Ni(PPh3)4 in toluene T=60 - 100°C; 5 h;

Multi-step reaction with 4 steps 1: 92 percent / benzene / 1 h / 25 °C2: 98 percent / ethyl chloroformate, triethylamine / tetrahydrofuran / 1 h / -12 °C3: tetrahydrofuran / 1 h / -60 °C4: 1.) NaH / 1.) THF, mineral oil, 2.) THF, 12 h, r.t.