1: iso-butyronitrile With lithium diisopropyl amide in tetrahydrofuran T=-78 - 0°C; 1 h; 2: Methanesulfonic acid (E)-hepta-2,6-dienyl ester in dichloromethane T=-78 - 20°C;

1.1: oxalyl chloride; DMSO; Et3N / CH2Cl2 / 0.5 h / -78 °C 2.1: 52 g / CH2Cl2 / 2 h / 20 °C 3.1: 97 percent / DIBAL-H / CH2Cl2 / 3 h / -78 °C 4.1: Et3N / CH2Cl2 / 0 °C 5.1: LDA / tetrahydrofuran / 1 h / -78 - 0 °C 5.2: 3.6 g / CH2Cl2 / -78 - 20 °C View Scheme

1.1: 52 g / CH2Cl2 / 2 h / 20 °C 2.1: 97 percent / DIBAL-H / CH2Cl2 / 3 h / -78 °C 3.1: Et3N / CH2Cl2 / 0 °C 4.1: LDA / tetrahydrofuran / 1 h / -78 - 0 °C 4.2: 3.6 g / CH2Cl2 / -78 - 20 °C View Scheme

1.1: Et3N / CH2Cl2 / 0 °C 2.1: LDA / tetrahydrofuran / 1 h / -78 - 0 °C 2.2: 3.6 g / CH2Cl2 / -78 - 20 °C View Scheme

1.1: 97 percent / DIBAL-H / CH2Cl2 / 3 h / -78 °C 2.1: Et3N / CH2Cl2 / 0 °C 3.1: LDA / tetrahydrofuran / 1 h / -78 - 0 °C 3.2: 3.6 g / CH2Cl2 / -78 - 20 °C View Scheme