aluminium trichloride in carbon disulfide 1.) 5 h, room temperature, 2.) 30 min., 40-50 deg C;

1: 56.7 percent / Na2S / tetrahydrofuran; ethanol / Heating 2: 60.6 percent / sodium methoxide / dioxane; methanol / 1.) 12 h, room temperature, 2.) 30 min., heating other solvent: EtOH 3: 91 percent / ethylene glycol, hyrazine hydrate / dioxane / 0.5 h / Heating 4: 90.2 percent / Raney nickel W-2 / dioxane / 1 h / Heating View Scheme