[Cl:1][C:2]1[CH:3]=[C:4]([C:9](=[O:15])/[CH:10]=[CH:11]/[C:12]([OH:14])=[O:13])[CH:5]=[CH:6][C:7]=1[Cl:8].I[CH3:17]>CN(C=O)C.C1CCN2C(=NCCC2)CC1>[CH3:17][O:13][C:12](=[O:14])/[CH:11]=[CH:10]/[C:9]([C:4]1[CH:5]=[CH:6][C:7]([Cl:8])=[C:2]([Cl:1])[CH:3]=1)=[O:15]To an ice cooled solution of (E)-4-(3',4'-dichlorophenyl)-4-oxo-2-butenoic acid (2.4 g, 0.01 mol) in dry DMF (80 mL), DBU (1.5 mL, 0.01) was added dropwise on stirring, under nitrogen atmosphere. To the resulting stirred solution iodomethane (3.1 mL, 0.05 mol) dissolved in dry DMF (20 mL) was added dropwise over 20 min. The resulting solution was stirred at 0° C. for 1 hour and 3 hours at room temperature. The resulting reaction mixture was poured into ice-water on stirring, and the precipitate was filtered, washed with water and then with hexane. Recrystallization from diisopropyl ether/hexane provided the pure ester (2.2 g, 86%), pale yellow needles, mp. 108-109°.
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