1: 90 percent / cc. aq. NH3 / methanol / 120 h / 20 °C 2: 51 percent / acetic acid / 4 h / Heating 3: 68 percent / conc. aq. NH3 / methanol / 24 h / 20 °C 4: 92 percent / DBU / dimethylformamide / 24 h / 20 °C View Scheme

1: 32 percent / DBU / dimethylformamide / 240 h / 20 °C 2: 80 percent / Ph3P; diisopropyl azodicarboxylate / dioxane / 24 h / 20 °C 3: 52 percent / conc. aq. NH3 / methanol / 24 h / 20 °C View Scheme