C([Li])CCC.[CH:6]([Si:9]([C:16]#[CH:17])([CH:13]([CH3:15])[CH3:14])[CH:10]([CH3:12])[CH3:11])([CH3:8])[CH3:7].CON(C)[C:21](=[O:30])[CH2:22][CH2:23][C:24]1[CH:29]=[CH:28][CH:27]=[CH:26][CH:25]=1>C1COCC1>[C:24]1([CH2:23][CH2:22][C:21](=[O:30])[C:17]#[C:16][Si:9]([CH:10]([CH3:11])[CH3:12])([CH:6]([CH3:8])[CH3:7])[CH:13]([CH3:15])[CH3:14])[CH:29]=[CH:28][CH:27]=[CH:26][CH:25]=1Following a procedure of Trost (Trost, B. M. et al., J. Am. Chem. Soc. 128, 6745-6754 (2006)); n-Butyllithium (2.5 M in hexanes, 10.4 ml, 26 mmol, 1.7 eq.) was added dropwise to a solution of triisopropylsilyl acetylene (5.8 ml, 26 mmol, 1.7 eq.) in THF (53 ml) at −78° C. After addition, the mixture was allowed to warm slowly to 0° C. and stirred for 1 h. The mixture was cooled to −78° C. and a solution of 83 (3.0 g, 15.3 mmol, 1 eq.) in THF (20 ml) was added dropwise. The mixture was then allowed to slowly warm to −10° C. and stirred for 1 h before being quenched by the addition of saturated aq. NH4Cl (50 ml). The mixture was extracted with EtOAc (3×30 ml) and the combined organic phases were washed with brine (50 ml) before being dried (MgSO4), filtered and concentrated to give the crude product. This was purified by column chromatography on silica, eluting with petrol/Et2O (100:0 to 98:2), giving the title product 84 as a clear, colourless oil (4.61 g, 96%).
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