Malonic Acid → HCID 178524633, compound

Participants

Reaction Steps

A stirred suspension of 5-fluoroisatin, also known as 5-fluoro-2,3-indoledione, available from Sigma-Aldrich (10.00 g, 61 mmol) and malonic acid (18.91 g, 182 mmol) in acetic acid (400 ml) was refluxed for 16 h. Acetic acid was removed under reduced pressure, the residue was suspended in water (400 ml), filtered and washed with water (300 ml) to give a brown solid. The solid was stirred in NaHCO3 saturated aqueous solution (800 ml) and the insoluble material was filtered off. The filtrate was acidified to pH 1-2 with concentrated HCl and the resulting precipitate was filtered, washed with water (300 ml) and dried. The resulting pale yellow solid (10 g, Yield 54%) was used directly for synthesis of preparation 4 without further purification. The mixture was analysed by 1H NMR and LCMS: 1H NMR (500 MHz; d6-DMSO) δ 2.08 (s, 1.5 H), 7.01 (s, 1H), 7.35-7.37 (m, 0.5 H)*, 7.48-7.49 (m, 2H), 7.64-7.68 (m, 0.9H)*, 8.01-8.04 (m, 1H), 12.29 (brs, 1H), 13.38 (brs, 0.7H)* ppm.

Provenance & Evidence