1: 1-cyclohexenylacetylene With n-butyllithium in tetrahydrofuran T=-78 - 0°C; 1 h; 2: formaldehyd T=-78 - 20°C; Further stages.;

toluene-4-sulfonic acid in benzene 30 h; Heating;

copper(l) iodide; diethylamine; bis-triphenylphosphine-palladium(II) chloride in tetrahydrofuran Sonogashira coupling; 16 h; Heating;

1: 90 percent / triethylamine / Pd(PPh3)4; CuI / 12 h 2: 93 percent / PPh3 / CH2Cl2 / 2 h / 0 °C 3: 83 percent / LDA / tetrahydrofuran / 2 h / 28 °C 4: 75 percent / p-toluenesulfonic acid / benzene / 30 h / Heating View Scheme

1: 81 percent / PBr3 / CHCl3 / 8 h 2: 90 percent / triethylamine / Pd(PPh3)4; CuI / 12 h 3: 93 percent / PPh3 / CH2Cl2 / 2 h / 0 °C 4: 83 percent / LDA / tetrahydrofuran / 2 h / 28 °C 5: 75 percent / p-toluenesulfonic acid / benzene / 30 h / Heating View Scheme

1: 83 percent / LDA / tetrahydrofuran / 2 h / 28 °C 2: 75 percent / p-toluenesulfonic acid / benzene / 30 h / Heating View Scheme

1: 93 percent / PPh3 / CH2Cl2 / 2 h / 0 °C 2: 83 percent / LDA / tetrahydrofuran / 2 h / 28 °C 3: 75 percent / p-toluenesulfonic acid / benzene / 30 h / Heating View Scheme