反应详情

N,N-dimethylformamide dimethyl acetal (150 ml) is added dropwise to a mixture of 4-hydroxy-6-methyl-2-pyrone (100 g) in dioxane (400 ml) at 0° C. over 20 minutes. The mixture is warmed to room temperature and stirred an additional 4 hours. The precipitated solid is filtered, washed with isopropanol and dried to give 85.0 g of the title compound. The filtrate is concentrated and isopropanol (300 ml) is added to the residue. This mixture is kept at 0° C. overnight to give an additional 18.8 g of the title compound. Physical characteristics are as follows:

1. filtrationThe precipitated solid is filtered
2. washwashed with isopropanol
3. customdried