[CH3:1][N:2]1[CH:6]=[CH:5][CH:4]=[CH:3]1.[Cl-].[Al+3].[Cl-].[Cl-].C([CH:13]([C:17](Cl)=[O:18])[C:14](Cl)=[O:15])C.[OH2:20].Cl[CH2:22][CH2:23]Cl>ClC(Cl)C>[CH2:22]([O:20][C:17](=[O:18])[CH2:13][C:14](=[O:15])[C:3]1[N:2]([CH3:1])[CH:6]=[CH:5][CH:4]=1)[CH3:23]
The starting material is prepared as follows: To the solution of 17 g of 1-methylpyrrole in 400 ml of 1,2-dichloroethane is added 28 g of anhydrous aluminum chloride in portions, while stirring and cooling to 10°-15°, followed by 27 g of ethyl malonyl chloride in 50 ml of dichloroethane at such a rate to keep the temperature between 10° and 15°. After stirring for 3.5 hours the temperature is allowed to rise slowly to 32° and the mixture is allowed to stand overnight at room temperature. It is treated with water, shaken, the organic layer separated, washed twice with water, dried and evaporated. The residual dark brown oil is distilled and the fraction boiling at 105-112/0.25 mm Hg collected, to yield the 1-methyl-β-oxo-2-pyrrolpropionic acid ethyl ester.
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