反应详情

温度

55 °C

To the hydroxy ester from Step 16 (9.02 g, 17.1 mmol) in anhydrous methanol (60 mL) under nitrogen was added pyridine (50 μL) followed by pyridinium p-toluenesulfonate (1.1 g, 4.3 mmol). The reaction mixture was stirred 3.5 hours at 55° C., then at r.t. overnight before concentrating in vacuo. The residue was diluted with EtOAc (500 mL) and washed with H2O, saturated aq. NaHCO3, NaH2PO4 buffer (pH=4.5) and with brine. After drying over MgSO4 and evaporation of the solvents, the product was purified by flash chromatography (40% to 60% EtOAc in hexanes) giving 6.85 g (91%) of the title compound.

1. concentrationat r.t. overnight before concentrating in vacuo
2. additionThe residue was diluted with EtOAc (500 mL)
3. washwashed with H2O, saturated aq. NaHCO3, NaH2PO4 buffer (pH=4.5) and with brine
4. dry with materialAfter drying over MgSO4 and evaporation of the solvents
5. customthe product was purified by flash chromatography (40% to 60% EtOAc in hexanes)