Carbon Dioxide → HCID 73447335、化合物

At 10° C., 200 g of methyl 2-acetyl-4-methylpent-4-enoate (Preparation: cf. Tetrahedron (1985) 4633) in 2000 ml of aqueous 10% strength potassium hydroxide solution were admixed with 85 g of sodium nitrite, and the mixture was stirred at 23° C. for 18 hours. With ice-cooling, 1000 ml of 10% strength sulfuric acid were subsequently added dropwise such that the internal temperature remained below 10° C. The mixture was then stirred at 10° C. until evolution of CO2 had ceased. For work-up, the mixture was extracted with methyl tert-butyl ether, the combined organic phases were extracted with 3 N aqueous sodium hydroxide solution and the alkaline phases were adjusted to pH 1 using 20% strength sulfuric acid. They were then extracted with methylene chloride, the extract was dried over sodium sulfate and the solvent was removed under reduced pressure. This gave 142 g of the title compound as a yellow oil which crystallized on standing.