[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([NH:8][NH2:9])=[CH:4][CH:3]=1.CC(C)[O-].[Na+].C([O:17][C:18](=O)[C:19]([CH2:21][N:22]([CH3:24])[CH3:23])=[CH2:20])C.S(=O)(=O)(O)O>C(O)(C)C>[CH3:23][N:22]([CH2:21][CH:19]1[CH2:20][N:8]([C:5]2[CH:6]=[CH:7][C:2]([Cl:1])=[CH:3][CH:4]=2)[NH:9][C:18]1=[O:17])[CH3:24]p-Chlorphenylhydrazine (14.5g) was added to a solution of sodium isopropoxide (2.3g of sodium) in dry isopropanol (200 ml). The solution was boiled under reflux and ethyl-2-dimethylaminomethylacrylate (15.7g) was added in one portion. After boiling for 20 minutes, the solution was cooled to 0° C in a stoppered flask. Sulphuric acid (125 ml, 2N) was added and the mixture was extracted with ether (3 × 250 ml). The ether extract was discarded and the aqueous solution was adjusted to a pH of 8 with sodium hydroxide solution (approx 125 ml, 2N). Extraction of the aqueous mixture with chloroform gave a pale yellow extract, which, after evaporation of the chloroform, gave a buff solid. The solid was recrystallised from carbon tetrachloride as colourless needles of 4-dimethylaminomethyl-p-chlorphenylpyrazolidin-3-one (9g, 35%, melting point 107° C).
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