Lithium Hydroxide → (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 (prepared as described in US patent application US 2008/0031852, 600 mg, 1.666 mmol) in methanol (30 mL) was cooled to 0° C. in an ice-water bath and treated with 2.0 M aqueous lithium hydroxide solution (4.17 mL, 8.332 mmol). The reaction mixture was allowed to warm to 25° C. and stirred for 1 h. The methanol was removed in vacuo and the reaction mixture was poured into 0.5 M aqueous hydrochloric acid solution (20 mL) on ice, extracted with ethyl acetate (3×50 mL), dried over sodium sulfate, filtered, and concentrated in vacuo to afford 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 (409 mg, 1.232 mmol, 73.9%), as a yellow solid. LC-MS calcd for C11H12N2O6S2 332.4, found 333.0 [M+H+].

Provenance & Evidence