1: 7-ethynyl-7,10-dimethyl-undeca-1,9-diene With n-butyllithium in tetrahydrofuran; hexane T=-78°C; 1.5 h; 2: methyl chloroformate in tetrahydrofuran; hexane T=-78 - 20°C;

1.1: 84 percent / K2CO3 / methanol / 3.5 h 2.1: n-butyllithium / hexane; tetrahydrofuran / 1.5 h / -78 °C 2.2: 92 percent / hexane; tetrahydrofuran / -78 - 20 °C View Scheme

1.1: DIBAL-H / diethyl ether; hexane / -70 - 20 °C 2.1: 84 percent / K2CO3 / methanol / 3.5 h 3.1: n-butyllithium / hexane; tetrahydrofuran / 1.5 h / -78 °C 3.2: 92 percent / hexane; tetrahydrofuran / -78 - 20 °C View Scheme

1.1: LiHMDS / tetrahydrofuran / 1 h / 20 °C 2.1: DIBAL-H / diethyl ether; hexane / -70 - 20 °C 3.1: 84 percent / K2CO3 / methanol / 3.5 h 4.1: n-butyllithium / hexane; tetrahydrofuran / 1.5 h / -78 °C 4.2: 92 percent / hexane; tetrahydrofuran / -78 - 20 °C View Scheme