Sulfuric Acid → 2-Methoxymethyl-2,6,6-trimethylpyran-3,5-dione

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Reaction Conditions

Reaction Steps

To a solution of 2-methoxymethyl-2,6,6-trimethyl-3,5-dioxotetrahydropyran-4-carboxylic acid ethyl ester (2.11 g, 7.72 mmol) in dioxane (2.5 ml) is added 20% aqueous sulfuric acid (2.5 ml) and the mixture is heated at 110° C. for 2.5 hours. The mixture is cooled to room temperature, diluted with saturated brine and extracted with dichloromethane. The crude material is extracted into aqueous sodium hydroxide, the aqueous phase washed with dichloromethane, then acidified with concentrated hydrochloric acid and extracted into dichloromethane (2×15 ml). The organic phase is concentrated in vacuo to give a crude oil which is purified by flash column chromatography on silica gel (isohexane/diethyl ether 7.5:1.5 ratio) to afford 2-methoxymethyl-2,6,6-trimethylpyran-3,5-dione (0.250 g) as a pink solid.

Provenance & Evidence