1: 98 percent / NaBH4 / methanol / 2 h 2: 79 percent / p-toluenesulfonic acid / benzene / 20 h / Heating 3: 73 percent / m-chloroperbenzoic acid / CH2Cl2 / 360 h / 4 °C / phosphate buffer (pH 8) View Scheme

sodium tetrahydroborate in methanol 2 h;