反应详情

温度

55 °C

To the hydroxy ester from Step 14 (9.02 g, 17.1 mol) in anhydrous MeOH (60 mL) under nitrogen was added pyridine (50 μL) followed by PPTS (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 residue was purified by flash chromatography (40% to 60% EtOAc in hexanes) giving 6.85 g (91%) of the title compound. 1H NMR (CD3COCD3): δ5 7.41 (2H, m), 7.27 (3H, m), 7.09 (3H, m), 4.63 (2H, d), 4.19 (1H, t), 3.95 (1H, t), 3.88 (1H, s), 3.57 (3H, s), 3.1 (1H, ddd), 2.8 (1H, ddd), 2.5 (2H, s), 2.4 (2H, d), 2.17 (2H, m), 1.52 (6H, s), 0.52-0.35 (4H, m).

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 residue was purified by flash chromatography (40% to 60% EtOAc in hexanes)