1: 6-ethynyl-undeca-1,10-diene With n-butyllithium in tetrahydrofuran T=-78°C; 2: methyl chloroformate in tetrahydrofuran T=-78 - 20°C;

1.1: 78 percent / K2CO3 / methanol / 20 °C 2.1: n-butyllithium / tetrahydrofuran / -78 °C 2.2: 76 percent / tetrahydrofuran / -78 - 20 °C View Scheme

1.1: 91 percent / DIBAL-H / diethyl ether / -78 °C 2.1: 78 percent / K2CO3 / methanol / 20 °C 3.1: n-butyllithium / tetrahydrofuran / -78 °C 3.2: 76 percent / tetrahydrofuran / -78 - 20 °C View Scheme

1.1: magnesium / tetrahydrofuran 1.2: 87 percent / tetrahydrofuran / 1 h / Heating 2.1: 4-DMAP; pyridine / 20 °C 3.1: 1.19 g / hexamethylphosphoric acid triamide / 20 °C 4.1: 91 percent / DIBAL-H / diethyl ether / -78 °C 5.1: 78 percent / K2CO3 / methanol / 20 °C 6.1: n-butyllithium / tetrahydrofuran / -78 °C 6.2: 76 percent / tetrahydrofuran / -78 - 20 °C View Scheme