General procedure for the synthesis of ethyl 2-aminoacetoacetate hydrochloride from ethyl 2-(oxime-based) acetoacetate: a mixture of ethyl 2-(hydroxyimino)-3-oxobutanoate (5.2 g, 32.68 mmol), ethanol (50 mL), concentrated hydrochloric acid (5 mL), and Pd/C (1 g, 10%) was stirred for 48 hours at room temperature in a hydrogen atmosphere. Upon completion of the reaction, the solid catalyst was removed by filtration. The filtrate was concentrated under reduced pressure to afford ethyl 2-aminoacetoacetate hydrochloride (5 g, 84% yield) as an off-white solid, which could be used in the next step of the reaction without further purification. an LCMS assay showed [M+H]+ of 146.
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