1: 69 percent / dimethylformamide / 24 h / Ambient temperature 2: 95 percent / DBU / dimethylformamide / 1 h / 100 °C 3: 82 percent / pyridine, water / 3.5 h / Heating 5: 48 percent / LiCl / dimethylformamide / 6 h / Ambient temperature 6: 60 percent / water / 24 h / Ambient temperature; Dowex-50(H+) 7: n-Bu3SnH, 2,2'-azobis(2-methylpropionitrile) / toluene / 1 h / Heating View Scheme