Hydrogen Bromide → 1-(6-Bromo-7-oxo-4,5,6,7-tetrahydro-2-benzothiazolyl)-3-ethyl-urea

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Reaction Conditions

Reaction Steps

A solution of 1-(7-oxo-4,5,6,7-tetrahydro-2-benzothiazolyl)-3-ethyl-urea 4 (1.00 g, 4.18 mmol) and 48% HBr (aq) (0.24 mL, 2.09 mmol, 0.5 eq) in AcOH (18 mL) was treated dropwise with a solution of Br2 (0.23 mL, 4.39 mmol, 1.05 eq) in AcOH (1 mL) with stirring. The reaction mixture was heated at about 45° C. with stirring for about 16 hours with a condensor on top of the reaction flask. An orange colored suspension was obtained. The solid was filtered off and washed with AcOH (5 mL), toluene (2×3 mL) and Et2O (2×5 mL). After drying under vacuum, 1.11 g (83%) of the desired compound 7 was obtained. 1H NMR (DMSO) δ 11.15 (br s, 1H, NH), 6.73 (br s, 1H, NH), 4.87 (t, 1H, J=4.6 Hz, CH), 3.17 (m, 2H, CH2), 2.87 (dd, 2H, J=7.2, 4.4 Hz, CH2), 2.61–2.54 (m, 1H, CH2), 2.39–2.33 (m, 1H, CH2), 1.08 (t, 3H, J=7.2 Hz, CH3); LC/MS 318 (MH+); RP-HPLC RT 2.68 minutes.

Provenance & Evidence