[I-].[CH3:2][S+](C)(C)=O.[CH3:7][O:8][CH2:9][O:10][C:11]1[C:16]([CH3:17])=[CH:15][CH:14]=[C:13]([O:18][CH2:19][O:20][CH3:21])[C:12]=1[C:22](=[CH2:28])[C:23]([O:25][CH2:26][CH3:27])=[O:24]>CS(C)=O>[CH3:7][O:8][CH2:9][O:10][C:11]1[C:16]([CH3:17])=[CH:15][CH:14]=[C:13]([O:18][CH2:19][O:20][CH3:21])[C:12]=1[C:22]1([C:23]([O:25][CH2:26][CH3:27])=[O:24])[CH2:2][CH2:28]1To a solution of trimethylsulfoxonium iodide (4.4 g, 20 mmol) in dry dimethyl sulfoxide (30 mL) sodium hydride (60% dispersion in mineral oil) (0.720 g, 18 mmol) was added and the reaction mixture was stirred for 1 hour at room temperature. A solution of ethyl 2-[2,6-bis(methoxymethoxy)-3-methyl-phenyl]prop-2-enoate (Intermediate 9, 3.5 g, 11.29 mmol) in dry dimethyl sulfoxide (15 mL) was slowly added and the reaction mixture was stirred for 1 hour at room temperature. The reaction was quenched with an aqueous saturated solution of ammonium chloride (10 ml), diluted with water (40 ml) and extracted with ethyl acetate (2×100 ml). The organic layer was washed with water (2×50 ml), dried over sodium sulphate, filtered and evaporated. The residue was purified by flash chromatography (Biotage system) on silica gel using a 100 g SNAP column and cyclohexane to cyclohexane/ethyl acetate 8:2 as eluents affording the title compound (3.1 g) as a colourless oil.
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