Ethyl 3-[2-(aminosulfonyl)anilino]-3-oxopropanoate → 2H-1,2,4-Benzothiadiazine-3-acetic acid ethyl ester 1,1-dioxide

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Reaction Steps

A mixture of 12 (2.50 g, 8.73 mmol) in phosphorous oxychloride (50 mL) was heated under reflux for 6 h, cooled to room temperature, and concentrated in vacuo. The residue was dissolved in ethyl acetate (200 mL) and extracted with saturated Na2CO3 (100 mL). The organic layer was washed with 1 N HCl (50 mL), dried over MgSO4, and concentrated in vacuo to give 4c (1.99 g, 85%) as a yellow solid. 1H NMR (400 MHz, D6-DMSO) δ 12.22 (s, 1H), 7.79 (d, J=12 Hz, 1 H), 7.67 (t, J=10 Hz, 1 H), 7.45 (t, J=8 Hz, 1 H), 7.30 (d, J=8 Hz, 1 H), 4.15 (dt, J=7.2, 7.2 Hz, 2H), 3.69 (s, 2 H), 1.21 (t, J=7.2 Hz, 3 H).

Provenance & Evidence