After stirring at 45 °C for 18 hours, the reaction vessel was removed from the oil bath and cooled to room temperature. Once at room temperature, the reaction mixture was diluted with water (20 mL) and EtOAc (10 mL). The layers were separated and the aqueous layer was extracted with EtOAc (3 x 15 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 12-10 as a yellow oil and a 2:1 mixture of diastereomers, which was used without further purification.