Reaction Steps
To a mixture of 7b (0.5 g, 1.78 mmol) in CH2Cl2 (20 mL) was added Dess-Martin periodinane (1.2 g, 2.85 mmol). The mixture was stirred at rt for 3 h and then poured into a well-stirred mixture of satd. Na2S2O3 (10 mL) and satd. NaHCO3 (10 mL). The layers were separated after 30 min. The aqueous layer was extracted 3 times with diethyl ether. The combined organic extracts were washed with satd. NaHCO3, brine, dried over MgSO4 and concentrated under vacuum to give the crude aldehyde 8b (0.47 g, 89%) as pale yellow oil. The crude product was sufficiently pure for the subsequent reaction. IR (CH2Cl2, NaCl,cm−1) 3380, 3057, 2982, 1763, 1655, 1596, 1422, 1264, 895, 735, 547; 1H NMR (300 MHz, CDCl3) δ0.82 (t, J=7.4 Hz, 3H), 1.91 (m, 2H), 2.85 (d, J=15.9 Hz, 1H), 3.10 (d, J=15.9 Hz, 1H), 3.41 (s, 3H), 3.96 (s, 3H), 4.74 (s, 2H), 4.98 (q, J=10.9 Hz, 2H), 6.74 (d, J=5.5 Hz, 1H), 8.06 (d, J=5.5 Hz, 1H), 9.73 (s, 1H); 13C NMR (75 MHz, CDCl3) δ7.94, 36.42, 54.23, 55.31, 55.99, 60.93, 77.90, 96.45, 115.82, 117.41, 146.55, 155.59, 163.85, 202.18; HRMS (EI) m/z calcd for C14H22NO5 (M+H) 284.1498, found 284.1498; LRMS (ED) 284(M+H, 15), 265(25), 192(20), 178(72), 148(24), 84(100), 57(26); [α]D23=−11.5 (c=0.125, CH2Cl2).
