1: 84 percent / DIBALH / CH2Cl2; hexane / 0.33 h / -60 °C 2: 94 percent / (COCl)2; DMSO; Et3N / CH2Cl2 / -60 - -20 °C View Scheme

(-)-10-CSA in methanol; dichloromethane T=0°C; 1.5 h;

1: diisobutylaluminium hydride / dichloromethane / 3 h / 0 °C / Inert atmosphere 2: water; acetic acid / tetrahydrofuran / 12 h / 23 °C / Inert atmosphere 3: 2,3-diphenylcyclopropenone; trifluoromethanesulfonic anhydride / dichloromethane / 3 h / 23 °C / Inert atmosphere View Scheme

1: With diisobutylaluminium hydride in tetrahydrofuran T=0°C; 2 h; Inert atmosphere; 2: With hydrogenchloride in methanol; water T=25 - 28°C; 1 h; Inert atmosphere;