Hydrochloric Acid → Ethyl 7-(1,1-dimethylethyl)-2-(trifluoromethyl)-2h-1-benzopyran-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

A one liter three-neck flask was charged with 4-tert-butylsalicylaldehyde (Step 1) (100.0 g, 0.56 mole), dimethylformamide (110 mL), and potassium carbonate (79.9 g, 0.58 mole) causing the temperature of the mixture to rise to 40° C. Ethyl 4,4,4-trifluorocrotonate (118.0 g, 0.70 mole) in dimethylformamide (110 mL) was added and the mixture heated to 60° C. at which time the reaction temperature rose to 70° C. The reaction was cooled to 60° C., maintained at 60° C. (with added heating) for 8.5 hours and cooled to room temperature. Ethyl acetate (600 mL) and 3 N HCl (600 mL) were added, mixed, and the layers separated. The aqueous phase was extracted with ethyl acetate and the organic phases were combined. The combined organic phases were washed with brine-water (1:1), brine, dried over MgSO4, filtered and concentrated in vacuo, yielding a semi-solid. Hexane (600 mL) was added with mixing and the mixture was filtered. The filtrate was washed with brine, dried over MgSO4, filtered and concentrated in vacua yielding a solid. This solid was dissolved in hot ethanol (600 mL). Water (190 mL) was added which induced crystallization. Filtration of the mixture and drying of the product provided the desired ester as a crystalline solid (131.3 g, 71%): mp 91.0–94.9° C. This material was of suitable purity to be used in subsequent steps without further purification.

Provenance & Evidence