1.1: ozone / CH2Cl2; methanol / -78 °C 1.2: 73 percent / Me2S / CH2Cl2; methanol / 3 h / 20 °C 2.1: KHMDS; 18-crown-6 / tetrahydrofuran / 0.5 h / -78 °C 2.2: tetrahydrofuran / 3 h / -78 °C 3.1: O3 / CH2Cl2; methanol 3.2: NaBH4 / propan-2-ol 4.1: KOH / methanol View Scheme

1.1: ozone / CH2Cl2; methanol / -78 °C 1.2: 73 percent / Me2S / CH2Cl2; methanol / 3 h / 20 °C 2.1: KHMDS; 18-crown-6 / tetrahydrofuran / 0.5 h / -78 °C 2.2: tetrahydrofuran / 3 h / -78 °C 3.1: O3 / CH2Cl2; methanol 3.2: NaBH4 / propan-2-ol 4.1: KOH / methanol View Scheme

1: With ozone in dichloromethane T=-78°C; 2: With triethylamine in dichloromethane T=-78 - 20°C; 10 h;