[CH:1]([O:8][CH2:9][CH3:10])([O:5][CH2:6][CH3:7])OCC.B(F)(F)F.CCOCC.[Br:20][C:21]1[CH:29]=[CH:28][C:27]([O:30][CH3:31])=[C:26]2[C:22]=1[CH2:23][CH2:24][C:25]2=[O:32].C(N(C(C)C)CC)(C)C>C(Cl)Cl>[CH2:9]([O:8][CH:1]([O:5][CH2:6][CH3:7])[CH:24]1[CH2:23][C:22]2[C:26](=[C:27]([O:30][CH3:31])[CH:28]=[CH:29][C:21]=2[Br:20])[C:25]1=[O:32])[CH3:10]Triethyl orthoformate (16.5 ml) was cooled to -30° C. and 15.0 ml BF3.Et2O in 50 ml methylene chloride was added. The reaction was warmed to 0° C. for 15 min, and then cooled to -78° C. To the reaction was added 12.05 g of the product from Example 34 in 50 ml methylene chloride, followed by dropwise addition of 19.4 ml diisopropyl ethyl amine. The reaction was then warmed to -15° C. for 2 h, then quenched in 5% NaHCO3 solution and extracted with methylene chloride. The organic extracts were washed with brine, dried (MgSO4), and the solvent removed. The crude product was triturated with cold hexane, and the crystalline product collected to yield 14.60 g of a white solid, mp: 76-8° C. NMR (CDCl3) δ 1.05 (t, 3H), 1.27 (t, 3H), 3.03 (m, 2H), 3.30 (m, 1H), 3.43-3.80 (m, 4H), 3.95 (s, 3H), 5.00 (d, 1H), 6.71 (d, 1H), 7.63 (d, 1H).
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