1: 1.) diethyl(methoxy)borane, 2.) sodium borohydride / 1.) THF, methanol, RT, 15 min, 2.) THF, methanol, a) -78 deg C, 4 h, b) from -78 deg C to RT, 8 h 2: 99 percent / p-toluenesulfonic acid / 2 h / Ambient temperature 3: 99 percent / tetrabutylammonium fluoride / tetrahydrofuran / 3 h / Ambient temperature 4: 85 percent / sodium metaperiodate, water / diethyl ether / 3 h / Ambient temperature View Scheme

1: 1.) diethyl(methoxy)borane, 2.) sodium borohydride / 1.) THF, methanol, RT, 15 min, 2.) THF, methanol, a) -78 deg C, 4 h, b) from -78 deg C to RT, 8 h 2: 99 percent / p-toluenesulfonic acid / 2 h / Ambient temperature 3: 99 percent / tetrabutylammonium fluoride / tetrahydrofuran / 3 h / Ambient temperature 4: 85 percent / sodium metaperiodate, water / diethyl ether / 3 h / Ambient temperature 5: 83 percent / sodium borohydride / methanol / 2 h / 0 °C View Scheme

1: 1.) diethyl(methoxy)borane, 2.) sodium borohydride / 1.) THF, methanol, RT, 15 min, 2.) THF, methanol, a) -78 deg C, 4 h, b) from -78 deg C to RT, 8 h 2: 99 percent / p-toluenesulfonic acid / 2 h / Ambient temperature 3: 99 percent / tetrabutylammonium fluoride / tetrahydrofuran / 3 h / Ambient temperature 4: 85 percent / sodium metaperiodate, water / diethyl ether / 3 h / Ambient temperature 5: 1.) lithium 2,2,6,6-tetramethylpiperidine / 1.) THF, RT, 30 min, 2.) THF, 3 h View Scheme