sodium tetrahydroborate in methanol 1.) room temp., 16 h, reflux 1 h;

1: 29.3 percent / NaBH4 / methanol / 1.) room temp., 16 h, reflux 1 h 2: 8 percent / HgO, Na2EDTA / dimethylsulfoxide; H2O / 1 h / 100 °C View Scheme