Hydrochloric Acid → 3-(Ethoxycarbonyl)-5-methyl-1,2-oxazole-4-carboxylic acid

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Reaction Steps

The tert-butyl ester obtained in Step 2 (0.8 g, 3.13 mmol) was dissolved in formic acid (20 mL) and stirred at room temperature overnight. 6N aq. HCl (50 ml) was added. The mixture was extracted with DCM (3×50 mL). The combined organic layers were dried over sodium sulfate and concentrated to give the title compound, Intermediate 35: 3-(ethoxycarbonyl)-5-methylisoxazole-4-carboxylic acid, as a brownish oil (0.4 g, 64%). 1H NMR (300 MHz, MeOH-d4): δ 4.40 (q, 2H), 2.68 (s, 3H), 1.35 (t, 3H).

Provenance & Evidence