1: 80.2 percent / triethylamine / dimethylformamide; dioxane / 4 °C 2: hydrogen bromide / acetic acid 3: 55.1 percent / triethylamine / dimethylformamide; tetrahydrofuran / 4 °C 4: hydrogen bromide / acetic acid 5: 78.9 percent / triethylamine / dimethylformamide / Ambient temperature 6: hydrogen bromide / acetic acid 7: 66.5 percent / pyridine, triethylamine / 4 °C View Scheme