Triethylamine → 1-Benzyl-3-acetyl-2,4-dioxopyrrolidine

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Reaction Steps

N-Benzylglycine methyl ester hydrochloride (23.0 g) is dissolved in ethanol (180 ml) and thereto is added triethylamine (11.1 g) under ice-cooling and further added dropwise diketene (9.2 g). The mixture is stirred at room temperature for 1 hour and distilled to remove the solvent. The residue is dissolved in chloroform, washed with water, 10% hydrochloric acid, and water in this order, dried and then distilled to remove the solvent. The residue is dissolved in xylene (360 ml) and the solution is added dropwise to a solution of sodium methoxide [which is prepared from metal sodium (2.6 g) and methanol (180 ml)], and the mixture is stirred at 80° C. for 2.5 hours while distilling off methanol. After cooling, the reaction mixture is extracted with water. The extract is acidified with 10% hydrochloric acid and extracted with ethyl acetate. The ethyl acetate extract is washed with water, dried and distilled to remove the solvent. The residue is recrystallized from n-hexane-isopropyl ether-diethyl ether to give 1-benzyl-3-acetyl-2,4-dioxopyrrolidine (20.33 g, 87.7%). m.p. 74°-75° C.

Provenance & Evidence