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

HRID 1470890Notes

Reaction equation

C(OC([CH:6]1[C:11](=[O:12])[C:10]([CH3:14])([CH3:13])[O:9][C:8]([CH2:16][O:17][CH3:18])([CH3:15])[C:7]1=[O:19])=O)C.S(=O)(=O)(O)O>O1CCOCC1.[Cl-].[Na+].O>[CH3:18][O:17][CH2:16][C:8]1([CH3:15])[C:7](=[O:19])[CH2:6][C:11](=[O:12])[C:10]([CH3:14])([CH3:13])[O:9]1

Participants

Conditions

Temperature: 110 °C

Procedure

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.

Workup

temperatureThe mixture is cooled to room temperature
extractionextracted with dichloromethane
extractionThe crude material is extracted into aqueous sodium hydroxide
washthe aqueous phase washed with dichloromethane
extractionextracted into dichloromethane (2×15 ml)
concentrationThe organic phase is concentrated in vacuo
customto give a crude oil which
customis purified by flash column chromatography on silica gel (isohexane/diethyl ether 7.5:1.5 ratio)

Sources & evidence

ORD record: ord-f6555ff9bcf24d8ea02ebfb0fae73559
Source dataset: uspto-grants-2015_04
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US09006429B2

Reaction notes

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