I[CH3:2].CSC.[CH3:6][C:7]([CH3:24])([CH3:23])[C:8](=[O:22])[CH:9]=[CH:10][C:11]1[CH:16]=[CH:15][C:14]([CH:17]2[O:21][CH2:20][CH2:19][O:18]2)=[CH:13][CH:12]=1.O>CS(C)=O.O1CCCC1>[O:21]1[CH2:20][CH2:19][O:18][CH:17]1[C:14]1[CH:15]=[CH:16][C:11]([CH:10]=[CH:9][C:8]2([C:7]([CH3:24])([CH3:23])[CH3:6])[CH2:2][O:22]2)=[CH:12][CH:13]=18.1 g (0.13 mol) of iodomethane are slowly added dropwise to a solution of 9.9 ml (0.135 mol) of dimethyl sulphide in 75 ml of absolute dimethylsulphoxide and 35 ml of absolute tetrahydrofuran, during which the internal temperature must not rise above 35° C. This suspension is subsequently stirred at room temperature overnight, and 15.7 g (0.14 mol) of potassium tert.-butylate are then added in portions. The mixture is subsequently stirred at room temperature for 30 minutes and cooled to 0° C., and 26 g (0.1 mol) of 4,4-dimethyl-1-[4-(1,3-dioxolan-2-yl)phenyl]-1-penten-3-one are added in portions. The reaction mixture is subsequently stirred at room temperature overnight, water is then added and the mixture is extracted three times with toluene. The combined toluene phases are washed with water and saturated sodium chloride solution, dried over sodium sulphate and concentrated. 25.6 g of crude 2-{2-[4-(1,3-dioxolan-2-yl)-phenyl]-ethenyl} -2-tert.-butyl-oxirane are obtained as an oil, which is further reacted directly. ##STR26##
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