trifluoroacetic acid; palladium diacetate in dichloromethane T=50°C; 24 h;

1.1: n-butyllithium / tetrahydrofuran; hexane / 0.5 h / -78 °C 1.2: 80 percent / tetrahydrofuran; hexane / -78 - 20 °C 2.1: 59 percent / trifluoroacetic acid / palladium(II) acetate / CH2Cl2 / 24 h / 50 °C View Scheme