[CH3:1][S:2][C:3]1[CH:10]=[CH:9][C:6]([CH:7]=O)=[CH:5][CH:4]=1.[C:11]([O:19][CH2:20][CH3:21])(=[O:18])[CH2:12][C:13]([O:15][CH2:16][CH3:17])=[O:14].C1(C)C=CC=CC=1>N1CCCCC1.C(O)(=O)C.O>[CH3:1][S:2][C:3]1[CH:10]=[CH:9][C:6]([CH:7]=[C:12]([C:13]([O:15][CH2:16][CH3:17])=[O:14])[C:11]([O:19][CH2:20][CH3:21])=[O:18])=[CH:5][CH:4]=14-(Methylthio)Benzaldehyde (3.04 g, .02 mol), diethyl malonate (3.20 g. .02 mol), toluene (25 mL), piperidine (4 drops) and acetic acid (2 drops) are mixed and heated at reflux for 2 hours with the water formed being removed azeotropically. The solution is cooled and 25 mL of water added stirring. After separation of the layers, the toluene is evaporated from the organic layer to yield the product, diethyl 2-[[4-(methylthio)phenyl]methylene]propanedioate, in essentially quantitative yield. When dissolved in methylene chloride, the product has an absorption maximum (λmax) at 330 nm in the ultraviolet absorption spectrum. The identity of the product is confirmed by mass spectroscopy analysis.
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