1: 59 percent / aq acetic acid (80percent) / 20 h / 60 °C 2: 55.7 percent / imidazole / CHCl3 / 40 h / Heating 3: 74.2 percent / silver trifluoromethanesulphonate, 1,1,3,3-tetramethylurea / CH2Cl2 / 4.5 h / Ambient temperature 4: 1) sodium, 2) ammonium chloride / 1) liq NH3, THF, -70 deg C, 4 h 20 min, 2) room temp., 4.5 h View Scheme