Trifluoroacetic acid methylene chloride → (7-Methanesulfonylamino-1,1-dioxo-1,4-dihydro-1lambda6-benzo[1,4]thiazin-3-yl)-acetic acid ethyl ester

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Reaction Steps

A solution of [7-(methanesulfonyl-tert-butyloxycarbonyl-amino)-4-tert-butyloxycarbonyl-1,1-dioxo-1,4-dihydro-1λ6-benzo[1,4]thiazin-3-yl]-acetic acid ethyl ester (Example 8f, 0.30 g, 0.54 mmol) in 1:1 dichloromethane/trifluoroacetic acid was stirred at 25° C. for 2 h. The reaction mixture was concentrated in vacuo and the residue was dissolved in ethyl acetate. The solution was washed with saturated aqueous sodium bicarbonate solution and brine solution. The organic layer was dried over sodium sulfate, filtered, and concentrated in vacuo to afford the desired product, (7-methanesulfonylamino-1,1-dioxo-1,4-dihydro-1λ6-benzo[1,4]thiazin-3-yl)-acetic acid ethyl ester (0.17 g, 0.47 mmol, 86% yield) as a yellow solid. 1H NMR (400 MHz, CDCl3) δ 1.32 (t, 3H, J=6.9 Hz), 3.03 (s, 3H), 4.02 (s, 2H), 4.21 (q, 2H, J=7.0 Hz), 5.02 (s, 1H), 6.96 (s, 1H), 7.02 (d, 1H, J=8.4 Hz), 7.53 (dd, 1H, J1=8.7 Hz, J2=2.4 Hz), 7.65 (d, 1H, J=2.2 Hz), 10.73 (s, 1H). LC-MS (ESI) calcd for C13H16N2O6S2 [M+H+] 361.04. found 361.18 [M+H+].

Provenance & Evidence