[CH3:1][C:2]1[NH:3][C:4]([CH3:24])=[C:5]([C:21](O)=[O:22])[CH:6]([C:12]2[CH:17]=[CH:16][CH:15]=[C:14]([N+:18]([O-:20])=[O:19])[CH:13]=2)[C:7]=1[C:8]([O:10][CH3:11])=[O:9].S(Cl)(Cl)=O.[Br:29][CH2:30][CH2:31][CH2:32][OH:33]>C(Cl)Cl.CN(C=O)C>[CH3:1][C:2]1[NH:3][C:4]([CH3:24])=[C:5]([C:21]([O:33][CH2:32][CH2:31][CH2:30][Br:29])=[O:22])[CH:6]([C:12]2[CH:17]=[CH:16][CH:15]=[C:14]([N+:18]([O-:20])=[O:19])[CH:13]=2)[C:7]=1[C:8]([O:10][CH3:11])=[O:9]A solution of 2,6-dimethyl-3-carbomethoxy-4-(3-nitrophenyl)-5-carboxy-1,4-dihydropyridine (107 g, 0.32 mol) in CH2Cl2 (520 mL) and DMF (100 mL) was cooled to 0° C. and thionyl chloride (28 mL, 0.39 mol) slowly added. The mixture was stirred at room temperature for 1 hour, then cooled to 5° C. Distilled 3-bromopropanol (35 mL, 3.9 mol) was slowly added, and the solution stirred for 1 hour at room temperature. The solution was then washed with water and the organic layer dried over sodium sulfate and evaporated under reduced pressure. The product was recrystallized from ethyl acetate to yield 2,6-dimethyl-3-carbomethoxy-4-(3-nitrophenyl)-5-(3-bromopropoxycarbonyl)-1,4-dihydropyridine (12, mp=146° C.).
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