1: 97 percent / pyridine / 1.) 0 deg C, 3 h, 2.) RT, 1 h 2: 89 percent / 50percent aq. HOAc / 0.42 h / Heating 3: 69 percent / dimethylformamide / 24 h / Ambient temperature 4: 95 percent / DBU / dimethylformamide / 1 h / 100 °C 5: 82 percent / pyridine, water / 3.5 h / Heating 7: 48 percent / LiCl / dimethylformamide / 6 h / Ambient temperature 8: 60 percent / water / 24 h / Ambient temperature; Dowex-50(H+) 9: n-Bu3SnH, 2,2'-azobis(2-methylpropionitrile) / toluene / 1 h / Heating View Scheme