1: HCl aq. / methanol / 2 h / Heating 2: 75 percent / pyridine; tetrahydrofuran / 2 h / Ambient temperature 3: 100 percent / pyridine / 40 h / 20 °C 4: 80 percent / Boric acid / Silicic acid column / diethyl ether; petroleum ether 5: tetrahydrofuran / 0.5 h / 20 °C 6: 1-Methylimidazole / acetonitrile; tetrahydrofuran / 0.75 h 7: N,N,N',N'-tetramethylguanidinium syn-4-nitrobenzaldoximate / tetrahydrofuran / 2 h / 20 °C View Scheme

1: HCl / methanol; CHCl3 / 1 h / Ambient temperature 2: 72 percent / Et3N / toluene / 60 h / 65 °C 3: 84 percent / 4-(dimethylamino)pyridine / CHCl3 / 36 h / Ambient temperature 4: HCl / methanol; CHCl3 / 1 h / Ambient temperature 5: 85 percent / acetonitrile / 6 h / Ambient temperature View Scheme

1: aq. HCl / diethyl ether 2: Py 3: dimethylsulfoxide View Scheme

1: 97 percent / aq.HCl / 1,2-dimethoxy-ethane / 1.5 h / Heating 2: 85.36 g / Et3N / tetrahydrofuran; acetonitrile / 15 h / Heating 3: 94.07 g / Et3N / CH2Cl2 / 1.5 h / -5 °C 4: dimethylformamide / 20 h / 90 °C 5: 95 percent / NaOMe / methanol; tetrahydrofuran / 0.5 h / 0 °C 6: 85 percent / BF3*Et2O / CH2Cl2 / 0.75 h / -10 °C 7: Et3N / benzene / 3.5 h / Ambient temperature 8: acetonitrile / 16 h / 50 °C 9: 1.) AgNO3, pyridine, 2.) pyridine, H2S / 1.) MeOH, CH3CN, 0 deg C, 30 min, 2.) CH2Cl2, 0 deg C, 30 min; room temperature, 1 h 10: 15.8 g / DMAP, DCC / CH2Cl2 / 3 h / Ambient temperature View Scheme

1: HCl aq. / methanol / 2 h / Heating 2: 75 percent / pyridine; tetrahydrofuran / 2 h / Ambient temperature 3: 100 percent / pyridine / 40 h / 20 °C 4: 80 percent / Boric acid / Silicic acid column / diethyl ether; petroleum ether View Scheme

1: HCl / methanol; CHCl3 / 1 h / Ambient temperature 2: 72 percent / Et3N / toluene / 60 h / 65 °C 3: 84 percent / 4-(dimethylamino)pyridine / CHCl3 / 36 h / Ambient temperature 4: HCl / methanol; CHCl3 / 1 h / Ambient temperature 5: 85 percent / acetonitrile / 6 h / Ambient temperature 6: 1.) Et3N, 2.) 0.1 M aq. KCl / 1.) CHCl3, r.t., 6 h; 40 deg C, 12 h, 2.) r.t., 1 h 7: 47 percent / CHCl3 / 14 h / 65 °C View Scheme

hydrogenchloride in methanol 2 h; Heating; Yield given;