Methyl 2-(2-sulfamoylphenyl)acetate → 2H-1,2-Benzothiazin-3(4H)-one

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Reaction Steps

A solution of 18 g of 2-sulfamoylphenylacetic acid, methyl ester, in 125 g of 10% aqueous sodium hydroxide was stirred at room temperature for 4 hours. The mixture was filtered and the filtrate acidified by the addition of concentrated hydrochloric acid with ice-water cooling. The resulting precipitate was collected by filtration, washed with water, and dried to afford 12.5 g of 2H-1,2-benzothiazin-3(4H)-one, 1,1-dioxide as an off-white powder, m.p. 190°-195° C. NMR (CDCl3 /DMSO-d6): δ 11.3 (1H, br s, NH), 7.85 (1H, br d), 7.3-7.7 (3H, m) and 4.0 (2H, s).

Provenance & Evidence