methanol; potassium carbonate; tetrakis(triphenylphosphine) palladium(0); AgCl in N,N-dimethyl-formamide T=40°C; Sonogashira cross-coupling; 1 h;

n-butyllithium in hexane T=-78 - -40°C; Fritsch-Buttenberg-Wiechell rearrangement; 0.5 h;

1.1: n-BuLi / tetrahydrofuran; hexane / 2 h / -78 - 20 °C 1.2: 54 percent / tetrahydrofuran; hexane / -78 - 20 °C 2.1: 59 percent / manganese dioxide / CH2Cl2 / 20 °C 3.1: 58 percent / PPh3 / CH2Cl2 / 20 °C 4.1: 72 percent / n-BuLi / hexane / 0.5 h / -78 - -40 °C View Scheme

1: 59 percent / manganese dioxide / CH2Cl2 / 20 °C 2: 58 percent / PPh3 / CH2Cl2 / 20 °C 3: 72 percent / n-BuLi / hexane / 0.5 h / -78 - -40 °C View Scheme

1: 58 percent / PPh3 / CH2Cl2 / 20 °C 2: 72 percent / n-BuLi / hexane / 0.5 h / -78 - -40 °C View Scheme