1.1: sodium naphthalenide / tetrahydrofuran / -25 °C 1.2: 82 percent / triethylamine / tetrahydrofuran / 4 h / -25 - 20 °C 2.1: Rose Bengal; oxygen / tetradeuteriomethanol / 0.5 h / Irradiation; acetone/dry ice cooling 3.1: TMSOTf / CH2Cl2 / 0.33 h / -78 °C 3.2: 1.39 mg / water; CSA / CH2Cl2 / 3 h / 20 °C View Scheme

Multi-step reaction with 2 steps 1.1: ozone / CH2Cl2; methanol / -78 - 20 °C1.2: 93 percent / dimethyl sulfide / CH2Cl2; methanol / 3 h / 20 °C2.1: 96 percent / trimethylsilyl triflate / CH2Cl2 / 16 h / -78 °C