1: With sodium methylate in methanol T=20°C; pH=10; 0.5 h; 2: in methanol

1.1: trimethylsilyl trifluoromethanesulfonate / dichloromethane / -20 °C 2.1: sodium methylate / methanol / 0.5 h / 20 °C / pH 10 2.2: Dowex H+ View Scheme

1.1: trimethylsilyl trifluoromethanesulfonate / dichloromethane / -20 °C 2.1: sodium methylate / methanol / 0.5 h / 20 °C / pH 10 2.2: Dowex H+ View Scheme

1.1: toluene-4-sulfonic acid / N,N-dimethyl-formamide; acetonitrile / 1 h / 20 °C 2.1: pyridine / 1 h / 0 °C / Cooling with ice 3.1: water; acetic acid / dichloromethane / 50 h / 20 - 50 °C 4.1: 2,6-di-tert-butyl-4-methylpyridine / dichloromethane / 0.33 h / 20 °C / Inert atmosphere; Molecular sieve 4.2: 1 h / 0 - 20 °C / Inert atmosphere; Molecular sieve 5.1: pyridine / 20 °C 6.1: methanol; dichloromethane / 0.5 h 6.2: Dowex H+ View Scheme

1.1: toluene-4-sulfonic acid / N,N-dimethyl-formamide; acetonitrile / 1 h / 20 °C 2.1: dichloromethane / 0.33 h / Inert atmosphere; Molecular sieve 2.2: 2 h / -20 °C / Inert atmosphere; Molecular sieve 3.1: water; acetic acid / dichloromethane / 20 °C 4.1: pyridine / 20 °C 5.1: sodium methylate / methanol / 0.5 h 5.2: 1 h 5.3: Dowex H+ View Scheme

1.1: toluene-4-sulfonic acid / N,N-dimethyl-formamide; acetonitrile / 1 h / 20 °C 2.1: N-iodo-succinimide / dichloromethane / 0.33 h / 20 °C / Inert atmosphere; Molecular sieve 2.2: 1 h / -30 °C / Inert atmosphere; Molecular sieve 3.1: water; acetic acid / dichloromethane / 48 h / 20 °C 4.1: N-iodo-succinimide / dichloromethane / 0.33 h / 20 °C / Inert atmosphere; Molecular sieve 4.2: 1 h / -30 °C / Inert atmosphere; Molecular sieve 5.1: sodium methylate / methanol / 0.33 h / 20 °C 5.2: Dowex H+ 6.1: hydrazine / ethanol / 70 °C 7.1: 4-(N,N-dimethlyamino)pyridine / pyridine / 2 h / 20 °C 8.1: pyridine / 20 °C 9.1: sodium methylate / methanol / 0.5 h 9.2: 1 h 9.3: Dowex H+ View Scheme

1.1: toluene-4-sulfonic acid / N,N-dimethyl-formamide; acetonitrile / 1 h / 20 °C 2.1: N-iodo-succinimide / dichloromethane / 0.33 h / 20 °C / Inert atmosphere; Molecular sieve 2.2: 1 h / -30 °C / Inert atmosphere; Molecular sieve 3.1: water; acetic acid / dichloromethane / 48 h / 20 °C 4.1: sodium methylate / methanol / 0.33 h / 20 °C 4.2: Dowex H+ 5.1: hydrazine / ethanol / 70 °C 6.1: 4-(N,N-dimethlyamino)pyridine / pyridine / 2 h / 20 °C 7.1: pyridine / 20 °C 8.1: sodium methylate / methanol / 0.5 h 8.2: 1 h 8.3: Dowex H+ View Scheme

1: With sodium methylate in methanol T=20°C; pH=10; 0.5 h; 2: in methanol

1.1: trimethylsilyl trifluoromethanesulfonate / dichloromethane / -20 °C 2.1: sodium methylate / methanol / 0.5 h / 20 °C / pH 10 2.2: Dowex H+ View Scheme

1.1: trimethylsilyl trifluoromethanesulfonate / dichloromethane / -20 °C 2.1: sodium methylate / methanol / 0.5 h / 20 °C / pH 10 2.2: Dowex H+ View Scheme