tetramethylammonium borohydride in methanol T=0°C;

1: 16 percent / 50percent suspension of sodium hydride in oil / 1,2-dimethoxy-ethane 2: 67 percent / boron trifluoride etherate - mercuric oxide complex / 0 deg C, 30 min; then room temperature, 15 min 3: 84.5 percent / p-toluenesulfonic acid / acetone / 0.5 h / 80 - 90 °C 4: 96 percent / tetramethylammonium borohydride / methanol / 0 °C View Scheme

1: 16 percent / 50percent suspension of sodium hydride in oil / 1,2-dimethoxy-ethane 2: 67 percent / boron trifluoride etherate - mercuric oxide complex / 0 deg C, 30 min; then room temperature, 15 min 3: 84.5 percent / p-toluenesulfonic acid / acetone / 0.5 h / 80 - 90 °C 4: 96 percent / tetramethylammonium borohydride / methanol / 0 °C View Scheme

1: 67 percent / boron trifluoride etherate - mercuric oxide complex / 0 deg C, 30 min; then room temperature, 15 min 2: 84.5 percent / p-toluenesulfonic acid / acetone / 0.5 h / 80 - 90 °C 3: 96 percent / tetramethylammonium borohydride / methanol / 0 °C View Scheme

1: 84.5 percent / p-toluenesulfonic acid / acetone / 0.5 h / 80 - 90 °C 2: 96 percent / tetramethylammonium borohydride / methanol / 0 °C View Scheme