1: 67 percent / 80percent hydrazine hydrate, KOH / bis-(2-hydroxy-ethyl) ether / 3 h / Heating 2: 1.) t-butyllithium, Cu2Br2-Me2S, 2.) O2 / 1.) hexane, THF, -78 deg C, 1 h, 2.) from -78 deg C to RT, 1 h View Scheme

1: 67 percent / 80percent hydrazine hydrate, KOH / bis-(2-hydroxy-ethyl) ether / 3 h / Heating 2: 1.) t-butyllithium, Cu2Br2-Me2S, 2.) O2 / 1.) hexane, THF, -78 deg C, 1 h, 2.) from -78 deg C to RT, 1 h View Scheme

1: 67 percent / 80percent hydrazine hydrate, KOH / bis-(2-hydroxy-ethyl) ether / 3 h / Heating 2: 1.) t-butyllithium, Cu2Br2-Me2S, 2.) O2 / 1.) hexane, THF, -78 deg C, 1 h, 2.) from -78 deg C to RT, 1 h View Scheme

With  dipyridinium dichromate in  dichloromethane 0.166667 h;