To a -50° C. solution of 5,5-dimethyl-3-(3-fluorophenyl)-4-(4-(methylsulfonyl)phenyl)-2-(5H)-furanone (30 g, 83.3 mmol) in 500 mL of THF was added dropwise a solution of DIBAL (90 mL, 1.5M in toluene) over a period of 15 min. The reaction mixture was allowed to warm to -10° C. over a period of 1 h, then treated with 20 mL of acetone, followed by 50 mL of methanol. The reaction mixture was then warmed to -20° C. and treated with aqueous potassium sodium tartrate (20%, 400 mL). After stirring at r.t. for 1 h, the product was extracted with 500 mL of 2:1 EtOAc/hexane, dried over Na2SO4, filtered and concentrated. The crude product was swished with 2:1 hexane/EtOAc to give 24 g of purified title compound as a white solid.
