Hydrochloric Acid → Methyl 2-(5-hydroxy-6-nitro-1,3-dioxoisoindolin-2-yl)acetate

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A mixture of methyl 2-(5,6-dichloro-1,3-dioxoisoindolin-2-yl)acetate (1.420 g, 4.927 mmol) and potassium nitrite (1.678 g, 19.72 mmol) in dry DMF (23 ml) was heated to reflux for 5 hours. The reaction was cooled to room temperature, poured into 0.5N HCl (100 ml) and extracted twice with diethyl ether (2×100 ml). The combined organic layers were washed with 0.5N HCl (120 ml), with brine (100 ml) and dried over sodium sulfate. The solvent was removed, and the crude was purified by chromatography on silica gel cartridge (petroleum ether:ethyl acetate from 90:10 to 100% ethyl acetate). Two different impure fractions of desired compound were isolated. The first fraction was purified by trituration with MeOH affording 0.250 g of title compound. The second fraction was purified by flash chromatography on silica gel cartridge (petroleum ether:ethyl acetate:TFA from 80:20:0.2 to ethyl acetate:TFA=100:0.2) to obtain 0.160 g of title compound. The two clean portions of desired compound were mixed affording methyl 2-(5-hydroxy-6-nitro-1,3-dioxoisoindolin-2-yl)acetate (0.410 g, 1.463 mmol, 30% yield). MS/ESI+ 281.1 [MH]+.

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