[C:1]([C:6]1[C:7](=[O:22])[CH2:8][CH:9]([C:13]2[C:18]([CH3:19])=[CH:17][C:16]([CH3:20])=[CH:15][C:14]=2[CH3:21])[CH2:10][C:11]=1[OH:12])(=[O:5])[CH2:2][CH2:3][CH3:4].[CH3:23][O:24]C(Cl)Cl>ClC(Cl)C.[Ti](Cl)(Cl)(Cl)Cl>[C:1]([C:6]1[C:11](=[O:12])[CH2:10][CH:9]([C:13]2[C:14]([CH3:21])=[CH:15][C:16]([CH3:20])=[C:17]([CH:23]=[O:24])[C:18]=2[CH3:19])[CH2:8][C:7]=1[OH:22])(=[O:5])[CH2:2][CH2:3][CH3:4]To a solution of 2-butyryl-3-hydroxy-5-mesitylcyclohex-2-en-1-one (1.20 g) in dichloroethane (20 ml) at 0° C. was added titanium tetrachloride (3.00 g) over a period of 3 minutes. While the solution was stirred and cooled dichloromethyl methyl ether (0.46 g) in dichloroethane (20 ml) was added dropwise over a 25 minute period. After the addition was complete, the mixture was stirred for 5 minutes at 0° C., for 30 minutes at room temperature and for 2 hours under reflux. The cooled reaction mixture was poured into a separatory funnel containing crushed ice and was shaken thoroughly. The organic layer was separated, and the aqeuous solution was extracted with methylene chloride. The combined organic solution was washed with water, dried over anhydrous sodium sulfate and evaporated to dryness to give a crude brown oil (0.70 g). Purification by column chromatography over silica gel (eluant dichloromethane) gave 2-butyryl-3-hydroxy-5-(3-formyl-2,4,6-trimethylphenyl)cyclohex-2-en-1-one (0.35 g) as a pale yellow oil. Proton nuclear magnetic resonance spectrum (CDCl3 ; δ in ppm): 1.0 (3H, t); 1.68 (2H, m); 2.43 (3H, s); 2.48 (3H, s); 2.61 (3H, s); 2.65-4.20 (7H, m); 6.94 (1H, s); 10.54 (1H, s); 18.33 (1H, s).
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