The aqueous layer was extracted with CH2Cl2 (2 x 80 mL). The organic layers were collected, dried over Na2SO4, and concentrated under reduced pressure. The resulting residue was purified using a gradient of 0 to 20% EtOAc/hexanes on silica gel to yield 3 (colorless oil, 15.7 g, 43.7 mmol, 94% yield).