[CH3:1]N(C=O)C.P(Cl)(Cl)(Cl)=O.[Cl:11][C:12]1[CH:17]=[CH:16][C:15]([NH:18][C:19]([CH3:26])=[CH:20][C:21]([O:23][CH2:24][CH3:25])=[O:22])=[CH:14][CH:13]=1>ClCCCl>[Cl:11][C:12]1[CH:13]=[C:14]2[C:15](=[CH:16][CH:17]=1)[N:18]=[C:19]([CH3:26])[C:20]([C:21]([O:23][CH2:24][CH3:25])=[O:22])=[CH:1]2To a solution of 6.2 g (83 mmol) DMF in 50 ml of 1,2 dichloroethane was carefully added 19.1 g (126 mmol) of phosphoryl chloride. After stirring for 10 min at ambient temperature a solution of 20 g (83 mol) of ethyl 3-(4-chlorophenylamino)but-2-enoate in 50 ml of 1,2 dichloroethane was added slowly, while the mixture turned dark in an exothermic reaction. Stirring at ambient temperature was continued for another hour followed by heating with reflux for 6 h. The mixture was poured on to crushed ice, washed twice with water, dried over sodium sulfate, and concentrated under reduced pressure. The title ester was obtained from the residue via flash chromatography on silica gel with dichloromethane/hexane 4:1.
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