1: potassium t-butoxid, 18-Crown-6 / benzene / 0.5 h / Ambient temperature 2: sodium borohydride / propan-2-ol / 4 h / Heating 3: PBr3, LiBr, 2,4,6-collidine / 3 h / -40 - 0 °C 4: 1.) ZnBr, 2.) DBU / 1.) ether, -40 deg C to 0 deg C, 2 h, 2.) 50 deg C, 2 h View Scheme

Multi-step reaction with 2 steps 1: potassium t-butoxid, 18-Crown-6 / benzene / 0.5 h / Ambient temperature2: sodium borohydride / propan-2-ol / 4 h / Heating  

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