1.1: 87 percent / Dowex 50H+ / methanol / 48 h / 60 °C 2.1: 89 percent / DMAP; pyridine / 50 °C 3.1: 95 percent / AcOH; H2SO4 / 0.5 h / 20 °C 4.1: hexamethyldisilazane; ammonium sulfate / 16 h / Heating 4.2: 38 percent / stannic chloride / acetonitrile; CH2Cl2 / 18 h / 20 °C 5.1: 80 percent / NH3 / methanol / 24 h / 20 °C View Scheme

1: 87 percent / Dowex 50H+ / methanol / 48 h / 60 °C 2: 89 percent / DMAP; pyridine / 50 °C 3: 95 percent / AcOH; H2SO4 / 0.5 h / 20 °C 4: 69 percent / stannic chloride / CH2Cl2 / 3 h / Heating 5: 71 percent / triethylamine / methanol / 2 h / 20 °C 6: 74 percent / bromotrichloromethane; 1,8-diazabicyclo[5.4.0]-undec-7-ene / CH2Cl2 / 16 h / 0 °C 7: 85 percent / NH3 / methanol / 24 h / 20 °C View Scheme

1: 87 percent / Dowex 50H+ / methanol / 48 h / 60 °C 2: 89 percent / DMAP; pyridine / 50 °C 3: 95 percent / AcOH; H2SO4 / 0.5 h / 20 °C View Scheme

1: 87 percent / Dowex 50H+ / methanol / 48 h / 60 °C 2: 89 percent / DMAP; pyridine / 50 °C 3: 95 percent / AcOH; H2SO4 / 0.5 h / 20 °C 4: 69 percent / stannic chloride / CH2Cl2 / 3 h / Heating View Scheme

1: 87 percent / Dowex 50H+ / methanol / 48 h / 60 °C 2: 89 percent / DMAP; pyridine / 50 °C 3: 95 percent / AcOH; H2SO4 / 0.5 h / 20 °C 4: 69 percent / stannic chloride / CH2Cl2 / 3 h / Heating 5: 71 percent / triethylamine / methanol / 2 h / 20 °C 6: 74 percent / bromotrichloromethane; 1,8-diazabicyclo[5.4.0]-undec-7-ene / CH2Cl2 / 16 h / 0 °C View Scheme