Bromides 3. A dry nitromethane solution of mercuric trifluoroacetate (0.45 M) was added to a stirred solution of diene 1 in nitromethane (0.3 M) at room temperature" under nitrogen. After 20 min, excess saturated aqueous potassium bromide was added and the resulting heterogeneous mixture was stirred efficiently at room temperature for 14 h. The mixture was extracted with methylene chloride, dried (MgS04), and concentrated to afford crude 3 as a ...