Triethylamine → 4-Trifluoromethyl-3-methylthio-2-hydroxybenzoic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

100 g of ethyl 4-(methylsulphanyl)-3-oxobutanoate and 27.8 g of triethylamine were initially charged in 260 ml of toluene and cooled to 0° C. under nitrogen. Then 102.8 g of 4-ethoxy-1,1,1-trifluorobut-3-en-2-one were added dropwise at 0-7° C. within 30 minutes and the mixture was stirred for a further 5 h. After 16 hours, the reaction was warmed up to 18° C. The reaction mixture was concentrated, admixed with 150 ml of acetonitrile and concentrated at 5 mbar. The crude product was admixed with 2 equivalents of 10% sodium hydroxide solution while stirring and cooling with ice-water and stirred for 1 h, and the solids were filtered off with suction, washed three times with 50 ml of 3.5% sodium hydroxide solution and dried by suction. The solids were then admixed with 150 ml of water and 150 ml of toluene, and adjusted to pH 1 with about 150 ml of 10% HCl, and further HCl was metered in with continued stirring until the pH remains below 3. Then the filtered phases were separated and the water phase was extracted once more with toluene. The combined toluene phases were dried and concentrated: Yield 122.3 g (78% of theory). 1H NMR (CDCl3, 400 MHz): δ=11.77 ppm (1H, s), 7.93 ppm (1H, d), 7.23 ppm (1H, d), 4.47 ppm (2H, q), 2.44 ppm (3H, s), 1.45 ppm (3H, t).

Provenance & Evidence