[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([N:8]2[C:13](=[O:14])[N:12]([CH3:15])[C:11]3[CH:16]=[C:17]([OH:20])[CH:18]=[CH:19][C:10]=3[S:9]2(=[O:22])=[O:21])=[CH:4][CH:3]=1.Br[CH:24]([CH3:30])[C:25]([O:27][CH2:28][CH3:29])=[O:26].C(=O)([O-])[O-].[K+].[K+].O>CN(C)C=O>[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([N:8]2[C:13](=[O:14])[N:12]([CH3:15])[C:11]3[CH:16]=[C:17]([O:20][CH:24]([C:25]([O:27][CH2:28][CH3:29])=[O:26])[CH3:30])[CH:18]=[CH:19][C:10]=3[S:9]2(=[O:21])=[O:22])=[CH:4][CH:3]=1A mixture of 2-(4-chlorophenyl)-6-hydroxy-4-methyl-2H-1,2,4-benzothiadiazine-3(4H)-one 1,1-dioxide (678 mg), ethyl 2-bromopropionate (362 mg), and potassium carbonate (207 mg) in dry N,N-dimethyl formamide (2 ml) was stirred overnight at ambient temperature. The mixture was poured into water and extracted twice with ethyl acetate. The organic layers were washed with water, dried, and evaporated under reduced pressure. The residue was crystallized from n-hexane to yield 2-(4-chlorophenyl)-6-[1-(ethoxycarbonyl)ethoxy]-4-methyl-2H-1,2,4-benzothiadiazine -3(4H)-one 1,1-dioxide (816 mg). (R,S mixture)
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