1: 73 percent / zinc; copper / acetonitrile / 72 h / 156 °C 2: 58 percent / sodium hydroxide / 2.5 h / Heating 3: 58 percent / sodium hydride / heptane / 2.5 h / Heating 4: 80 percent / hydrogen peroxide; vanadium(V) oxide / dimethylformamide / 4.5 h / 57 °C View Scheme