[C:1]([O:4][C:5](=[O:7])[CH3:6])(=O)[CH3:2].N1C=CC=CC=1.[CH2:14](O)[CH2:15][CH2:16][CH2:17][CH2:18][CH2:19][CH2:20][CH2:21]/[CH:22]=[CH:23]\[CH2:24]/[CH:25]=C/C.CCOC(C)=O>C(Cl)Cl.C(OCC)C>[C:5]([O:4][CH2:1][CH2:2][CH2:25][CH2:24][CH2:23][CH2:22][CH2:21][CH2:20]/[CH:19]=[CH:18]\[CH2:17]/[CH:16]=[CH:15]/[CH3:14])(=[O:7])[CH3:6]
Acetic anhydride (3.1 mmol, 0.29 mL), then pyridine (1.8 mmol, 0.14 mL), were added sequentially to alcohol 15 (1.5 mmol, 0.32 g) in CH2Cl2 (3 mL), and stirred at room temperature for 18 hours. The mixture was diluted with diethyl ether, washed with saturated aqueous NaHCO3, then brine, dried with Na2SO4, and concentrated. Flash chromatography of the residue (SiO2, 10% EtOAc in hexanes) provided 16 (0.34 g, 89% yield, 88% Z as determined by 1H-NMR) as a colorless oil; 1H NMR (CDCl3): δ 5.31-5.49 (4H, m), 4.05 (2H, t, J=6.8 Hz), 2.72 (2H, m), 2.05 (3H, s), 2.02 (2H, m), 1.65 (2H, m), 1.61 (2H, m), 1.24-1.38 (11H, m); 13C NMR (CDCl3): δ 171.3, 130.4, 129.6, 127.7, 125.1, 64.7, 30.4, 29.6, 29.4, 29.2 (2C), 28.6, 27.1, 25.9, 21.0, 17.9; HRMS (FAB): 251.2000, [C16H28O2−H]+ requires 251.2011.
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