After the reaction mixture was stirred for 6 hours at room temperature, sat. aq. NH4Cl (10 mL) was added and the layers were separated. The aqueous layer was extracted with EtOAc (3 x 20 mL). The combined organic extracts were washed with brine (15 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure by rotary evaporation to give a yellow foam. Purification by flash column chromatography on silica gel (10% EtOAc/hexanes to 35% EtOAc/hexanes) afforded SI-5 (73.6 mg, 72%) as a colorless foam.