77119-85-8

19901-50-9

77119-85-8

A toluene solution of DIBAL-H (1.0 M, 179 mL, 179 mmol) was added slowly and dropwise to a toluene-DCM (4:1, 1000 mL) solution of Compound 31c (25.0 g, 90 mmol) under stirring at -78 °C. The reaction was carried out under argon protection, followed by slow warming to room temperature and continuous stirring at this temperature for 1 hour. Immediately after completion of the reaction, methanol (200 mL) was added to quench the reaction. The reaction mixture was poured into 200 mL of 20% aqueous sodium potassium tartrate (Rochelle salt) and stirred at room temperature until the two phases were clearly separated. The organic layer was separated, concentrated under vacuum and the residue was purified by column chromatography (eluent: hexane/ethyl acetate = 2:1) to afford the target product compound 31d as a white solid (19.9 g, 89% yield).