HCID 86663660, compound → HCID 66823480, compound

Participants

Reaction Conditions

Reaction Steps

To ice-cold concentrated sulphuric acid (50 ml) is added a solution of crude 2-(5-bromo-2-ethylphenyl)-4,6,6-trimethyl-1,5-dioxaspiro[2.4]heptan-7-one (40 g) in 1,2-dichloroethane (50 ml) over 20 minutes. After further stirring at 0° C. for 1 hour the reaction mixture is carefully poured into ice (500 g), and the two phases separated. The aqueous phase is further extracted with dichloromethane (2×100 ml), then all organic fractions are combined, washed with water, and concentrated under reduced pressure. The crude product is re-dissolved in ethyl acetate (500 ml), extracted into 0.5M aqueous potassium carbonate, and washed with additional ethyl acetate (×2). The aqueous phase is then carefully acidified with concentrated hydrochloric acid, and the product extracted with ethyl acetate (3×150 ml). Organic fractions are combined, washed with brine then dried over magnesium sulfate, filtered, and the filtrate concentrated in vacuo. The crude product is further purified by flash column chromatography to afford 4-(5-bromo-2-ethylphenyl)-2,2,6-trimethylpyran-3,5-dione (14.10 g) as a white foam.

Provenance & Evidence