1: 1.) dibutyltin oxide, 2.) triethylamine / 1.) methanol, 5 h, reflux, 2.) methanol, 1 h, room temperature 2: 88 percent / 40 percent sodium hydrogensulfide aq. / dimethylformamide / 6 h / 60 °C 3: 18 percent / Raney nickel / H2O / 3 h / Heating View Scheme