[Cl:1][C:2]1[CH:3]=[C:4]([C@H:9]2[C:18]3[C:13](=[CH:14][CH:15]=[CH:16][CH:17]=3)[C:12](=[O:19])[CH2:11][CH2:10]2)[CH:5]=[CH:6][C:7]=1[Cl:8].[Li+].C[Si]([N-][Si](C)(C)C)(C)C.[CH:30](=O)[CH3:31]>C1COCC1>[Cl:1][C:2]1[CH:3]=[C:4]([C@H:9]2[C:18]3[C:13](=[CH:14][CH:15]=[CH:16][CH:17]=3)[C:12](=[O:19])/[C:11](=[CH:30]/[CH3:31])/[CH2:10]2)[CH:5]=[CH:6][C:7]=1[Cl:8]To a solution of (S)-4-(3,4-dichlorophenyl)-3,4-dihydronaphthalen-1 (2H)-one 1 (3.0 g, 10.3 mmol) in THF (50 mL) at −78 ° C was added LiHMDS (1.0 M, 12.4 mL, 12.4 mmol). The reaction mixture was stirred for 20 min before acetaldehyde (0.55 g, 0.70 mL, 12.41 mmol) was added. The reaction mixture was stirred and warmed to 0° C. over 2 h before being quenched with a saturated solution of NH4Cl (10 mL). The product was extracted with ethyl acetate, dried and concentrated. The residue was purified by silica gel column chromatography (ethyl acetate/hexane=1:7 to 1:5) to give (S,E)-4-(3,4-dichlorophenyl)-2-ethylidene-3,4-dihydronaphthalen-1(2H)-one 42 (2.9 g, 88%).
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