1: 60 percent / triethylamine / diethyl ether / 1 h / Ambient temperature 2: 72 percent / dimethylformamide / 56 h / 100 °C / The effect of various reaction time, solvents, reaction temperature, and reagents rate was studied. View Scheme

in N,N-dimethyl-formamide T=100°C; 56 h;