hydrogenchloride in hexane 36 h; Heating; Yield given;

1: 99 percent / NEt3 / diethyl ether / 16 h 2: 99 percent / trimethylsilyl triflate / tetrahydrofuran / 4 h View Scheme

1: 64 percent / 4-(dimethylamino)pyridine / dimethylformamide / 12 h / Ambient temperature 2: 91.4 percent / tetrahydrofuran; diethyl ether / 3 h / -78 °C 3: 96.1 percent / conc. HCl / CH2Cl2 / 0.5 h / Ambient temperature View Scheme

Multi-step reaction with 4 steps 2: 91 percent3: 96 percent / acid  

With  hydrogenchloride in  dichloromethane; water  

Multi-step reaction with 2 steps 1: 64 percent / 4-(dimethylamino)pyridine / dimethylformamide / 12 h / Ambient temperature2: 91.4 percent / tetrahydrofuran; diethyl ether / 3 h / -78 °C