Reaction Steps
Acetonide 10 (534 mg; 1.33 mmol) was dissolved in EtOH (10 mL) and 12.4 ml of ethanolic sodium ethoxide solution (0.05M) was added dropwise over period 1 min. After 5 min of stirring at room temperature reaction mixture was quenched by addition of 1 g of silica and then filtered and evaporated. Chromatography [ethyl acetate→ethyl acetate-ethanol (1:1), 5 g silica] of residue afforded 432 mg (94%) of allylalcohol 12 as white solid: m.p.=177-178° C. (ethyl acetate-hexane); Rf=0.2 (ethyl acetate); [α]20D=−9.14 (c=1, CHCl3); IR (KBr, cm−1) ν 3341, 2926, 2854, 2360, 2326, 1726, 1680, 1654, 1626, 1530, 1460, 1319, 1295, 1249, 1165, 1127, 1091, 1046, 1025, 992, 946, 908, 863, 782, 755, 735, 644, 607, 590, 571, 543, 491, 460, 437; 1H NMR (CDCl3, 600 Mhz) δ 7.35 (d, J=5.8 Hz, 1H), 6.83 (dd, J=2.4, 2.4 Hz, 1H), 5.07 (bs, 1H), 4.92 (d, J=7.9 Hz, 1H), 4.36-4.29 (m, 1H), 4.27-4.16 (m, 2H), 3.85-3.83 (m, 1H), 3.77-3.73 (m, 1H), 2.84 (dd, 1H, J=17.4, 5.1 Hz, 1H), 2.21 (dddd, J=17.4, 11.0, 2 x≈3 Hz, 1H), 2.03 (s, 3H), 1.47 (s, 9H), 1.30 (t, J=7.2 Hz, 3H); 13C NMR (CDCl3, 150 Mhz) δ 173.61, 165.86, 157.64, 139.05, 127.65, 80.87, 73.60, 61.05, 60.55, 48.05, 30.83, 28.23, 23.09, 14.17; MS (FAB+) m/z %: 343 (M++H), 287(100), 243(25), 208 (30); HRMS. Calcd for C16H27N2O6: 343.18691. Found: 343.18417; Anal. Calcd for C16H27N2O6: C, 56.13; H, 7.65; N, 8.18. Found C, 56.31; H, 7.83; N, 8.17.
