sodium tetrahydroborate Ambient temperature;

1: 1.) conc. HCl, NaNO2, 2.) CuCl2 / 1.) H2O, 10 deg C, 0.5 h, 2.) H2O, 40 deg C, 20 h 2: NH2OH*HCl / ethanol; H2O / 1 h 3: POCl3 / benzene / 1.5 h / Heating 4: 91 percent / NaBH4 / Ambient temperature View Scheme

1: 1.) conc. HCl, NaNO2, 2.) CuCl2 / 1.) H2O, 10 deg C, 0.5 h, 2.) H2O, 40 deg C, 20 h 2: NH2OH*HCl / ethanol; H2O / 1 h 3: POCl3 / benzene / 1.5 h / Heating 4: 91 percent / NaBH4 / Ambient temperature View Scheme

1: NH2OH*HCl / ethanol; H2O / 1 h 2: POCl3 / benzene / 1.5 h / Heating 3: 91 percent / NaBH4 / Ambient temperature View Scheme

1: POCl3 / benzene / 1.5 h / Heating 2: 91 percent / NaBH4 / Ambient temperature View Scheme