To a solution of compound 7 (207 mg, 0.50 mmol) in THF (5 mL) were added water (0.05 mL), (1-ethoxy-1-cyclopropyloxy)-trimethylsilane (1174 mg, 1.0 mmol), acetic acid (0.55 mL) and sodium cyanoborohydride (1 mL, 1 M in THF, 1.0 mmol). The mixture was stirred at 60° C. overnight. The reaction mixture was concentrated and the residue was dissolved in ethyl acetate and washed with saturated NaHCO3 and brine then dried. The solvent was evaporated and the residue was purified by chromatography on silica gel eluting with CH2Cl2:methanol:NH4OH (400:10:1) to give compound 187 as a yellow solid (60 mg, 26% yield). 1H NMR (500 MHz, CDCl3) δ 9.08 (1H, s), 8.90 (1H, s), 8.51 (1 H, d, J=5 Hz), 8.39 (1H, d, J=10 Hz), 8.18 (1H, bs), 8.07 (1H, d, J=2 Hz), 7.84 (1H, d, J=5 Hz), 7.39 (1H, dd, J=10 Hz, J=2 Hz), 5.38 (1H, p, J=10 Hz), 3.17 (4H, q, J=5 Hz), 2.83 (2H, t, J=5 Hz), 2.42 (2H, m), 2.21-2.14 (4H, m), 1.88 (2H, m), 1.71 (1H, m), 0.53-0.46 (4H, m) ppm; LCMS-ESI (POS), M/Z, M+1: Found 454.2, Calculated 454.3.
