1.1: CuCN / diethyl ether / 0.25 h / 0 °C 1.2: 97 percent / diethyl ether / 20 h / 0 °C 2.1: 94 percent / 4-dimethylaminopyridine; triethylamine / CH2Cl2 / 20 °C View Scheme

1: 1-(trimethylsilyl)-1-propyne With n-butyllithium; N,N,N',N,-tetramethylethylenediamine in tetrahydrofuran T=0°C; 0.75 h; 2: With copper(l) iodide in tetrahydrofuran T=-78°C; 0.5 h; 3: (4E)-5-iodo-5-trimethylsilanyl-pent-4-en-1-ol With 4-(N,N-dimethlyamino)pyridine in tetrahydrofuran T=-20 - 20°C;