1: With ozone in dichloromethane T=-78°C; 2: With triethylamine in dichloromethane T=-78 - 20°C;

1.1: tetrahydrofuran / 0.17 h / 20 °C 1.2: 66 percent / triethylamine / tetrahydrofuran / 0.5 h / 20 °C 2.1: ozone / CH2Cl2 / -78 °C 2.2: 86 percent / triethylamine / CH2Cl2 / -78 - 20 °C View Scheme