The reaction was stirred for 30 min and then allowed to warm to room temperature and stirred for a further 4 h. The reaction was quenched with 2 N HCl and stirred for 10 min. After separation the aqueous phase was neutralized to pH 8 with NaOH and extracted with CH2Cl2 (3 x 20 mL). The organic layers were combined, washed with water, brine and dried over MgSO4. The organic phase was concentrated in vacuo to afford the crude product. Products were purified by flash chromatography using solvent gradient of 0:100 → 50:50 cyclohexane:EtOAc over 20 min.