F-BuLi

M f-BuLi in pentane (14.7 mL, 22 mmol) was added dropwise to a stirred solution of 8 (R = /-Bu 2.63 g, 10 mmol) in anhyd THF (40 mL) at — 80C under an argon atmosphere, and the mixture was stirred at — 80 C for 1 h. After the addition of sublimed sulfur powder (320 mg, 10 mmol), the mixture was allowed to warm to rt over a 2-h period with stirring, and then EtOH (10 mL) was added. The mixture was heated at 55 C with stirring for 2-4 h, poured into ice-water (lOOmL), and then the whole was extracted with Et20 (3 x lOOmL). The combined extract was washed with brine, dried (MgS04), and concentrated in vacuo, and the residue was chromatographed (silica gel, hexane) yield 0.54 g (25%). 

A commercial solution of f-BuLi in pentane may be substituted for t-BuLi in heptane. However, the lower volatility and higher flash-point of the heptane solvent makes t-BuLi in heptane much easier and safer to handle than this alternative. 

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