Reaction Steps
According to the method of M. L. Gillaspy, B. A. Lefke, W. A. Hada, D. J. Hoover, Tetrahedron Letters 1995, 7399-7402, Cpd 30 (50 mg, 0.085 mmol), acetic acid (0.050 mL, 0.87 mmol), 3 Å molecular sieves (230 mg), [(1-ethoxycyclopropyl)oxy]trimethylsilane (0.102 mL, 0.51 mmol) were combined in methanol (4 mL) at rt. Sodium cyanoborohydride (24 mg, 0.38 mmol) was added and the reaction mixture was heated at reflux overnight, cooled to RT, filtered, and concentrated. The residue was dissolved in EtOAc (25 mL), washed with 2 N sodium hydroxide solution (2×10 mL) and brine (2×10 mL), dried (Na2SO4), concentrated, and purified by reversed phase HPLC [Phenomenex, Kromasil C18, 10μ, 110 Å, 250×50 mm, gradient elution with 20-90% acetonitrile (0.16% TFA) in water (0.2% TFA)] to yield Cpd 7 (12 mg, 19%) as a TFA salt. 1H NMR (300 MHz, CDCl3) δ 7.63 (d, J=7.4 Hz, 1H), 7.59 (d, J=4 Hz, 1H), 7.52 (d, J=4 Hz, 1H), 7.47 (t, J=7.8 Hz, 1H), 7.18 (d, J=7.8 Hz, 1H), 7.13 (t, J=4 Hz, 1H), 6.99 (br d, J=8.2 Hz, 1H), 6.92 (br s, 1H), 6.86 (d, J=8.2 Hz, 1H), 5.56 (br t, J=7.5 Hz, 1H), 4.34 (d, J=17 Hz, 1H), 3.93 (buried d, J=17 Hz, 1H), 3.88 (s, 3H), 3.86 (s, 3H), 3.7-2.9 (m, 11H), 2.66 (s, 3H), 2.5-2.0 (m, 6H), 1.7 (m, 2H); LC/MS (ES+) m/z 625.3 (M+1).
