[H-].[Na+].[CH3:3][CH:4]([C:10]([O:12][CH2:13][CH3:14])=[O:11])[C:5]([O:7][CH2:8][CH3:9])=[O:6].[Cl:15][C:16]1[CH:21]=[C:20](Cl)[CH:19]=[CH:18][C:17]=1[N+:23]([O-:25])=[O:24]>CN(C)P(N(C)C)(N(C)C)=O.O>[CH3:3][C:4]([C:20]1[CH:19]=[CH:18][C:17]([N+:23]([O-:25])=[O:24])=[C:16]([Cl:15])[CH:21]=1)([C:5]([O:7][CH2:8][CH3:9])=[O:6])[C:10]([O:12][CH2:13][CH3:14])=[O:11]The starting material can also be prepared as follows: 4.8 g 50% sodium hydride in mineral oil are added to 100 ml hexamethylphosphoramide while stirring under nitrogen. Hereupon 17.1 g diethyl α-methylmalonate are added and the mixture slowly heated to 100°. The solution of 19.2 g 2,4-dichloro-nitrobenzene in 20 ml hexamethylphosphoramide is added dropwise during 1/2 hour and the temperature kept at 100° for seven hours. After cooling, the mixture is diluted with water, concentrated in vacuo, the residue taken up in water and extracted with benzene. The extract is washed with water, dried, filtered, evaporated, the residue distilled and the fraction boiling at 147°-148°/0.25 mm Hg collected, to yield the diethyl α-methyl-α-(3-chloro-4-nitrophenyl)-malonate. (The analogously prepared diethyl α-ethyl-α-(3-chloro-4-nitrophenyl)-malonate boils at 170°-174°/1 mm Hg.)
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