1: Et3N / 3 h / Ambient temperature 2: 73 percent / NaN3 / aq. ethanol / 8 h / Heating 3: 80 percent / tetra-n-butylammonium fluoride / tetrahydrofuran / 2 h View Scheme

1: Et3N / 3 h / Ambient temperature 2: 73 percent / NaN3 / aq. ethanol / 8 h / Heating 3: 80 percent / tetra-n-butylammonium fluoride / tetrahydrofuran / 2 h 4: Et3N / CH2Cl2 / 1.5 h / Ambient temperature 5: 75 percent / 1,2-dimethoxy-ethane / 0.5 h / Heating 6: 1) 55percent hydrazine hydrate, 2) conc. HCl / 1) MeOH, 2 h, reflux, 2) water, 1 h, reflux View Scheme