1: 92 percent / molecular sieves 5A, BF3*Et2O / CH2Cl2 / 12 h / Ambient temperature 2: 75 percent / H2 / Raney nickel / propan-2-ol / 70 °C 3: 1N aq. HCl / methanol / Ambient temperature View Scheme

With  L-Selectridereg;  

Multi-step reaction with 2 steps 1: ZnCl2*Et2O / tetrahydrofuran / -20 °C2: 96 percent / L-selectride  

With  boron trifluoride; ethane-1,2-dithiol; Ra-Ni  Yield given. Multistep reaction;