Trifluoroacetic acid → Ethyl 3-amino-2,5-dioxopyrrolidine-3-carboxylate

Participants

Reaction Steps

To a solution of the compound of Example 4 (970 mg) in dichloromethane (8 ml) was added trifluoroacetic acid (4 ml) and the mixture was stirred at room temperature for 6 hours. The reaction mixture was concentrated and to the resulting residue was added toluene to remove azeotropically the residual trifluoroacetic acid and then the mixture was concentrated again. The residue was dissolved in ethanol (25 ml) and thereto was added an appropriate amount of Raney nickel. This mixture was stirred vigorously at 40° C. under hydrogen (atmospheric pressure) for 24 hours. To the reaction mixture was added water (20 ml) and the mixture was filtered through a Celite pad and then the Celite was washed with ethanol. The mixture of the filtrate combined with the washers was adjusted to pH 7-8 with sodium bicarbonate and then thereto was added pH 7.4 phosphate buffer solution. This mixture was extracted with ethyl acetate and the extract was dried over magnesium sulfate and filtered. The filtrate was concentrated to give an oil which was then purified by a flash column chromatography (chloroform:methanol=20:1→10:1) to give the desired product (292 mg, 65%) as crystal.

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