2,2-Dimethyl-1,3-dioxane-4,6-dione → 2,2-Dimethyl-5-[2-(2,4,5-trifluoro-phenyl)-acetyl]-[1,3]dioxane-4,6-dione

Participants

Reaction Conditions

Reaction Steps

114 g (0.60 mol) of 2,4,5-trifluorophenylacetic acid was dissolved in 600 mL of THF. To this mixture, 107 g (0.66 mol) of carbonyldiimidazole was added with stirring (when a part of carbonyldiimidazole was added, a lot of solid was formed; subsequently, the solid thereby dissolved in the solution with further addition). Upon completion of the addition, the reaction mixture was warmed to 50° C. 95.1 g (0.66 mol) of Meldrum's acid was added, and the mixture was aged for 3 hours at 50° C. The mixture was concentrated to remove THF and the residue was dissolved in water (600 mL) and dichloromethane (800 mL), and then the pH value was adjusted to 2. The aqueous phase was separated and the organic phase was washed with 0.1N HCl and water (600 mL) respectively. The organic phase was dried and concentrated to obtain 182 g of a condensate, 5-[2-(2,4,5-trifluorophenyl)-acetyl]-2,2-dimethyl-1,3-dioxane-4,6-dione, as a solid (the re-crystallization can be carried out in ethyl acetate to obtain a white solid). Melting point: 101.5-103.5° C., Yield: 96%.

Provenance & Evidence