sodium cyanoborohydride; trifluoroacetic acid in tetrahydrofuran Ambient temperaturepH 4-5, indicator Bromocresol Green or pH 5-6, indicator Chlorophenol Red;

1: 88 percent / Sulfuryl chloride / toluene; diethyl ether / 2 h / 0 °C 2: 78 percent / 29 percent NH4OH/H2O / CH2Cl2 / 0 °C 3: 98 percent / Pyridinium p-toluenesulfonate, (PPTS)/anhydr. MgSO4 / CH2Cl2 / 2 h / Ambient temperature 4: 100 percent / NaBH3CN/1percent CF3COOH / tetrahydrofuran / Ambient temperature; pH 4-5, indicator Bromocresol Green or pH 5-6, indicator Chlorophenol Red View Scheme

1: 78 percent / 29 percent NH4OH/H2O / CH2Cl2 / 0 °C 2: 98 percent / Pyridinium p-toluenesulfonate, (PPTS)/anhydr. MgSO4 / CH2Cl2 / 2 h / Ambient temperature 3: 100 percent / NaBH3CN/1percent CF3COOH / tetrahydrofuran / Ambient temperature; pH 4-5, indicator Bromocresol Green or pH 5-6, indicator Chlorophenol Red View Scheme

1: 98 percent / Pyridinium p-toluenesulfonate, (PPTS)/anhydr. MgSO4 / CH2Cl2 / 2 h / Ambient temperature 2: 100 percent / NaBH3CN/1percent CF3COOH / tetrahydrofuran / Ambient temperature; pH 4-5, indicator Bromocresol Green or pH 5-6, indicator Chlorophenol Red View Scheme