Phosphorus oxychloride → Ethyl (7-methoxy-1,1-dioxido-4H-1,2,4-benzothiadiazin-3-yl)acetate

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Reaction Steps

A mixture of 10 (8.0 g, 28 mmol) in phosphorous oxychloride (150 mL, 1.64 mol) was heated to reflux for 2.5 hours, then cooled to room temperature and concentrated in vacuo. The residue was then dissolved in ethyl acetate and neutralized with saturated aqueous sodium bicarbonate. The organic phase was washed with 2 N hydrochloric acid and then brine, dried over magnesium sulfate, filtered, and concentrated in vacuo. The solid product was then triturated in diethyl ether to produce 6.6 g of the desired product (4a) as a brown solid in 79% yield. See procedure described in International Patent Application No. PCT/US03/16374. 1H NMR (400 MHz, DMSO-d6): δ12.20 (s, 1H), 7.27 (m, 2 H), 7.20 (s, 1H), 4.14 (q, 2H, J=7.2 Hz), 3.73 (s, 3H), 3.66 (s, 2H), 1.21 (t, 3H, J=7.6 Hz); LC-MS (ESI+): m/e=299.1 [M+1]+.

Provenance & Evidence