tetrabutyl ammonium fluoride in tetrahydrofuran 2 h;

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

1: tetrabutyl ammonium fluoride / tetrahydrofuran / 20 °C / |Inert atmosphere 2: chromium(VI) oxide; sulfuric acid / acetone; water / 0 - 20 °C View Scheme