Carbon Disulfide → 1-Benzyl-3-(1,3-dithiolan-2-ylidene)-2,4-dioxopiperidine

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Reaction Steps

1-Benzyl-2,4-dioxopiperidine (2.03 g) and carbon disulfide (760 mg) are dissolved in dimethylsulfoxide (20 ml), and thereto is added dropwise a solution of potassium hydroxide (1.1 g) in water (3 ml) at room temperature. The mixture is stirred for 30 minutes and thereto is added dropwise a solution of 1,2-dibromomethane (1.87 g) in dimethylsulfoxide (3 ml). The mixture is stirred at room temperature for 2 hours and further at 60° C. for 1 hour. The reaction mixture is poured onto water and extracted with benzene-ethyl acetate. The extract is washed with water, dried and distilled to remove the solvent. The residue is purified by silica gel column chromatography (solvent, benzene:ethyl acetate=8:2) and is recrystallized from ethanol to give 1-benzyl-3-(1,3-dithiolan-2-ylidene)-2,4-dioxopiperidine (1.08 g) as pale yellow needles. m.p. 148°-150° C.

Provenance & Evidence