To this flask was added THF (108 mL, 0.1 M), and the reaction mixture was allowed to stir at room temperature for 10 minutes to allow for complete dissolution of KOt-Bu. The reaction vessel was transferred to a -78 °C saturated dry-ice acetone bath and stirred for 10 minutes before a solution of acetate 4-9 (4.1 g, 10.8 mmol, 1.0 equiv) in THF (11 mL, 1.0 M) was added over 5 minutes, resulting in a yellow solution. After stirring for 0.5 hour at -78 °C, sat. aq. NH4Cl (25 mL) was added to the reaction mixture and the reaction vessel was removed from the dry-ice acetone bath and allowed to warm to room temperature. Once at room temperature, the layers were separated and the aqueous layer was extracted with Et2O (2 x 50 mL). The combined organic extracts were washed with brine (25 mL), dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure by rotary evaporation to provide 4-10 as a crude yellow oil (3.9 g).