Hydrochloric Acid → (7-Methanesulfonylamino-1,1-dioxo-1,4-dihydro-1lambda6-benzo[1,4]thiazin-3-yl)-acetic acid

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Reaction Conditions

Reaction Steps

A solution of (7-methanesulfonylamino-1,1-dioxo-1,4-dihydro-1λ6-benzo[1,4]thiazin-3-yl)-acetic acid ethyl ester (Example 8g, 0.245 g, 0.680 mmol) in methanol (15 mL) was cooled to 0° C. in an ice-water bath and treated with 2.0 M aqueous lithium hydroxide solution (1.7 mL, 3.40 mmol). The reaction mixture was allowed to warm to 25° C. and stirred for 1 h. The reaction was poured into 0.5 M aqueous hydrochloric acid solution (50 mL) on ice, extracted with ethyl acetate (3×50 mL), dried over magnesium sulfate, filtered, and concentrated in vacuo to give an orange solid. The crude solid was triturated with diethyl ether to afford the desired product, (7-methanesulfonylamino-1,1-dioxo-1,4-dihydro-1λ6-benzo[1,4]thiazin-3-yl)-acetic acid (0.175 g, 0.526 mmol, 77% yield) as a light orange solid. LC-MS (ESI) calcd for C11H12N2O6S2 332.4. found 333.3 [M+H+].

Provenance & Evidence