A mixture of the title compound from Step A (2.1 g, 3.75 mmol), n-pentyl nitrite (0.66 g, 5.62 mmol) and I2 (1.24 g, 4.87 mmol) in chloroform (20 mL) was stirred at 80° C. for 1 h. The mixture was cooled, and the solvent was diluted with CH2Cl2. The mixture was washed with Na2S2O3 (5 mL), and with brine (5 mL), dried (Na2SO4), filtered and the solvent was evaporated under reduced pressure. The residue was purified by column chromatography on silica gel Biotage 40M, eluting with EtOAc/hexane (10/90) to give the title compound as a yellow gum. 1H NMR (CDCl3, 500 MHz) δ 8.41 (s, 1H), 7.92 (s, 1H), 7.78 (s, 2H), 7.77 (m, 1H), 7.35 (m, 1H), 7.22 (m, 1H), 5.76 (d, J=8.5 Hz, 1H), 4.91 (d, J=17 Hz, 1H), 4.45 (m, 1H), 4.06 (d, J=17.5 Hz, 1H), 2.64 (s, 3H), 0.76 (d, J=7 Hz, 3H). LCMS=672.1 (M+H)+.
