Triethylamine → Ethyl 3-(2-fluorophenyl)-5-methylisoxazole-4-carboxylate

Participants

Reaction Steps

To a solution of ethyl 2-butynoate (65.5 mL, 562 mmol) and triethylamine (80.7 mL, 576 mmol) in ethanol (600 mL) was added, at 0-4° C. over 2 h, 500 mL of a solution of (E)- and/or (Z)-N-hydroxy-2-fluoro-benzenecarboximidoyl chloride (83.3 g 480 mmol) in ethanol (900 mL). Ethyl 2-butynoate (44.6 ml, 383 mmol) in ethanol (125 mL) was added at 0° C., then the remaining 400 ml of the (E)- and/or (Z)-N-hydroxy-2-fluoro-benzenecarboximidoyl chloride solution were added over a 1 h period. The resulting mixture was then stirred for 48 h at room temperature and evaporated. The mixture was then poured onto HCl (1.2 L), and extracted with tert-butyl methyl ether. The combined organic layers were then washed with water and brine, dried over sodium sulfate and evaporated. Purification by chromatography (SiO2, heptane:ethyl acetate=100:0 to 9:1) afforded the title product (73.6 g, 62%) which was obtained as a yellow oil, MS: m/e=250.1 [M+H]+.

Provenance & Evidence