1: 42 percent / pyridine / a) r.t., 0.5h, b) 80 deg C, 3h 2: DIBAL / tetrahydrofuran; hexane / 0.5 h / -75 °C 3: 0.2 percent HCl / 0.25 h / Ambient temperature 4: trimethylsilyl triflate / CH2Cl2 / Ambient temperature View Scheme

1: 42 percent / pyridine / a) r.t., 0.5h, b) 80 deg C, 3h 2: DIBAL / tetrahydrofuran; hexane / 0.5 h / -75 °C 3: 0.2 percent HCl / 0.25 h / Ambient temperature 4: trimethylsilyl triflate / CH2Cl2 / Ambient temperature View Scheme

trimethylsilyl trifluoromethanesulfonate in dichloromethane Ambient temperature;

ammonium hydroxide in methanol Ambient temperature;

1: 89 percent / POCl3, Et3N / acetonitrile / Ambient temperature 2: 20percent aq.NH3 / dioxane / Ambient temperature 3: 21 percent / methanolic ammonia / Ambient temperature View Scheme