“…The residue was purified by silica gel column chromatography (hexaneEtOAc, 1:1) to give the ditosyl derivative (153 mg, 96%). To a solution of the product (153 mg, 0.192 mmol) in dry THF (15 mL) was added TBAF (1.0 M in THF, 0.4 mL, 0.4 mmol) at room temperature, and the mixture was stirred at 40°C for 2 h. The reaction mixture was quenched with saturated aqueous NH 4 Cl, washed with brine, dried, and concentrated. The crude product was purified by silica gel column chromatography (hexane-EtOAc, 3:7) to afford diepoxide 16 (37.6 mg, 87%).…”