Triethylamine → 3-(4-Chloro-pyridin-3-yl)-5-methyl-isoxazole-4-carboxylic acid ethyl ester

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Reaction Steps

Combine chloro(4-chloro(3-pyridyl))(hydroxyimino)methane (2.40 g, 0.013 mol) with ethyl-2-butynoate (3.66 mL, 0.031 mol) in diethyl ether (150 mL) under a nitrogen atmosphere. Add triethylamine (2.27 mL, 0.016 mol) in a dropwise manner and stir over a weekend at ambient temperature. Quench the mixture with water and extract with ethyl acetate. Concentrate the combined extracts and elute over silica gel with methanol/dichloromethane to give the desired isoxazole (0.95 g, 27%) as an oil. ES(EI): M+ 266.0, 267.0, 268.0 m/z.

Provenance & Evidence