1,8-diazabicyclo[5.4.0]undec-7-ene; zinc dibromide 1.) ether, -40 deg C to 0 deg C, 2 h, 2.) 50 deg C, 2 h; Multistep reaction;

With  2,4,6-trimethyl-pyridine; phosphorus tribromide; lithium bromide T=-40 - 0°C; 3 h;   

Multi-step reaction with 2 steps 1: sodium borohydride / propan-2-ol / 4 h / Heating2: PBr3, LiBr, 2,4,6-collidine / 3 h / -40 - 0 °C  

Multi-step reaction with 3 steps 1: potassium t-butoxid, 18-Crown-6 / benzene / 0.5 h / Ambient temperature2: sodium borohydride / propan-2-ol / 4 h / Heating3: PBr3, LiBr, 2,4,6-collidine / 3 h / -40 - 0 °C