1.1: N-iodo-succinimide / dichloromethane / 0.33 h / 20 °C / Inert atmosphere; Molecular sieve 1.2: 1 h / -30 °C / Inert atmosphere; Molecular sieve 2.1: sodium methylate / methanol / 0.33 h / 20 °C 2.2: Dowex H+ 3.1: hydrazine / ethanol / 70 °C 4.1: 4-(N,N-dimethlyamino)pyridine / pyridine / 2 h / 20 °C 5.1: pyridine / 20 °C 6.1: sodium methylate / methanol / 0.5 h 6.2: 1 h 6.3: Dowex H+ View Scheme

1.1: sodium methylate / methanol / 0.33 h / 20 °C 1.2: Dowex H+ 2.1: hydrazine / ethanol / 70 °C 3.1: 4-(N,N-dimethlyamino)pyridine / pyridine / 2 h / 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