Lithium Hydroxide → [7-(Methanesulfonyl-methyl-amino)-1,1-dioxo-1,4-dihydro-1lambda6-benzo[1,4]thiazin-3-yl]-acetic acid

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Reaction Conditions

Reaction Steps

A 2.0 M aqueous solution of lithium hydroxide (7.0 mL, 14.0 mmol) was added to a solution of 7-(methanesulfonyl-methyl-amino)-3-methoxycarbonylmethyl-1,1-dioxo-1H-1λ6-benzo[1,4]thiazine-4-carboxylic acid tert-butyl ester (Example 7d, 1.29 g, 2.80 mmol) in methanol at 25° C. The reaction mixture was stirred at 25° C. for 5 h, and then was partitioned between 0.5 M aqueous hydrochloric acid solution (150 mL) and ethyl acetate (2×150 mL). The organic layers were dried over sodium sulfate, filtered and concentrated in vacuo. Trituration of the residue with a 5:1 mixture of diethyl ether and acetonitrile afforded the desired product, [7-(methanesulfonyl-methyl-amino)-1,1-dioxo-1,4-dihydro-1λ6-benzo[1,4]thiazin-3-yl]-acetic acid (0.286 g, 0.83 mmol, 30% yield) as an orange solid. 1H NMR (400 MHz, DMSO-d6) δ: 2.96 (3H, s), 3.26 (3H, s), 3.48 (2H, s), 6.03 (1H, s), 7.29 (1H, d, J=8.6 Hz), 7.58 (1H, dd, J1=2.3 Hz, J2=9.5 Hz), 7.79 (1H, d, J=2.3 Hz), 10.80 (1H, s), 12.79 (1H, s).

Provenance & Evidence