hydrogenchloride; water in 1,4-dioxane T=20°C; 3 h; Inert atmosphere;

1: With oxalyl dichloride; dimethyl sulfoxide in dichloromethane T=-65°C; 0.25 h; Inert atmosphere; 2: With triethylamine in dichloromethane T=20°C; Swern oxidation; 2 h; Inert atmosphere;

1.1: toluene-4-sulfonic acid / toluene / 24 h / Reflux; Inert atmosphere 2.1: tetrahydrofuran / 0.33 h / -78 °C / Inert atmosphere 2.2: -78 - 0 °C / Inert atmosphere 2.3: 0 °C / Inert atmosphere 3.1: hydrogenchloride; water / 1,4-dioxane / 3 h / 20 °C / Inert atmosphere View Scheme

triethylsilane; trimethylsilyl trifluoromethanesulfonate in dichloromethane T=0 - 20°C; 6 h; Inert atmosphere;