[Si:1]([O:8][CH2:9][CH2:10][NH:11][C:12](=[O:18])[O:13][C:14]([CH3:17])([CH3:16])[CH3:15])([C:4]([CH3:7])([CH3:6])[CH3:5])([CH3:3])[CH3:2].[CH2:19](Br)[C:20]#[CH:21].[H-].[Na+]>CN(C=O)C>[Si:1]([O:8][CH2:9][CH2:10][N:11]([CH2:21][C:20]#[CH:19])[C:12](=[O:18])[O:13][C:14]([CH3:17])([CH3:16])[CH3:15])([C:4]([CH3:7])([CH3:6])[CH3:5])([CH3:3])[CH3:2]A solution of 800 mg of 10b and 800 μl of propargyl bromide in 8 ml of DMF was treated with 300 mg of NaH (60% dispersion in oil) at 0° C. The mixture was stirred at 0° C. for 1 hr and then for 1 hr at RT (the reaction mixture turned gradually deep brown). Then the mixture was poured onto ice water and the product was extracted with ethyl acetate. The combined organic layers were washed with water, dried and concentrated. The crude material was chromatographed over silica gel, using a gradient of heptane/ethyl acetate as eluent, to provide 650 mg of 10c. Rf (heptane/ethyl acetate 8/2) 0.50.
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