Carbon Dioxide → Methyl 4,4-dimethoxybutanoate

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Reaction Steps

To 0.5 moles of diethylmalonate in 0.5 liters of dry benzene is added 0.5 moles of sodium hydride cautiously and the mixture stirred until hydrogen evolution ceases. Then 0.5 moles of bromoacetaldehydedimethylacetal [(CH3O)2 --CH--CH2 --Br] in 100 ml. of benzene is added and the mixture stirred overnight followed by refluxing for 2 hours. The reaction mixture is cooled, washed with water and purified by vacuum distillation to give β,β-dimethoxyethylmalonic acid diethyl ester. A mixture of 5 g. of this ester in 100 ml. of ethanol containing 5 g. of sodium hydroxide is heated under reflux until evolution of carbon dioxide ceases. The reaction mixture is then saturated with carbon dioxide and evaporated to dryness under vacuum. The residue is suspended in 50 ml. of dry dimethylformamide to which is added a large excess of methyl iodide. The reaction mixture is stirred at room temperature for about 24 hours and then poured into water. The resulting mixture is extracted with ether and the ether extracts combined, washed with water and evaporated to give 4,4-dimethoxybutyric acid methyl ester which is purified by distillation. A mixture of 4 g. of this methyl ester, 50 ml. of dry tetrahydrofuran and 1.1 equivalents of lithium aluminum hydride is refluxed overnight. The reaction mixture is allowed to cool and then filtered with water. This mixture is extracted with ether and the ether extracts are combined, washed, dried and evaporated to dryness to afford 4,4-dimethoxybutanol [(CH3O)2 --CH--CH2 --CH2 --CH2 --OH].

Provenance & Evidence