Sulfuric Acid → HCID 66823800, compound

Participants

Reaction Conditions

Reaction Steps

To an ice-cold solution of concentrated sulphuric acid (12 ml) is added a second solution of 2-(5-bromo-2-difluoromethoxyphenyl)-4,4,6,6-tetramethyl-1,5-dioxaspiro[2.4]heptan-7-one (7.22 g, 18.00 mmol) in 1,2-dichloroethane (12 ml) dropwise over 5 minutes. This biphasic mixture is stirred vigorously for 2 hours at 0° C., then allowed to stand at room temperature overnight. The reaction mixture is poured into ice-water, rinsing with a small amount of additional 1,2-dichloroethane/water, then concentrated under vacuum to remove all organic solvents. The crude product is next extracted into ethyl acetate (×3), than all organics are combined, washed with brine, and dried over magnesium sulfate. The suspension is filtered and the filtrate is concentrated in vacuo then purified by flash column chromatography (10% to 25% ethyl acetate in hexane as eluant) to give an oil which is triturated with hexanes to afford 4-(5-bromo-2-difluoromethoxyphenyl)-2,2,6,6-tetramethylpyran-3,5-dione (2.08 g) as a white solid.

Provenance & Evidence