[CH3:1][C:2](=O)[CH2:3][CH2:4][CH3:5].[Cl:7][C:8]1[CH:13]=[CH:12][C:11]([C:14](=[O:18])[CH2:15][C:16]#[N:17])=[CH:10][CH:9]=1.NCCC(O)=O.C(O)(=O)C>CCOC(C)=O.C1(C)C=CC=CC=1>[Cl:7][C:8]1[CH:9]=[CH:10][C:11]([C:14]([C:15](=[C:2]([CH3:1])[CH2:3][CH2:4][CH3:5])[C:16]#[N:17])=[O:18])=[CH:12][CH:13]=1A mixture of pentan-2-one (20 mmol), 3-(4-chlorophenyl)-3-oxopropanenitrile (3.6 g, 20 mmol), β-alanine (180 mg, 2 mmol), acetic acid (2.6 mL) and toluene (60 mL) is heated to reflux in a Dean-Stark system for 18 h. The solution is cooled to RT, then diluted with EtOAc (50 mL), washed with 5% NaHCO3 (3×20 mL), water (20 mL), brine (20 mL), dried (Na2SO4) and finally concentrated in vacuo. A mixture of the two isomers is obtained as a colorless oil by chromatographic purification of the crude residue on silica gel using EtOAc:petroleum ether (0.5:9.5) as eluent.
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