To a solution of the title compound of Step E (170 mg, 0.41 mmol) in dimethylformamide (4 ml) at 0° C. under nitrogen was added sodium hydride (60% dispersion in mineral oil, 41 mg, 1 mmol). The resulting slurry mixture was stirred at 0° C. for about 30 minutes and gradually became a brownish-yellow solution. To this solution at 0° C. was added methyl iodide (0.13 ml, 2 mmol). The resulting solution was warmed to room temperature and stirred for about 19 hours. The solution was diluted with 1N HCl (30 ml) and extracted with ethyl acetate (3×15 ml). The combined organic extracts were washed with 1N HCl (3×50 ml), brine, dried, filtered, and concentrated. The residue was purified by preparative TLC (50% ethyl acetate in hexanes) to afford the title compound (155 mg). MS (APCI+) Calc: 423.1, found: 424.0 (M+1).
