sodium tetrahydroborate in ethanol 48 h;

1: 90 percent / NaBH4 / ethanol / 48 h 2: 65 percent / NaHCO3 / H2O / 1.5 h / Ambient temperature 3: 86 percent / PCC / CH2Cl2 / 3 h / Ambient temperature 4: 55 percent / ammonium formate / Pd/C / methanol / 0.5 h / Heating View Scheme