drying under vacuum overnight. The solid is next redissolved in ethyl acetate, dried over magnesium sulfate, filtered and the filtrate concentrated in vacuo to afford 4-(5-bromo-2-trifluoromethoxyphenyl)-2,2,6,6-tetramethylpyran-3,5-dione (4.17 g, 68%).

Provenance & Evidence