1: NaHCO3 / H2O; diethyl ether / 4 h / Ambient temperature 2: pyridine / 16 h / 8 - 10 °C 3: aq. TFA / 4 h / Ambient temperature 4: pyridine / Ambient temperature 5: 1.) hexamethyldisilazane, ammonium sulfate, 2.) trimethylsilyl triflate / 1.) reflux, 2.) MeCN, reflux, 5 h 6: 65 percent / Cs2CO3 / acetonitrile / 3 h / Ambient temperature 7: 66 percent / NH3 / methanol / Ambient temperature 8: 74 percent / 4-(dimethylamino)pyridine / acetonitrile / 24 h / Ambient temperature View Scheme

1: NaHCO3 / H2O; diethyl ether / 4 h / Ambient temperature 2: pyridine / 16 h / 8 - 10 °C 3: aq. TFA / 4 h / Ambient temperature 4: pyridine / Ambient temperature 5: 1.) hexamethyldisilazane, ammonium sulfate, 2.) trimethylsilyl triflate / 1.) reflux, 2.) MeCN, reflux, 5 h 6: Cs2CO3 / acetonitrile / 6 h / Ambient temperature 7: NH3 / methanol / Ambient temperature 8: 4-(dimethylamino)pyridine / acetonitrile / 48 h / Ambient temperature 9: 1.) 1,2,4-triazole, POCl3, pyridine, 2.) aq. NH3 / 1.) RT, 4 h, 2.) RT, 30 min View Scheme

1: NaHCO3 / H2O; diethyl ether / 4 h / Ambient temperature 2: pyridine / 16 h / 8 - 10 °C 3: aq. TFA / 4 h / Ambient temperature 4: pyridine / Ambient temperature 5: 1.) hexamethyldisilazane, ammonium sulfate, 2.) trimethylsilyl triflate / 1.) reflux, 2.) MeCN, reflux, 5 h 6: 65 percent / Cs2CO3 / acetonitrile / 3 h / Ambient temperature 7: 66 percent / NH3 / methanol / Ambient temperature 8: 74 percent / 4-(dimethylamino)pyridine / acetonitrile / 24 h / Ambient temperature 9: 70 percent / K2CO3 / acetone / 2.5 h / Heating View Scheme

1: NaHCO3 / H2O; diethyl ether / 4 h / Ambient temperature 2: pyridine / 16 h / 8 - 10 °C 3: aq. TFA / 4 h / Ambient temperature 4: pyridine / Ambient temperature 5: 1.) hexamethyldisilazane, ammonium sulfate, 2.) trimethylsilyl triflate / 1.) reflux, 2.) MeCN, reflux, 5 h 6: Cs2CO3 / acetonitrile / 4 h / Ambient temperature 7: NH3 / methanol / Ambient temperature 8: 4-(dimethylamino)pyridine / acetonitrile / 24 h / Ambient temperature View Scheme

1: NaHCO3 / H2O; diethyl ether / 4 h / Ambient temperature 2: pyridine / 16 h / 8 - 10 °C 3: aq. TFA / 4 h / Ambient temperature 4: pyridine / Ambient temperature 5: 1.) hexamethyldisilazane, ammonium sulfate, 2.) trimethylsilyl triflate / 1.) reflux, 2.) MeCN, reflux, 5 h 6: 65 percent / Cs2CO3 / acetonitrile / 3 h / Ambient temperature 7: 66 percent / NH3 / methanol / Ambient temperature 8: 74 percent / 4-(dimethylamino)pyridine / acetonitrile / 24 h / Ambient temperature 9: 1.) 1,2,4-triazole, POCl3, pyridine, 2.) aq. NH3 / 1.) RT, 4 h, 2.) RT, 30 min View Scheme

1: NaHCO3 / H2O; diethyl ether / 4 h / Ambient temperature 2: pyridine / 16 h / 8 - 10 °C 3: aq. TFA / 4 h / Ambient temperature 4: pyridine / Ambient temperature 5: 1.) hexamethyldisilazane, ammonium sulfate, 2.) trimethylsilyl triflate / 1.) reflux, 2.) MeCN, reflux, 5 h 6: Cs2CO3 / acetonitrile / 6 h / Ambient temperature 7: NH3 / methanol / Ambient temperature View Scheme

1: NaHCO3 / H2O; diethyl ether / 4 h / Ambient temperature 2: pyridine / 16 h / 8 - 10 °C 3: aq. TFA / 4 h / Ambient temperature 4: pyridine / Ambient temperature 5: 1.) hexamethyldisilazane, ammonium sulfate, 2.) trimethylsilyl triflate / 1.) reflux, 2.) MeCN, reflux, 5 h 6: Cs2CO3 / acetonitrile / 6 h / Ambient temperature 7: NH3 / methanol / Ambient temperature 8: 4-(dimethylamino)pyridine / acetonitrile / 48 h / Ambient temperature 9: 89 percent / K2CO3 / acetone / 6 h / Heating View Scheme

1: NaHCO3 / H2O; diethyl ether / 4 h / Ambient temperature 2: pyridine / 16 h / 8 - 10 °C 3: aq. TFA / 4 h / Ambient temperature 4: pyridine / Ambient temperature 5: 1.) hexamethyldisilazane, ammonium sulfate, 2.) trimethylsilyl triflate / 1.) reflux, 2.) MeCN, reflux, 5 h 6: 65 percent / Cs2CO3 / acetonitrile / 3 h / Ambient temperature View Scheme

hydroxylamine hydrochloride in pyridine; ethanol 1 h; Heating;

1: sodium tetrahydroborate / methanol / 3 h / 20 °C 2: sodium hydride / N,N-dimethyl-formamide / 0 °C View Scheme