626-35-7

107-19-7

123770-62-7

The general procedure for the synthesis of ethyl 5-hydroxymethylisoxazole-3-carboxylate from ethyl nitroacetate and 2-propyn-1-ol was as follows: intermediate 4- Preparation of ethyl 5-(hydroxymethyl)isoxazole-3-carboxylate. In an Ace pressure tube, 2-propyn-1-ol (1.0 mL, 16.76 mmol) and ethyl nitroacetate (3.79 mL, 33.52 mmol) were dissolved in ethanol (23.5 mL), followed by the addition of 1,4-diazabicyclo[2.2.2]octane (DABCO, 0.194 g, 1.68 mmol). The reaction tube was sealed and the reaction was heated at 80 °C for 72 hours. After completion of the reaction, it was cooled to room temperature and the reaction mixture was concentrated to dryness under reduced pressure. The resulting residue was purified by fast column chromatography on silica gel, the eluent being a mixture of dichloromethane and methanol (methanol v/v fraction 0% to 6%), resulting in ethyl 5-(hydroxymethyl)isoxazole-3-carboxylate 2.32 g in 81% yield as an oil.ESI/APCI (+): m/z 172 ([M+H]+).