1.1: 4.36 g / NaH / tetrahydrofuran 2.1: Cp2ZrCl2; nBuLi / tetrahydrofuran; hexane / 0.5 h / Heating 2.2: 70 percent / tetrahydrofuran; hexane / -78 - 20 °C View Scheme

2,3-dicyano-5,6-dichloro-p-benzoquinone in diethyl ether T=18°C; 24 h;