反应详情

A solution of compound 4 (2.80 g, 4.90 mmol) in acetic anhydride (5 ml) and pyridine (5 ml) was stirred at room temperature for 6 hours. The solution was concentrated and the oil was dissolved in 4:3:1 glacial acetic acid-ethanol-water (20 ml) and heated on a steam bath. After 2 hours the solution was concentrated and the residue was chromatographed on silica gel using 10% ethylacetatehexane to afford 1.53 g (84%) of the title compound (6) as a waxy white solid, m.p. 33°. NMR (CDCl3, (CH3)4Si); δ0.90 (t, 3H, J=6 Hz, --CH3), 1.25 (s, 26H, --CH2 --), 1.54 (m, 2H, --OCH2CH2R), 2.03 (s, 3H, CH3), 2.16 (m, 1H, CH), 2.54 (t, 1H, J=6.5 Hz, --OH), 3.41 (t, 3H, J=6.5 Hz, --OCH2R), 3.53, 3.56 (ABX, 2H, JAB =8.5, /J 5 Hz, --CH2OR), 3.73 (t, 2H, J=5 Hz, CH2OH), 4.18 (d, 2H, J=6.5 Hz, CH2OAc).

1. concentrationThe solution was concentrated
2. dissolutionthe oil was dissolved in 4:3:1 glacial acetic acid-ethanol-water (20 ml)
3. temperatureheated on a steam bath
4. concentrationAfter 2 hours the solution was concentrated
5. customthe residue was chromatographed on silica gel using 10% ethylacetatehexane