sodium tetrahydroborate; nickel dichloride in methanol 0.0833333 h; Ambient temperature;

1: 75 percent / NiCl2*6H2O, NaBH4 / methanol / 0.08 h / Ambient temperature 2: 63 percent / CaCO3 / CH2Cl2; H2O / Ambient temperature 3: 97 percent / methanol / Ambient temperature 4: 81 percent / 15-crown-5-ether / acetonitrile / 1.17 h / Ambient temperature View Scheme

1: 75 percent / NiCl2*6H2O, NaBH4 / methanol / 0.08 h / Ambient temperature 2: 63 percent / CaCO3 / CH2Cl2; H2O / Ambient temperature 3: 97 percent / methanol / Ambient temperature 4: 92 percent / 15-crown-5-ether, piperidine / acetonitrile / 1.42 h / Ambient temperature View Scheme