1: 86 percent / pyridine / 20 °C 2: 76 percent / H2SO4 / acetic acid / 4 °C 3: 89 percent / BSA; TMSOTf / acetonitrile / 60 - 65 °C 4: 91 percent / aq. NH3 / methanol; tetrahydrofuran / 60 °C 5: 95 percent / H2 / 10 percent Pd/C / methanol / 1 h / 20 °C View Scheme

1: 97 percent / H2 / 10 percent Pd/C / methanol / 2 h / 20 °C 2: 98 percent / pyridine / 20 °C 3: 77 percent / H2SO4 / acetic acid / 4 °C View Scheme

1: 86 percent / pyridine / 20 °C 2: 76 percent / H2SO4 / acetic acid / 4 °C 3: 88 percent / BSA; TMSOTf / acetonitrile / 60 - 65 °C 4: 93 percent / aq. NH3 / methanol; tetrahydrofuran / 60 °C 5: 98 percent / H2 / 10 percent Pd/C / methanol / 1 h / 20 °C View Scheme

1: 86 percent / pyridine / 20 °C 2: 76 percent / H2SO4 / acetic acid / 4 °C 3: 89 percent / BSA; TMSOTf / acetonitrile / 60 - 65 °C 4: 91 percent / aq. NH3 / methanol; tetrahydrofuran / 60 °C 5: 95 percent / H2 / 10 percent Pd/C / methanol / 1 h / 20 °C View Scheme