1: 4-(N,N-dimethlyamino)pyridine; N-ethyl-N,N-diisopropylamine / dichloromethane / 0 - 40 °C 2: triethylsilane; titanium tetrachloride / dichloromethane / -78 - -10 °C 3: hydrogen azide; triphenylphosphine; diethylazodicarboxylate / tetrahydrofuran; benzene / 10 - 20 °C 4: 2,6-dimethylpyridine / chloroform / 6 h / 20 - 55 °C 5: zirconium tetrachloride; isopropyl alcohol / 4 h / 50 °C 6: hydrogen azide; triphenylphosphine; diethylazodicarboxylate / tetrahydrofuran; benzene / 10 - 20 °C View Scheme

1: hydrogen azide; triphenylphosphine; diethylazodicarboxylate / tetrahydrofuran; benzene / 10 - 20 °C 2: 2,6-dimethylpyridine / chloroform / 6 h / 20 - 55 °C 3: zirconium tetrachloride; isopropyl alcohol / 4 h / 50 °C 4: hydrogen azide; triphenylphosphine; diethylazodicarboxylate / tetrahydrofuran; benzene / 10 - 20 °C View Scheme

1: 2,6-dimethylpyridine / chloroform / 6 h / 20 - 55 °C 2: zirconium tetrachloride; isopropyl alcohol / 4 h / 50 °C 3: hydrogen azide; triphenylphosphine; diethylazodicarboxylate / tetrahydrofuran; benzene / 10 - 20 °C View Scheme

1: triethylsilane; titanium tetrachloride / dichloromethane / -78 - -10 °C 2: hydrogen azide; triphenylphosphine; diethylazodicarboxylate / tetrahydrofuran; benzene / 10 - 20 °C 3: 2,6-dimethylpyridine / chloroform / 6 h / 20 - 55 °C 4: zirconium tetrachloride; isopropyl alcohol / 4 h / 50 °C 5: hydrogen azide; triphenylphosphine; diethylazodicarboxylate / tetrahydrofuran; benzene / 10 - 20 °C View Scheme

1: orthoformic acid triethyl ester 2: 4-(N,N-dimethlyamino)pyridine; N-ethyl-N,N-diisopropylamine / dichloromethane / 0 - 40 °C 3: triethylsilane; titanium tetrachloride / dichloromethane / -78 - -10 °C 4: hydrogen azide; triphenylphosphine; diethylazodicarboxylate / tetrahydrofuran; benzene / 10 - 20 °C 5: 2,6-dimethylpyridine / chloroform / 6 h / 20 - 55 °C 6: zirconium tetrachloride; isopropyl alcohol / 4 h / 50 °C 7: hydrogen azide; triphenylphosphine; diethylazodicarboxylate / tetrahydrofuran; benzene / 10 - 20 °C View Scheme

1: BF3*Et2O / 2 h / 70 - 75 °C 2: pyridine, (dimethylamino)pyridine / 18 h / Ambient temperature View Scheme

1.1: 4-(N,N-dimethlyamino)pyridine; triethylamine / ethyl acetate / 1 h / 0 °C 2.1: sodium azide; ammonium chloride / water; N,N-dimethyl-formamide / 9 h / 20 °C 3.1: triphenylphosphine / ethanol / 0.33 h / 0 °C 3.2: 3 h / 0 - 20 °C 3.3: 3 h / Reflux 4.1: triethylamine / dichloromethane; water / 0.5 h / 0 °C 5.1: boron trifluoride diethyl etherate / 1.5 h / -8 °C 6.1: 4-(N,N-dimethlyamino)pyridine; triethylamine / ethyl acetate / 1 h / 0 °C 7.1: sodium hydride / tetrahydrofuran / 1 h / 20 °C 8.1: sodium azide; lithium chloride / N,N-dimethyl-formamide / 3 h / 80 °C View Scheme

1.1: sodium azide; ammonium chloride / water; N,N-dimethyl-formamide / 9 h / 20 °C 2.1: triphenylphosphine / ethanol / 0.33 h / 0 °C 2.2: 3 h / 0 - 20 °C 2.3: 3 h / Reflux 3.1: triethylamine / dichloromethane; water / 0.5 h / 0 °C 4.1: boron trifluoride diethyl etherate / 1.5 h / -8 °C 5.1: 4-(N,N-dimethlyamino)pyridine; triethylamine / ethyl acetate / 1 h / 0 °C 6.1: sodium hydride / tetrahydrofuran / 1 h / 20 °C 7.1: sodium azide; lithium chloride / N,N-dimethyl-formamide / 3 h / 80 °C View Scheme

1.1: triphenylphosphine / ethanol / 0.33 h / 0 °C 1.2: 3 h / 0 - 20 °C 1.3: 3 h / Reflux 2.1: triethylamine / dichloromethane; water / 0.5 h / 0 °C 3.1: boron trifluoride diethyl etherate / 1.5 h / -8 °C 4.1: 4-(N,N-dimethlyamino)pyridine; triethylamine / ethyl acetate / 1 h / 0 °C 5.1: sodium hydride / tetrahydrofuran / 1 h / 20 °C 6.1: sodium azide; lithium chloride / N,N-dimethyl-formamide / 3 h / 80 °C View Scheme

1: N-ethyl-N,N-diisopropylamine / dichloromethane / 0 °C 2: tetrabutyl ammonium fluoride / 2 h / 0 °C 3: 1-hydroxy-3H-benz[d][1,2]iodoxole-1,3-dione / dimethyl sulfoxide / 1 h / 25 °C 4: potassium carbonate / methanol / 2 h / 25 °C 5: pyridine; oct-1-ene; hydrogen / ethyl acetate / 6 h / 20 °C 6: Grubb's 2nd generation catalyst / dichloromethane / 14 h / |Reflux 7: ammonium chloride; sodium azide; water / ethanol; N,N-dimethyl-formamide / 10 h / 0 - 25 °C 8: triphenylphosphine / toluene / 3 h / 110 °C 9: 4-(N,N-dimethlyamino)pyridine; triethylamine / dichloromethane / 0.75 h / 0 - 25 °C 10: boron trifluoride diethyl etherate / 0.5 h / -10 °C 11: hydrogenchloride / ethanol; water / 12 h / 25 °C 12: triethylamine / dichloromethane / 1 h / 0 °C 13: sodium azide / N,N-dimethyl-formamide / 3 h / 80 °C View Scheme