To a stirred and cooled (0° C.) solution of 0.140 g (0.41 mmol) of the product of Step D dissolved in 2 mL of CH2Cl2 was added 0.170 g (0.51 mmol) of carbon tetrabromide and 0.135 g (0.51 mmol) of triphenylphosphine. After the addition the reaction mixture was allowed to warm to room temperature and was stirred overnight. The mixture was then evaporated in vacuo and purified on a silica gel flash chromatography column eluted with 15% ethyl acetate/hexane to afford 0.130 g (78%) of the title compound.
