To a solution of 38.3 g of (2Z)-4-hydroxy-2-[4-(methylsulfonyl)phenyl]-3-phenylbut-2-enyl acetate in 500 mL of dichloromethane, 47 g of Dess-Martin reagent was added and the resulted mixture was stirred at rt for 2 hr. Then 2 mL of water was added and the resulted mixture was stirred at rt for 1 hr. Then the mixture was filtered and evaporated. The crude thus obtained was dissolved in a solvent mixture of 200 mL of THF with 200 mL of t-BuOH. To the resulting mixture, 30 mL of 2-methyl-2-butene was added and followed by the addition of 200 mL of 1.2 M of phosphoric acid and 200 mL of 1 M of NaClO2. The resulting mixture was stirred at rt for 30 min. The organic phase was separated and the aqueous phase was extracted with EtOAc. The organic phase was combined, dried over Na2SO4, filtered, and then evaporated. The crude was purified by recrystallization from ether to afford 37 g of the titled compound as white solid. 1H NMR (acetone-d6, 500 M Hz): δ 7.76 (d, 2H), 7.43 (d, 2H), 7.18–7.12 (m, 3H), 7.12–7.08 (m, 2H), 5.24 (s, 2H), 3.05 (s, 3H), 1.88 (s, 3H).
