1.1: 2,6-di-tert-butyl-4-methylpyridine / dichloromethane / 0.33 h / 20 °C / Inert atmosphere; Molecular sieve 1.2: 1 h / 0 - 20 °C / Inert atmosphere; Molecular sieve 2.1: pyridine / 20 °C 3.1: methanol; dichloromethane / 0.5 h 3.2: Dowex H+ View Scheme