CC(C)([O-:4])C.[K+].[CH3:7][S:8]([C:11]1[CH:18]=[CH:17][C:14]([CH:15]=O)=[CH:13][CH:12]=1)(=[O:10])=[O:9].[O:19]1[CH2:23][CH2:22][CH2:21][CH2:20]1>C(OCC)(=O)C>[CH2:20]([O:19][C:23](=[O:4])/[CH:22]=[CH:15]/[C:14]1[CH:17]=[CH:18][C:11]([S:8]([CH3:7])(=[O:10])=[O:9])=[CH:12][CH:13]=1)[CH3:21]Potassium tert-butoxide (10.96 g, 98 mmol) in tetrahydrofuran (60 ml) was added portionwise to a solution of triethyl phosphonoacetate (21.91 g, 98 mmol) in tetrahydrofuran (150 ml). The reaction mixture was stirred for 40 min at room temp. A solution of 4-(methylsulfonyl)benzaldehyde (Acros no.: 42490-0025; 10.0 g, 54 mmol) in tetrahydrofuran (60 ml) was added dropwise. The reaction mixture was stirred for 1 h at room temp. It was diluted with ethyl acetate (500 ml) and washed with 1 N hydrochloric acid (300 ml): The aqueous phase was extracted with ethyl acetate (2×100 ml). The combined organic layers were dried over magnesium sulphate. The solvent was removed in vacuo. The crude product was purified by crystallization from ethyl acetate/heptane to give 4.3 g of (E)-3-(4-(methylsulfonyl)phenyl)acrylic acid ethyl ester.
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