Hydrochloric Acid → (1,1-Dioxo-1,4-dihydro-1lambda6-benzo[1,2,4]thiadiazin-3-yl)-acetic acid

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Reaction Conditions

Reaction Steps

Solid sodium hydroxide (3.48 g, 87 mmol) was dissolved in water to make a saturated solution. The crude N-(2-sulfamoyl-phenyl)-malonamic acid ethyl ester was added into the sodium hydroxide solution. The reaction mixture was heated at 110° C. for 2.5 h, and then was cooled down to 25° C. The reaction mixture was acidified by slowly adding a 12.0 M aqueous hydrochloric acid solution (9.67 g, 116 mmol) while cooling in an ice-water bath. The product precipitated and was collected by vacuum filtration. The solid was washed with cold water and dried under high vacuum to afford the crude product, (1,1-dioxo-1,4-dihydro-1λ6-benzo[1,2,4]thiadiazin-3-yl)-acetic acid (5 g, 20.8 mmol, 71.7% over two steps), as a white solid. 1H NMR (400 MHz, DMSO-d6) δ: 3.58 (2H, s), 7.31 (1H, d, J=8.0 Hz), 7.44 (1H, dd, J1=7.8 Hz, J2=7.8 Hz), 7.67 (1H, dd, J1=7.8 Hz, J2=7.8 Hz), 7.79 (1H, d, J=7.9 Hz), 12.18 (1H, bs), 13.03 (1H, bs). LC-MS (ESI) calcd for C9H8N2O4S 240.02, found 241.1 [M+H+].

Provenance & Evidence