After the reaction mixture had stirred at room temperature for 1 hour, the reaction mixture was diluted with 1:1 sat. aq. NaHCO3/brine (5 mL) and the layers were separated. The aqueous layer was extracted with Et2O (3 x 5 mL). The combined organic extracts were washed with brine (5 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure by rotary evaporation to give a crude yellow solid. Purification by flash column chromatography on silica gel (10% Et2O/hexanes to 20% Et2O/hexanes) afforded 6-15 as a colorless oil (48 mg, 76%).