After stirring at 65 °C for 14 hours, the reaction vessel was removed from the oil bath and cooled to room temperature. The reaction mixture was diluted with water (150 mL) and the layers were separated. The aqueous layer was extracted with EtOAc (3 x 50 mL). The combined organic extracts were washed with brine (150 mL), dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure by rotary evaporation to provide a crude brown oil. Purification by flash column chromatography on silica gel (10% EtOAc/hexanes to 35% EtOAc/hexanes) afforded 14-4 (1.54 g, 54% over 2 steps) as a colorless foam.