1: dimethylformamide / 3 h / 80 °C 2: 72 percent / Mg / Li2CuCl4 / tetrahydrofuran / 10 min, -78 deg C then 2 h, 0 deg C then 15 h, r.t. 4: KOH / methanol; hexane; H2O / 2 h / Ambient temperature View Scheme

1: dimethylformamide / 3 h / 80 °C 2: 72 percent / Mg / Li2CuCl4 / tetrahydrofuran / 10 min, -78 deg C then 2 h, 0 deg C then 15 h, r.t. 3: 94 percent / pyridinium-p-toluolsulfonate / ethanol / 1.5 h / 55 °C View Scheme

dilithium tetrachlorocuprate in tetrahydrofuran T=0°C; 2 h;

1: dimethylformamide / 3 h / 80 °C 2: 72 percent / Mg / Li2CuCl4 / tetrahydrofuran / 10 min, -78 deg C then 2 h, 0 deg C then 15 h, r.t. View Scheme

magnesium; copper(l) chloride in tetrahydrofuran