Water → 2,3,4,5-Tetrahydrobenzo[F][1,4]thiazepine 1,1-dioxide

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Reaction Steps

To a solution of 1-(1,1-dioxido-2,3-dihydro-1,4-benzothiazepin-4(5H)-yl)ethanone (240 g, 1.0 mol) in ethanol (1.0 L) was added sodium hydroxide (200 g, 5.0 mol) and water (700 mL). The mixture was refluxed overnight and then concentrated in vacuo. The residue was extracted by ethyl acetate (1500 mL×4). The combined organic layers were extracted by hydrochloric acid (2000 mL, 3 N). The acidic aqueous layer was washed with ethyl acetate (1500 mL×2), then basified with a saturated aqueous solution of sodium bicarbonate to pH>7, and extracted with ethyl acetate (1500 mL×4). The combined organic layers were dried over sodium sulfate, filtered and concentrated in vacuo to afford 151 g of 2,3,4,5-tetrahydro-1,4-benzothiazepine 1,1-dioxide (yield was 76%), MS obsd. (ESI+) [(M+H)+] 198, 1H NMR (400 MHz, DMSO-d6) δ ppm 7.89 (dd, J=1.2, 7.6 Hz, 1H), 7.56 (t, J=7.6 Hz, 1H), 7.47 (t, J=7.6 Hz, 1H), 7.42 (d, J=7.6 Hz, 1H), 4.04 (s, 2H), 3.32-3.30 (m, 2H), 3.30-3.25 (m, 2H), 2.64 (s, 1H).

Provenance & Evidence