[C:1]([C:3]1[CH:8]=[CH:7][C:6]([CH2:9][CH2:10][CH2:11][CH2:12][CH2:13][CH2:14][CH2:15][CH3:16])=[CH:5][CH:4]=1)#[CH:2].C1CCCCC1.[CH3:23][C:24]1([CH3:31])[O:29][CH2:28][C:27](=[O:30])[CH2:26][O:25]1>C1COCC1.CCOCC>[CH3:23][C:24]1([CH3:31])[O:29][CH2:28][C:27]([C:2]#[C:1][C:3]2[CH:8]=[CH:7][C:6]([CH2:9][CH2:10][CH2:11][CH2:12][CH2:13][CH2:14][CH2:15][CH3:16])=[CH:5][CH:4]=2)([OH:30])[CH2:26][O:25]1To a solution of the product of Step A (0.05 g; 0.233 mmol) in anhydrous THF (2 ml) 2 M n-butyllithium in cylohexane (0.13 ml; 0.26 mmol) was added drop wise at −15° C. under N2. After stirring for 15 min at −15° C., 2,2-dimethyl-1,3-dioxan-5-one (0.034 g; 0.26 mmol) was added and the resulting mixture was allowed to warm up to room temperature, diluted to 15 ml with Et2O and washed with H2O (2×10 ml), brine and dried over anhydrous MgSO4 and filtered. The filtrate was evaporated to dryness under reduced pressure and the residue was purified by FCC (SiO2, hexane/EtOAc 95; 5) to give the title compound (0.03 g; 63%) as colourless oil. 1H-NMR (CDCl3) 7.33 (d, 2H, J=8.09 Hz); 7.09 (d, 2H, J=8.09 Hz); 4.11 (d, 2H, J=11.76 Hz); 3.83 (d, 2H, J=11.76 Hz); 3.99 (s, 1H); 2.57 (t, 2H, J=7.88 Hz); 1.56 (t, 3H, J=6.94 Hz); 1.49 (s, 3H); 1.46 (s, 3H); 1.26 (m, 10H); 0.86 (t, 3H, J=6.96 Hz).
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