1,8-diazabicyclo[5.4.0]undec-7-ene; 1,1'-carbonyldiimidazole in N,N-dimethyl-formamide T=40°C; 60 h;

1: 75 percent / K2CO3 / dimethylformamide / 20 h / Ambient temperature 2: 95 percent / NaOH / H2O / 12 h / 100 °C 3: 99 percent / CDI, DBU / dimethylformamide / 60 h / 40 °C View Scheme

1: 95 percent / NaOH / H2O / 12 h / 100 °C 2: 99 percent / CDI, DBU / dimethylformamide / 60 h / 40 °C View Scheme