[Br:1][C:2]1[C:3](Cl)=[N:4][CH:5]=[C:6]([S:8]([N:11]2[CH2:16][CH2:15][N:14]([CH2:17][CH3:18])[CH2:13][CH2:12]2)(=[O:10])=[O:9])[CH:7]=1.[O-:20][CH2:21][CH3:22].[Na+]>C(O)C>[Br:1][C:2]1[C:3]([O:20][CH2:21][CH3:22])=[N:4][CH:5]=[C:6]([S:8]([N:11]2[CH2:16][CH2:15][N:14]([CH2:17][CH3:18])[CH2:13][CH2:12]2)(=[O:10])=[O:9])[CH:7]=1A mixture of the product from stage d) (6.60 g, 17.9 mmol) and sodium ethoxide (6.09 g, 89.55 mmol) in ethanol (100 ml) was heated under reflux for 18 hours, then cooled. The reaction mixture was concentrated under reduced pressure, the residue partitioned between water (100 ml) and ethyl acetate (100 ml), and the layers separated. The aqueous phase was extracted with ethyl acetate (2×100 ml), the combined organic solutions dried (MgSO4) and evaporated under reduced pressure to afford the title compound as a brown solid, 6.41 g; Found C, 41.27; H, 5.33; N, 11.11. C13H20BrN3O3S requires C, 41.35; H, 5.28; N, 10.99%; δ (CDCl3, 300 MHz) 1.06 (3H, t), 1.48 (3H, t), 2.42 (2H, q), 2.56 (4H, m), 3.09 (4H, m), 4.54 (2H, q), 8.10 (1H, s), 8.46 (1H, s); LRMS: m/z 378, 380 (M+1)+.
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