C[Si]([O:5][CH2:6][C:7]#[CH:8])(C)C.C([Mg]Br)C.[CH2:13]([N:20]1[CH2:25][CH2:24][CH2:23][C:22](=[O:26])[CH2:21]1)[C:14]1[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=1.[F-].C([N+](CCCC)(CCCC)CCCC)CCC>O1CCCC1>[CH2:13]([N:20]1[CH2:25][CH2:24][CH2:23][C:22]([C:8]#[C:7][CH2:6][OH:5])([OH:26])[CH2:21]1)[C:14]1[CH:15]=[CH:16][CH:17]=[CH:18][CH:19]=1
O-Trimethylsilylpropargyl alcohol (15.4 ml, 100 mmol) was added slowly at 0 to 5° C. to a cooled (0° C.) solution of ethylmagnesium bromide (1 M in tetrahydrofuran, 100 ml, 100 mmmol) in tetrahydrofuran. The reaction mixture was stirred at 0° C. for 15 minutes and then allowed to warm to room temperature over 30 minutes (exotherm and gas evolution observed), before recooling to 0° C. To this was added a solution of 1-benzyl-3-piperidone (15.16 g, 80.1 mmol) in tetrahydrofuran (30 ml), keeping the temperature below 5° C. The reaction mixture was stirred at room temperature overnight, quenched by addition of water/saturated aqueous ammonium chloride (50 ml/50 ml) and extracted with ethyl acatate (2×100 ml). The organic phases were washed with brine (100 ml), combined, dried (MgSO4) and evaporated to an amber oil (25.55 g). This oil was dissolved in tetrahydrofuran (50 ml), the solution cooled to 0° C. and treated with a solution of tetrabutylammonium fluoride (1.1 M in tetrahydrofuran, 100 ml, 110 mmol). After stirring at room temperature for 20 minutes the solution was concentrated in vacuo, diluted with water (250 ml) and extracted with ethyl acatate (2×100 ml). The extracts were washed with brine (100 ml), combined, dried (MgSO4) and evaporated to give the title product as an oil (18.65 g, 95%); m/z (ES+) 246 ([M+H]+).
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