1: 1.) 6N HCl; 2.) 1N NaOH / 1.) methanol, 24 h, reflux; 2.) 16 h 2: 90 percent / 4 N HCl / dioxane / 4 h / 80 °C 3: 99 percent / conc. aq. HCl / 16 h / 100 °C View Scheme