diisobutylaluminium hydride in toluene T=-78°C; 2 h;

1: 86 percent / propionic acid / 130 °C 2: 79 percent / DIBAL-H / toluene / 2 h / -78 °C View Scheme

1: 97 percent / DIBAL-H / tetrahydrofuran / 2 h / -20 °C 2: 86 percent / propionic acid / 130 °C 3: 79 percent / DIBAL-H / toluene / 2 h / -78 °C View Scheme