To a flame-dried 25-mL round-bottomed flask equipped with a magnetic stir bar, was added THF (2 mL, 0.5 M) and diisopropylamine (147 µL, 1.1 mmol, 1.1 equiv). The reaction mixture was cooled to 0 °C by transferring the reaction apparatus to an ice-water bath. The reaction mixture was allowed to stir for 5 minutes at 0 °C, before n-BuLi (0.44 mL, 1.05 mmol, 1.05 equiv, 2.5 M in hexanes) was added dropwise to reaction mixture over 3 minutes.