1: 96 percent / DBU / 3 h / 140 °C 2: 99 percent / NaOH / ethanol / 16 h / 20 °C View Scheme

1: 96 percent / DBU / 3 h / 140 °C 2: 99 percent / NaOH / ethanol / 16 h / 20 °C 3: thionyl chloride; DMF / 20 - 80 °C 4: 8.1 g / n-BuLi / tetrahydrofuran; hexane / 1 h / -65 °C View Scheme

1: 96 percent / DBU / 3 h / 140 °C 2: 99 percent / NaOH / ethanol / 16 h / 20 °C 3: thionyl chloride; DMF / 20 - 80 °C View Scheme

1,8-diazabicyclo[5.4.0]undec-7-ene T=140°C; 3 h;