[CH2:1]([Li])CCC.[I-].C[S+](C)C.[O:11]1[CH2:15][CH2:14][O:13][CH:12]1[C:16]1[CH:21]=[CH:20][CH:19]=[C:18]([CH:22]=[CH2:23])[N:17]=1>CCCCCC.O1CCCC1>[CH:22]1([C:18]2[CH:19]=[CH:20][CH:21]=[C:16]([CH:12]3[O:13][CH2:14][CH2:15][O:11]3)[N:17]=2)[CH2:1][CH2:23]15.60 ml of a 1.6 M solution of n-butyllithium in hexane are introduced dropwise into a suspension of 2.71 g of trimethylsulfonium iodide (13.3 mmol) in 25 ml of tetrahydrofuran cooled to -15° C. The solution is stirred at -15° C. for 20 minutes under nitrogen, and then a solution of 1.57 g of 2-[1,3]dioxolan-2-yl-6-vinylpyridine (8.90 mmol) in 5 ml of tetrahydrofuran is added dropwise. After stirring for 1 hour at -15° C., the suspension is stirred for 3 hours at room temperature. The tetrahydrofuran is evaporated off, the residue is taken up in water and the mixture is extracted with ethyl acetate. The organic phase is washed with a saturated aqueous solution of sodium chloride, dried over magnesium sulfate, filtered and concentrated under vacuum. The title product is isolated by chromatography on a silica column (eluent: hexane/ethyl acetate; 50:50). 1.24 g of a colorless oil are obtained.
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