反应详情

A solution of 5 (4.75 g, 9.02 mmol) and p-toluenesulfonic acid in MeOH (50 mL) was stirred at rt for 12 h, then quenched with solid NaHCO3 and filtered. The filtrate was evaporated under vacuum and the residue was dissolved in ethyl acetate (50 mL). The ethyl acetate layer was washed with water (2×50 mL), brine (50 mL), dried over anhydrous Na2SO4 and concentrated under reduced pressure. The residue was purified by silica gel flash column chromatography using 50-60% ethyl acetate/hexane as eluent to afford alcohol 6 (2.35 g, 93%) as a colorless, viscous liquid. TLC:EtOAc/hexanes (1:1), Rf˜0.30; 1H NMR (400 MHz, 55/45 mixture of rotamers) δ 4.58-4.66 and 3.96-4.08 (m, 1H, rotamers), 3.56 and 3.70 (t, J=5.4 Hz, 2H, rotamers), 3.02 and 3.16 (t, J=5.2 Hz, 2H, rotamers), 2.38 and 2.26 (t, J=6.3 Hz, 2H, rotamers), 1.50-1.64 (m, 6H), 1.22-1.40 (m, 8H), 1.13 and 1.09 (d, J=7.5 Hz, 6H, rotamers), 0.84 (t, J=7.3 Hz, 3H); 13C NMR (100 MHz, 55/45 mixture of rotamers) δ 172.81, 62.66, 62.60, 48.41, 45.55, 43.56, 41.04, 34.08, 34.0, 32.46, 32.43, 31.86, 31.57, 29.40, 25.87, 25.70, 23.77, 23.73, 22.75, 21.57, 20.72, 14.26.

1. customquenched with solid NaHCO3
2. filtrationfiltered
3. customThe filtrate was evaporated under vacuum
4. dissolutionthe residue was dissolved in ethyl acetate (50 mL)
5. washThe ethyl acetate layer was washed with water (2×50 mL), brine (50 mL)
6. dry with materialdried over anhydrous Na2SO4
7. concentrationconcentrated under reduced pressure
8. customThe residue was purified by silica gel flash column chromatography